systemd
Daemonjournalctl
: Query the systemd
Journaludev
systemd
Daemonjournalctl
: Query the systemd
Journaludev
/dev
Directoryuevents
and udev
udev
Daemonudev
Rulesudev
cachemgr.cgi
)wicked
architecturesystemd
Target Unitsulimit
: Setting Resources for the Userrpm -q -i wget
/var/run/netconfig/resolv.conf
/etc/hosts
/etc/networks
/etc/host.conf
/etc/nsswitch.conf
ulimit
: Settings in ~/.bashrc
udev
Rulesrpcclient
to Request a Windows Server 2012 Share SnapshotVirtualHost
EntriesVirtualHost
DirectivesVirtualHost
DirectivesVirtualHost
Configurationsquidclient
Copyright © 2006– 2020 SUSE LLC and contributors. All rights reserved.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or (at your option) version 1.3; with the Invariant Section being this copyright notice and license. A copy of the license version 1.2 is included in the section entitled “GNU Free Documentation License”.
For SUSE trademarks, see https://www.suse.com/company/legal/. All other third-party trademarks are the property of their respective owners. Trademark symbols (®, ™ etc.) denote trademarks of SUSE and its affiliates. Asterisks (*) denote third-party trademarks.
All information found in this book has been compiled with utmost attention to detail. However, this does not guarantee complete accuracy. Neither SUSE LLC, its affiliates, the authors nor the translators shall be held liable for possible errors or the consequences thereof.
This manual gives you a general understanding of openSUSE® Leap. It is intended mainly for system administrators and home users with basic system administration knowledge. Check out the various parts of this manual for a selection of applications needed in everyday life and in-depth descriptions of advanced installation and configuration scenarios.
Learn about advanced adminstrations tasks such as using YaST in text mode and managing software from the command line. Find out how to do system rollbacks with Snapper and how to use advanced storage techniques on openSUSE Leap.
Get an introduction to the components of your Linux system and a deeper understanding of their interaction.
Learn how to configure the various network and file services that come with openSUSE Leap.
Get an introduction to mobile computing with openSUSE Leap, get to know the various options for wireless computing and power management.
Documentation for our products is available at http://doc.opensuse.org/, where you can also find the latest updates, and browse or download the documentation in various formats. The latest documentation updates are usually available in the English version of the documentation.
The following documentation is available for this product:
This manual will see you through your initial contact with openSUSE® Leap. Check out the various parts of this manual to learn how to install, use and enjoy your system.
Covers system administration tasks like maintaining, monitoring and customizing an initially installed system.
Describes virtualization technology in general, and introduces libvirt—the unified interface to virtualization—and detailed information on specific hypervisors.
AutoYaST is a system for unattended mass deployment of openSUSE Leap systems using an AutoYaST profile containing installation and configuration data. The manual guides you through the basic steps of auto-installation: preparation, installation, and configuration.
Introduces basic concepts of system security, covering both local and network security aspects. Shows how to use the product inherent security software like AppArmor, SELinux, or the auditing system that reliably collects information about any security-relevant events. Supports the administrator with security-related choices and decisions in installing and setting up a secure SUSE Linux Enterprise Server and additional processes to further secure and harden that installation.
An administrator's guide for problem detection, resolution and optimization. Find how to inspect and optimize your system by means of monitoring tools and how to efficiently manage resources. Also contains an overview of common problems and solutions and of additional help and documentation resources.
Introduces the GNOME desktop of openSUSE Leap. It guides you through using and configuring the desktop and helps you perform key tasks. It is intended mainly for end users who want to make efficient use of GNOME as their default desktop.
The release notes for this product are available at https://www.suse.com/releasenotes/.
Your feedback and contributions to this documentation are welcome! Several channels are available:
Report issues with the documentation at https://bugzilla.opensuse.org/. To simplify this process, you can use the links next to headlines in the HTML version of this document. These preselect the right product and category in Bugzilla and add a link to the current section. You can start typing your bug report right away. A Bugzilla account is required.
To contribute to this documentation, use the
links next to headlines in the HTML version of this document. They take you to the source code on GitHub, where you can open a pull request. A GitHub account is required.For more information about the documentation environment used for this documentation, see the repository's README.
Alternatively, you can report errors and send feedback concerning the documentation to <doc-team@suse.com>. Make sure to include the document title, the product version and the publication date of the documentation. Refer to the relevant section number and title (or include the URL) and provide a concise description of the problem.
If you need further help on openSUSE Leap, see https://en.opensuse.org/Portal:Support.
The following notices and typographical conventions are used in this documentation:
/etc/passwd
: directory names and file names
PLACEHOLDER: replace PLACEHOLDER with the actual value
PATH
: the environment variable PATH
ls
, --help
: commands, options, and
parameters
user
: users or groups
package name : name of a package
Alt, Alt–F1: a key to press or a key combination; keys are shown in uppercase as on a keyboard
, › : menu items, buttons
Dancing Penguins (Chapter Penguins, ↑Another Manual): This is a reference to a chapter in another manual.
Commands that must be run with root
privileges. Often you can also
prefix these commands with the sudo
command to run them
as non-privileged user.
root #
command
tux >
sudo
command
Commands that can be run by non-privileged users.
tux >
command
Notices
Vital information you must be aware of before proceeding. Warns you about security issues, potential loss of data, damage to hardware, or physical hazards.
Important information you should be aware of before proceeding.
Additional information, for example about differences in software versions.
Helpful information, like a guideline or a piece of practical advice.
The source code of openSUSE Leap is publicly available. Refer to http://en.opensuse.org/Source_code for download links and more information.
With a lot of voluntary commitment, the developers of Linux cooperate on a global scale to promote the development of Linux. We thank them for their efforts—this distribution would not exist without them. Special thanks, of course, goes to Linus Torvalds.
The ncurses-based pseudo-graphical YaST interface is designed primarily to help system administrators to manage systems without an X server. The interface offers several advantages compared to the conventional GUI. You can navigate the ncurses interface using the keyboard, and there are keyboard sho…
This chapter describes Zypper and RPM, two command line tools for managing
software. For a definition of the terminology used in this context (for
example, repository
, patch
, or
update
) refer to
Book “Start-Up”, Chapter 10 “Installing or Removing Software”, Section 10.1 “Definition of Terms”.
Snapper allows creating and managing file system snapshots. File system snapshots allow keeping a copy of the state of a file system at a certain point of time. The standard setup of Snapper is designed to allow rolling back system changes. However, you can also use it to create on-disk backups of user data. As the basis for this functionality, Snapper uses the Btrfs file system or thinly-provisioned LVM volumes with an XFS or Ext4 file system.
Virtual Network Computing (VNC) enables you to access a remote computer via a graphical desktop, and run remote graphical applications. VNC is platform-independent and accesses the remote machine from any operating system. This chapter describes how to connect to a VNC server with the desktop clients vncviewer and Remmina, and how to operate a VNC server.
openSUSE Leap supports two different kinds of VNC sessions: One-time sessions that “live” as long as the VNC connection from the client is kept up, and persistent sessions that “live” until they are explicitly terminated.
A VNC server can offer both kinds of sessions simultaneously on different ports, but an open session cannot be converted from one type to the other.
Sophisticated system configurations require specific disk setups. All common partitioning tasks can be done during the installation. To get persistent device naming with block devices, use the block devices below /dev/disk/by-id or /dev/disk/by-uuid. Logical Volume Management (LVM) is a disk partiti…
openSUSE Leap supports the parallel installation of multiple kernel versions. When installing a second kernel, a boot entry and an initrd are automatically created, so no further manual configuration is needed. When rebooting the machine, the newly added kernel is available as an additional boot parameter.
Using this functionality, you can safely test kernel updates while being able to always fall back to the proven former kernel. To do this, do not use the update tools (such as the YaST Online Update or the updater applet), but instead follow the process described in this chapter.
openSUSE Leap includes the X.org server, Wayland and the GNOME desktop. This chapter describes the configuration of the graphical user interface for all users.
The ncurses-based pseudo-graphical YaST interface is designed primarily to help system administrators to manage systems without an X server. The interface offers several advantages compared to the conventional GUI. You can navigate the ncurses interface using the keyboard, and there are keyboard shortcuts for practically all interface elements. The ncurses interface is light on resources, and runs fast even on modest hardware. You can run the ncurses-based version of YaST via an SSH connection, so you can administer remote systems. Keep in mind that the minimum supported size of the terminal emulator in which to run YaST is 80x25 characters.
To launch the ncurses-based version of YaST, open the terminal and run the
sudo yast2
command. Use the Tab or
arrow keys to navigate between interface elements like menu
items, fields, and buttons. All menu items and buttons in YaST can be
accessed using the appropriate function keys or keyboard shortcuts. For
example, you can cancel the current operation by pressing
F9, while the F10 key can be used to accept
the changes. Each menu item and button in YaST's ncurses-based interface
has a highlighted letter in its label. This letter is part of the keyboard
shortcut assigned to the interface element. For example, the letter
Q
is highlighted in the
button. This means that you can activate the button by pressing
Alt–Alt+Q.
If a YaST dialog gets corrupted or distorted (for example, while resizing the window), press Ctrl–L to refresh and restore its contents.
The ncurses-based version of YaST offers several advanced key combinations.
List advanced hotkeys.
Change color schema.
Quit the application.
Refresh screen.
List advanced hotkeys.
Dump dialog to the log file as a screenshot.
Open YDialogSpy to see the widget hierarchy.
If your window manager uses global Alt combinations, the Alt combinations in YaST might not work. Keys like Alt or Shift can also be occupied by the settings of the terminal.
Alt shortcuts can be executed with Esc instead of Alt. For example, Esc–H replaces Alt–H. (Press Esc, then press H.)
If the Alt and Shift combinations are taken over by the window manager or the terminal, use the combinations Ctrl–F (forward) and Ctrl–B (backward) instead.
The function keys (F1 ... F12) are also used for functions. Certain function keys might be taken over by the terminal and may not be available for YaST. However, the Alt key combinations and function keys should always be fully available on a text-only console.
Besides the text mode interface, YaST provides a command line interface. To get a list of YaST command line options, use the following command:
tux >
sudo
yast -h
If you know the package name, and the package is provided by an active
installation repository, you can use the command line option
-i
to install the package:
tux >
sudo
yast -i package_name
or
tux >
sudo
yast --install -i package_name
package_name can be a single short package name (for example gvim) installed with dependency checking, or the full path to an RPM package, which is installed without dependency checking.
While YaST offers basic functionality for managing software from the command line, consider using Zypper for more advanced package management tasks. Find more information on using Zypper in Section 2.1, “Using Zypper”.
To save time, you can start individual YaST modules using the following command:
tux >
sudo
yast module_name
View a list of all modules available on your system with yast
-l
or yast --list
.
To use YaST functionality in scripts, YaST provides command line support for individual modules. However, not all modules have command line support. To display the available options of a module, use the following command:
tux >
sudo
yast module_name help
If a module does not provide command line support, it is started in a text mode with the following message:
This YaST module does not support the command line interface.
The following sections describe all YaST modules with command line support, along with a brief explanation of all their commands and available options.
All YaST modules support the following commands:
Lists all the module's supported commands with their description:
tux >
sudo
yast lan help
Same as help
, but adds a detailed list of all
command's options and their descriptions:
tux >
sudo
yast lan longhelp
Same as longhelp
, but the output is structured as
an XML document and redirected to a file:
tux >
sudo
yast lan xmlhelp xmlfile=/tmp/yast_lan.xml
Enters the interactive mode. This lets you run the
module's commands without prefixing them with sudo
yast
. Use exit
to leave the interactive
mode.
Adds a new add-on product from the specified path:
tux >
sudo
yast add-on http://server.name/directory/Lang-AddOn-CD1/
You can use the following protocols to specify the source path: http:// ftp:// nfs:// disk:// cd:// or dvd://.
Displays and configures the Linux Audit Framework. Refer to the Book “Security and Hardening Guide” for more details. yast audit-laf
accepts the following commands:
Sets an option:
tux >
sudo
yast audit-laf set log_file=/tmp/audit.log
For a complete list of options, run yast audit-laf set help
.
Displays settings of an option:
tux >
sudo
yast audit-laf show diskspace space_left: 75 space_left_action: SYSLOG admin_space_left: 50 admin_space_left_action: SUSPEND action_mail_acct: root disk_full_action: SUSPEND disk_error_action: SUSPEND
For a complete list of options, run yast audit-laf show
help
.
Manages the DHCP server and configures its settings. yast
dhcp-server
accepts the following commands:
Disables the DHCP server service.
Enables the DHCP server service.
Configures settings for individual hosts.
Specifies to which network interface to listen to:
tux >
sudo
yast dhcp-server interface current Selected Interfaces: eth0 Other Interfaces: bond0, pbu, eth1
For a complete list of options, run yast dhcp-server interface
help
.
Manages global DHCP options. For a complete list of options, run
yast dhcp-server options help
.
Prints the status of the DHCP service.
Manages the DHCP subnet options. For a complete list of options, run
yast dhcp-server subnet help
.
Manages the DNS server configuration. yast dns-server
accepts the following commands:
Displays access control list settings:
tux >
sudo
yast dns-server acls show ACLs: ----- Name Type Value ---------------------------- any Predefined localips Predefined localnets Predefined none Predefined
Configures zone resource records:
tux >
sudo
yast dnsrecord add zone=example.org query=office.example.org type=NS value=ns3
For a complete list of options, run yast dns-server dnsrecord
help
.
Configures DNS forwarders:
tux >
sudo
yast dns-server forwarders add ip=10.0.0.100tux >
sudo
yast dns-server forwarders show [...] Forwarder IP ------------ 10.0.0.100
For a complete list of options, run yast dns-server forwarders
help
.
Handles 'A' and its related 'PTR' record at once:
tux >
sudo
yast dns-server host show zone=example.org
For a complete list of options, run yast dns-server host
help
.
Configures logging settings:
tux >
sudo
yast dns-server logging set updates=no transfers=yes
For a complete list of options, run yast dns-server logging
help
.
Configures zone mail servers:
tux >
sudo
yast dns-server mailserver add zone=example.org mx=mx1 priority=100
For a complete list of options, run yast dns-server mailserver
help
.
Configures zone name servers:
tux >
sudo
yast dns-server nameserver add zone=example.com ns=ns1
For a complete list of options, run yast dns-server nameserver
help
.
Configures the start of authority (SOA) record:
tux >
sudo
yast dns-server soa set zone=example.org serial=2006081623 ttl=2D3H20S
For a complete list of options, run yast dns-server soa help
.
Manages the DNS server service:
tux >
sudo
yast dns-server startup atboot
For a complete list of options, run yast dns-server startup help
.
Configures zone transport rules. For a complete list of options, run
yast dns-server transport help
.
Manages DNS zones:
tux >
sudo
yast dns-server zones add name=example.org zonetype=master
For a complete list of options, run yast dns-server zones help
.
Prints information about all disks or partitions. The only supported
command is list
followed by either of the following
options:
Lists all configured disks in the system:
tux >
sudo
yast disk list disks Device | Size | FS Type | Mount Point | Label | Model ---------+------------+---------+-------------+-------+------------- /dev/sda | 119.24 GiB | | | | SSD 840 /dev/sdb | 60.84 GiB | | | | WD1003FBYX-0
Lists all partitions in the system:
tux >
sudo
yast disk list partitions Device | Size | FS Type | Mount Point | Label | Model ---------------+------------+---------+-------------+-------+------ /dev/sda1 | 1.00 GiB | Ext2 | /boot | | /dev/sdb1 | 1.00 GiB | Swap | swap | | /dev/sdc1 | 698.64 GiB | XFS | /mnt/extra | | /dev/vg00/home | 580.50 GiB | Ext3 | /home | | /dev/vg00/root | 100.00 GiB | Ext3 | / | | [...]
Configures FTP server settings. yast ftp-server
accepts
the following options:
Controls secure connections via SSL and TLS. SSL
options are valid for the vsftpd
only.
tux >
sudo
yast ftp-server SSL enabletux >
sudo
yast ftp-server TLS disable
Configures access permissions:
tux >
sudo
yast ftp-server access authen_only
For a complete list of options, run yast ftp-server access
help
.
Configures access permissions for anonymous users:
tux >
sudo
yast ftp-server anon_access can_upload
For a complete list of options, run yast ftp-server
anon_access help
.
Specifies the directory for anonymous users. The directory must already exist on the server:
tux >
sudo
yast ftp-server anon_dir set_anon_dir=/srv/ftp
For a complete list of options, run yast ftp-server anon_dir
help
.
Controls change root environment (chroot):
tux >
sudo
yast ftp-server chroot enabletux >
sudo
yast ftp-server chroot disable
Sets the maximum idle time in minutes before FTP server terminates the current connection:
tux >
sudo
yast ftp-server idle-time set_idle_time=15
Determines whether to save the log messages into a log file:
tux >
sudo
yast ftp-server logging enabletux >
sudo
yast ftp-server logging disable
Specifies the maximum number of concurrently connected clients:
tux >
sudo
yast ftp-server max_clients set_max_clients=1500
Specifies the maximum number of concurrently connected clients via IP:
tux >
sudo
yast ftp-server max_clients_ip set_max_clients=20
Specifies the maximum data transfer rate permitted for anonymous clients (KB/s):
tux >
sudo
yast ftp-server max_rate_anon set_max_rate=10000
Specifies the maximum data transfer rate permitted for locally authenticated users (KB/s):
tux >
sudo
yast ftp-server max_rate_authen set_max_rate=10000
Specifies the port range for passive connection replies:
tux >
sudo
yast ftp-server port_range set_min_port=20000 set_max_port=30000
For a complete list of options, run yast ftp-server port_range help
.
Displays FTP server settings.
Controls the FTP start-up method:
tux >
sudo
yast ftp-server startup atboot
For a complete list of options, run yast ftp-server startup
help
.
Specifies the file umask for authenticated:anonymous
users:
tux >
sudo
yast ftp-server umask set_umask=177:077
Specifies the text to display when someone connects to the FTP server:
tux >
sudo
yast ftp-server welcome_message set_message="hello everybody"
Configures the HTTP server (Apache2). yast http-server
accepts the following commands:
Configures the HTTP server host settings:
tux >
sudo
yast http-server configure host=main servername=www.example.com \ serveradmin=admin@example.com
For a complete list of options, run yast http-server configure
help
.
Configures virtual hosts:
tux >
sudo
yast http-server hosts create servername=www.example.com \ serveradmin=admin@example.com documentroot=/var/www
For a complete list of options, run yast http-server hosts
help
.
Specifies the ports and network addresses where the HTTP server should listen:
tux >
sudo
yast http-server listen add=81tux >
sudo
yast http-server listen list Listen Statements: ================== :80 :81tux >
sudo
yast http-server delete=80
For a complete list of options, run yast http-server listen
help
.
Enables or disables the wizard mode:
tux >
sudo
yast http-server mode wizard=on
Controls the Apache2 server modules:
tux >
sudo
yast http-server modules enable=php5,rewritetux >
sudo
yast http-server modules disable=ssltux >
sudo
http-server modules list [...] Enabled rewrite Disabled ssl Enabled php5 [...]
Configures kdump
settings. For more information
on kdump
, refer to the
Book “System Analysis and Tuning Guide”, Chapter 17 “Kexec and Kdump”, Section 17.7 “Basic Kdump Configuration”. yast kdump
accepts the following commands:
Copies the kernel into the dump directory.
Specifies the kernel_string part of the name
of the custom kernel. The naming scheme is
/boot/vmlinu[zx]-kernel_string[.gz]
.
tux >
sudo
yast kdump customkernel kernel=kdump
For a complete list of options, run yast kdump customkernel
help
.
Specifies the (compression) format of the dump kernel image. Available formats are 'none', 'ELF', 'compressed', or 'lzo':
tux >
sudo
yast kdump dumpformat dump_format=ELF
Specifies the dump level number in the range from 0 to 31:
tux >
sudo
yast kdump dumplevel dump_level=24
Specifies the destination for saving dump images:
tux >
sudo
kdump dumptarget taget=ssh server=name_server port=22 \ dir=/var/log/dump user=user_name
For a complete list of options, run yast kdump dumptarget
help
.
Controls whether the system should reboot immediately after saving the core in the kdump kernel:
tux >
sudo
yast kdump immediatereboot enabletux >
sudo
yast kdump immediatereboot disable
Specifies how many old dump images are kept. Specify zero to keep them all:
tux >
sudo
yast kdump keepolddumps no=5
Specifies the command line that needs to be passed off to the kdump kernel:
tux >
sudo
yast kdump kernelcommandline command="ro root=LABEL=/"
Specifies the command line that you need to append to the default command line string:
tux >
sudo
yast kdump kernelcommandlineappend command="ro root=LABEL=/"
Specifies an e-mail address for sending copies of notification messages:
tux >
sudo
yast kdump notificationcc email="user1@example.com user2@example.com"
Specifies an e-mail address for sending notification messages:
tux >
sudo
yast kdump notificationto email="user1@example.com user2@example.com"
Displays kdump
settings:
tux >
sudo
yast kdump show Kdump is disabled Dump Level: 31 Dump Format: compressed Dump Target Settings target: file file directory: /var/crash Kdump immediate reboots: Enabled Numbers of old dumps: 5
Specifies the file with the plain text SMTP password used for sending notification messages:
tux >
sudo
yast kdump smtppass pass=/path/to/file
Specifies the SMTP server host name used for sending notification messages:
tux >
sudo
yast kdump smtpserver server=smtp.server.com
Specifies the SMTP user name used for sending notification messages:
tux >
sudo
yast kdump smtpuser user=smtp_user
Enables or disables start-up options:
tux >
sudo
yast kdump startup enable alloc_mem=128,256tux >
sudo
yast kdump startup disable
Configures the system keyboard for virtual consoles. It does not affect
the keyboard settings in graphical desktop environments, such as GNOME
or KDE. yast keyboard
accepts the following commands:
Lists all available keyboard layouts.
Activates new keyboard layout setting:
tux >
sudo
yast keyboard set layout=czech
Displays the current keyboard configuration.
Configures network cards. yast lan
accepts the
following commands:
Configures a new network card:
tux >
sudo
yast lan add name=vlan50 ethdevice=eth0 bootproto=dhcp
For a complete list of options, run yast lan add
help
.
Deletes an existing network card:
tux >
sudo
yast lan delete id=0
Changes the configuration of an existing network card:
tux >
sudo
yast lan edit id=0 bootproto=dhcp
Displays a summary of network card configuration:
tux >
sudo
yast lan list id name, bootproto 0 Ethernet Card 0, NONE 1 Network Bridge, DHCP
Configures system languages. yast language
accepts the
following commands:
Lists all available languages.
Specifies the main system languages and secondary languages:
tux >
sudo
yast language set lang=cs_CZ languages=en_US,es_ES no_packages
Displays the configuration of the mail system:
tux >
sudo
yast mail summary
Controls the NFS client. yast nfs
accepts the following
commands:
Adds a new NFS mount:
tux >
sudo
yast nfs add spec=remote_host:/path/to/nfs/share file=/local/mount/point
For a complete list of options, run yast nfs add help
.
Deletes an existing NFS mount:
tux >
sudo
yast nfs delete spec=remote_host:/path/to/nfs/share file=/local/mount/point
For a complete list of options, run yast nfs delete help
.
Changes an existing NFS mount:
tux >
sudo
yast nfs edit spec=remote_host:/path/to/nfs/share \ file=/local/mount/point type=nfs4
For a complete list of options, run yast nfs edit help
.
Lists existing NFS mounts:
tux >
sudo
yast nfs list Server Remote File System Mount Point Options ---------------------------------------------------------------- nfs.example.com /mnt /nfs/mnt nfs nfs.example.com /home/tux/nfs_share /nfs/tux nfs
Configures the NFS server. yast nfs-server
accepts the
following commands:
Adds a directory to export:
tux >
sudo
yast nfs-server add mountpoint=/nfs/export hosts=*.allowed_hosts.com
For a complete list of options, run yast nfs-server add help
.
Deletes a directory from the NFS export:
tux >
sudo
yast nfs-server delete mountpoint=/nfs/export
Specifies additional parameters for the NFS server:
tux >
sudo
yast nfs-server set enablev4=yes security=yes
For a complete list of options, run yast nfs-server set help
.
Starts the NFS server service:
tux >
sudo
yast nfs-server start
Stops the NFS server service:
tux >
sudo
yast nfs-server stop
Displays a summary of the NFS server configuration:
tux >
sudo
yast nfs-server summary NFS server is enabled NFS Exports * /mnt * /home NFSv4 support is enabled. The NFSv4 domain for idmapping is localdomain. NFS Security using GSS is enabled.
Configures the NIS client. yast nis
accepts the
following commands:
Changes global settings of a NIS client:
tux >
sudo
yast nis configure server=nis.example.com broadcast=yes
For a complete list of options, run yast nis configure
help
.
Disables the NIS client:
tux >
sudo
yast nis disable
Enables your machine as NIS client:
tux >
sudo
yast nis enable server=nis.example.com broadcast=yes automounter=yes
For a complete list of options, run yast nis enable help
.
Shows available NIS servers for a given domain:
tux >
sudo
yast nis find domain=nisdomain.com
Displays a configuration summary of a NIS client.
Configures a NIS server. yast nis-server
accepts the
following commands:
Configures a NIS master server:
tux >
sudo
yast nis-server master domain=nisdomain.com yppasswd=yes
For a complete list of options, run yast nis-server master help
.
Configures a NIS slave server:
tux >
sudo
yast nis-server slave domain=nisdomain.com master_ip=10.100.51.65
For a complete list of options, run yast nis-server slave help
.
Stops a NIS server:
tux >
sudo
yast nis-server stop
Displays a configuration summary of a NIS server:
tux >
sudo
yast nis-server summary
Configures proxy settings. yast proxy
accepts the
following commands:
Specifies the authentication options for proxy:
tux >
sudo
yast proxy authentication username=tux password=secret
For a complete list of options, run yast proxy authentication
help
.
Enables or disables proxy settings.
Changes the current proxy settings:
tux >
sudo
yast proxy set https=proxy.example.com
For a complete list of options, run yast proxy set help
.
Displays proxy settings.
Controls remote desktop settings. yast rdp
accepts the
following commands:
Allows remote access to the server's desktop:
tux >
sudo
yast rdp allow set=yes
Displays the remote desktop configuration summary.
Configures the Samba client settings. yast samba-client
accepts the following commands:
Changes global settings of Samba:
tux >
sudo
yast samba-client configure workgroup=FAMILY
Checks whether the machine is a member of a domain:
tux >
sudo
yast samba-client isdomainmember domain=SMB_DOMAIN
Makes the machine a member of a domain:
tux >
sudo
yast samba-client joindomain domain=SMB_DOMAIN user=username password=pwd
Enables or disables Winbind services (the
winbindd
daemon):
tux >
sudo
yast samba-client winbind enabletux >
sudo
yast samba-client winbind disable
Configures Samba server settings. yast samba-server
accepts the following commands:
Specifies the back-end for storing user information:
tux >
sudo
yast samba-server backend smbpasswd
For a complete list of options, run yast samba-server backend help
.
Configures global settings of the Samba server:
tux >
sudo
yast samba-server configure workgroup=FAMILY description='Home server'
For a complete list of options, run yast samba-server configure help
.
Displays a list of available shares:
tux >
sudo
yast samba-server list Status Type Name ============================== Disabled Disk profiles Enabled Disk print$ Enabled Disk homes Disabled Disk groups Enabled Disk movies Enabled Printer printers
Specifies the role of the Samba server:
tux >
sudo
yast samba-server role standalone
For a complete list of options, run yast samba-server role help
.
Enables or disables the Samba services (smb
and nmb
):
tux >
sudo
yast samba-server service enabletux >
sudo
yast samba-server service disable
Manipulates a single Samba share:
tux >
sudo
yast samba-server share name=movies browseable=yes guest_ok=yes
For a complete list of options, run yast samba-server share help
.
Controls the security level of the host. yast security
accepts the following commands:
Specifies the security level of the host:
tux >
sudo
yast security level server
For a complete list of options, run yast security level help
.
Sets the value of a specific option:
tux >
sudo
yast security set passwd=sha512 crack=yes
For a complete list of options, run yast security set help
.
Displays a summary of the current security configuration:
sudo
yast security summary
Configures sound card settings. yast sound
accepts the
following commands:
Configures a new sound card. Without any parameters, the command adds the first detected card.
tux >
sudo
yast sound add card=0 volume=75
For a complete list of options, run yast sound add
help
.
Lists available volume channels of a sound card:
tux >
sudo
yast sound channels card=0 Master 75 PCM 100
Lists all available sound kernel modules:
tux >
sudo
yast sound modules snd-atiixp ATI IXP AC97 controller (snd-atiixp) snd-atiixp-modem ATI IXP MC97 controller (snd-atiixp-modem) snd-virtuoso Asus Virtuoso driver (snd-virtuoso) [...]
Plays a test sound on a sound card:
tux >
sudo
yast sound playtest card=0
Removes a configured sound card:
tux >
sudo
yast sound remove card=0tux >
sudo
yast sound remove all
Specifies new values for a sound card:
tux >
sudo
yast sound set card=0 volume=80
Displays detailed information about a sound card:
tux >
sudo
yast sound show card=0 Parameters of card 'ThinkPad X240' (using module snd-hda-intel): align_buffer_size Force buffer and period sizes to be multiple of 128 bytes. bdl_pos_adj BDL position adjustment offset. beep_mode Select HDA Beep registration mode (0=off, 1=on) (default=1). Default Value: 0 enable_msi Enable Message Signaled Interrupt (MSI) [...]
Prints a configuration summary for all sound cards on the system:
tux >
sudo
yast sound summary
Specifies the volume level of a sound card:
sudo
yast sound volume card=0 play
Controls the variables in files under /etc/sysconfig
.
yast sysconfig
accepts the following commands:
Sets empty value to a variable:
tux >
sudo
yast sysconfig clear=POSTFIX_LISTEN
If the variable is available in several files, use the VARIABLE_NAME$FILE_NAME syntax:
tux >
sudo
yast sysconfig clear=CONFIG_TYPE$/etc/sysconfig/mail
Displays detailed information about a variable:
tux >
sudo
yast sysconfig details variable=POSTFIX_LISTEN Description: Value: File: /etc/sysconfig/postfix Possible Values: Any value Default Value: Configuration Script: postfix Description: Comma separated list of IP's NOTE: If not set, LISTEN on all interfaces
Displays summary of modified variables. Use all
to
list all variables and their values:
tux >
sudo
yast sysconfig list all AOU_AUTO_AGREE_WITH_LICENSES="false" AOU_ENABLE_CRONJOB="true" AOU_INCLUDE_RECOMMENDS="false" [...]
Sets a value for a variable:
tux >
sudo
yast sysconfig set DISPLAYMANAGER=gdm
If the variable is available in several files, use the VARIABLE_NAME$FILE_NAME syntax:
tux >
sudo
yast sysconfig set CONFIG_TYPE$/etc/sysconfig/mail=advanced
Configures a TFTP server. yast tftp-server
accepts the
following commands:
Specifies the directory of the TFTP server:
tux >
sudo
yast tftp-server directory path=/srv/tftptux >
sudo
yast tftp-server directory list Directory Path: /srv/tftp
Controls the status of the TFTP server service:
tux >
sudo
yast tftp-server status disabletux >
sudo
yast tftp-server status show Service Status: falsetux >
sudo
yast tftp-server status enable
Configures the time zone. yast timezone
accepts the
following commands:
Lists all available time zones grouped by region:
tux >
sudo
yast timezone list Region: Africa Africa/Abidjan (Abidjan) Africa/Accra (Accra) Africa/Addis_Ababa (Addis Ababa) [...]
Specifies new values for the time zone configuration:
tux >
sudo
yast timezone set timezone=Europe/Prague hwclock=local
Displays the time zone configuration summary:
tux >
sudo
yast timezone summary Current Time Zone: Europe/Prague Hardware Clock Set To: Local time Current Time and Date: Mon 12. March 2018, 11:36:21 CET
Manages user accounts. yast users
accepts the following
commands:
Adds a new user:
tux >
sudo
yast users add username=user1 password=secret home=/home/user1
For a complete list of options, run yast users add help
.
Deletes an existing user account:
tux >
sudo
yast users delete username=user1 delete_home
For a complete list of options, run yast users delete help
.
Changes an existing user account:
tux >
sudo
yast users edit username=user1 password=new_secret
For a complete list of options, run yast users edit help
.
Lists existing users filtered by user type:
tux >
sudo
yast users list system
For a complete list of options, run yast users list help
.
Displays details about a user:
tux >
sudo
yast users show username=wwwrun Full Name: WWW daemon apache List of Groups: www Default Group: wwwrun Home Directory: /var/lib/wwwrun Login Shell: /sbin/nologin Login Name: wwwrun UID: 456
For a complete list of options, run yast users show help
.
This chapter describes Zypper and RPM, two command line tools for managing
software. For a definition of the terminology used in this context (for
example, repository
, patch
, or
update
) refer to
Book “Start-Up”, Chapter 10 “Installing or Removing Software”, Section 10.1 “Definition of Terms”.
Zypper is a command line package manager for installing, updating and removing packages. It also manages repositories. It is especially useful for accomplishing remote software management tasks or managing software from shell scripts.
The general syntax of Zypper is:
zypper[--global-options]
COMMAND[--command-options]
[arguments]
The components enclosed in brackets are not required. See zypper
help
for a list of general options and all commands. To get help
for a specific command, type zypper help
COMMAND.
The simplest way to execute Zypper is to type its name, followed by a command. For example, to apply all needed patches to the system, use:
tux >
sudo
zypper patch
Additionally, you can choose from one or more global options by typing them immediately before the command:
tux >
sudo
zypper --non-interactive patch
In the above example, the option --non-interactive
means
that the command is run without asking anything (automatically applying
the default answers).
To use options that are specific to a particular command, type them immediately after the command:
tux >
sudo
zypper patch --auto-agree-with-licenses
In the above example, --auto-agree-with-licenses
is used
to apply all needed patches to a system without you being asked to
confirm any licenses. Instead, license will be accepted automatically.
Some commands require one or more arguments. For example, when using the
command install
, you need to specify which package or
which packages you want to install:
tux >
sudo
zypper install mplayer
Some options also require a single argument. The following command will list all known patterns:
tux >
zypper search -t pattern
You can combine all of the above. For example, the following command will
install the mc and vim packages from
the factory
repository while being verbose:
tux >
sudo
zypper -v install --from factory mc vim
The --from
option keeps all repositories
enabled (for solving any dependencies) while requesting the package from the
specified repository. --repo
is an alias for --from
, and you may use either one.
Most Zypper commands have a dry-run
option that does a
simulation of the given command. It can be used for test purposes.
tux >
sudo
zypper remove --dry-run MozillaFirefox
Zypper supports the global --userdata
STRING
option. You can specify a string
with this option, which gets written to Zypper's log files and plug-ins
(such as the Btrfs plug-in). It can be used to mark and identify
transactions in log files.
tux >
sudo
zypper --userdata STRING patch
Zypper subcommands are executables that are stored in the zypper_execdir,
/usr/lib/zypper/commands
. If a subcommand is not found
in the zypper_execdir, Zypper automatically searches the rest of your $PATH
for it. This enables writing your own local extensions and storing them in
userspace.
Executing subcommands in the Zypper shell, and using global Zypper options are not supported.
List your available subcommands:
tux >
zypper help subcommand
[...]
Available zypper subcommands in '/usr/lib/zypper/commands'
appstream-cache
lifecycle
migration
search-packages
Zypper subcommands available from elsewhere on your $PATH
<none>
View the help screen for a subcommand:
tux >
zypper help appstream-cache
To install or remove packages, use the following commands:
tux >
sudo
zypper install PACKAGE_NAMEtux >
sudo
zypper remove PACKAGE_NAME
Do not remove mandatory system packages like glibc , zypper , kernel . If they are removed, the system can become unstable or stop working altogether.
There are various ways to address packages with the commands
zypper install
and zypper remove
.
tux >
sudo
zypper install MozillaFirefox
tux >
sudo
zypper install MozillaFirefox-52.2
tux >
sudo
zypper install mozilla:MozillaFirefox
Where mozilla
is the alias of the repository from
which to install.
You can select all packages that have names starting or ending with a certain string. Use wild cards with care, especially when removing packages. The following command will install all packages starting with “Moz”:
tux >
sudo
zypper install 'Moz*'
-debuginfo
Packages
When debugging a problem, you sometimes need to temporarily install a
lot of -debuginfo
packages which give you more
information about running processes. After your debugging session
finishes and you need to clean the environment, run the following:
tux >
sudo
zypper remove '*-debuginfo'
For example, to install a package without knowing its name, capabilities come in handy. The following command will install the package MozillaFirefox:
tux >
sudo
zypper install firefox
Together with a capability, you can specify a hardware architecture and a version:
The name of the desired hardware architecture is appended to the
capability after a full stop. For example, to specify the AMD64/Intel 64
architectures (which in Zypper is named x86_64
),
use:
tux >
sudo
zypper install 'firefox.x86_64'
Versions must be appended to the end of the string and must be
preceded by an operator: <
(lesser than),
<=
(lesser than or equal), =
(equal), >=
(greater than or equal),
>
(greater than).
tux >
sudo
zypper install 'firefox>=74.2'
You can also combine a hardware architecture and version requirement:
tux >
sudo
zypper install 'firefox.x86_64>=74.2'
You can also specify a local or remote path to a package:
tux >
sudo
zypper install /tmp/install/MozillaFirefox.rpmtux >
sudo
zypper install http://download.example.com/MozillaFirefox.rpm
To install and remove packages simultaneously, use the
+/-
modifiers. To install emacs and
simultaneously remove vim , use:
tux >
sudo
zypper install emacs -vim
To remove emacs and simultaneously install vim , use:
tux >
sudo
zypper remove emacs +vim
To prevent the package name starting with the -
being
interpreted as a command option, always use it as the second argument. If
this is not possible, precede it with --
:
tux >
sudo
zypper install -emacs +vim # Wrongtux >
sudo
zypper install vim -emacs # Correcttux >
sudo
zypper install -- -emacs +vim # Correcttux >
sudo
zypper remove emacs +vim # Correct
If (together with a certain package), you automatically want to remove any
packages that become unneeded after removing the specified package, use the
--clean-deps
option:
tux >
sudo
zypper rm --clean-deps PACKAGE_NAME
By default, Zypper asks for a confirmation before installing or removing a
selected package, or when a problem occurs. You can override this behavior
using the --non-interactive
option. This option must be
given before the actual command (install
,
remove
, and patch
), as can be seen in
the following:
tux >
sudo
zypper--non-interactive
install PACKAGE_NAME
This option allows the use of Zypper in scripts and cron jobs.
To install the corresponding source package of a package, use:
tux >
zypper source-install PACKAGE_NAME
When executed as root
, the default location to install source
packages is /usr/src/packages/
and
~/rpmbuild
when run as user. These values can be
changed in your local rpm
configuration.
This command will also install the build dependencies of the specified
package. If you do not want this, add the switch -D
:
tux >
sudo
zypper source-install -D PACKAGE_NAME
To install only the build dependencies use -d
.
tux >
sudo
zypper source-install -d PACKAGE_NAME
Of course, this will only work if you have the repository with the source packages enabled in your repository list (it is added by default, but not enabled). See Section 2.1.6, “Managing Repositories with Zypper” for details on repository management.
A list of all source packages available in your repositories can be obtained with:
tux >
zypper search -t srcpackage
You can also download source packages for all installed packages to a local directory. To download source packages, use:
tux >
zypper source-download
The default download directory is
/var/cache/zypper/source-download
. You can change it
using the --directory
option. To only show missing or
extraneous packages without downloading or deleting anything, use the
--status
option. To delete extraneous source packages, use
the --delete
option. To disable deleting, use the
--no-delete
option.
Normally you can only install or refresh packages from enabled
repositories. The --plus-content
TAG
option helps you specify
repositories to be refreshed, temporarily enabled during the current Zypper
session, and disabled after it completes.
For example, to enable repositories that may provide additional
-debuginfo
or -debugsource
packages, use --plus-content debug
. You can specify this
option multiple times.
To temporarily enable such 'debug' repositories to install a specific
-debuginfo
package, use the option as follows:
tux >
sudo
zypper --plus-content debug \ install "debuginfo(build-id)=eb844a5c20c70a59fc693cd1061f851fb7d046f4"
The build-id
string is reported by
gdb
for missing debuginfo packages.
Repositories from the openSUSE Leap installation media are still
configured but disabled after successful installation. You can use the
--plus-content
option to install packages from the
installation media instead of the online repositories. Before calling
zypper
, ensure the media is available, for example by
inserting the DVD into the computer's drive.
To verify whether all dependencies are still fulfilled and to repair missing dependencies, use:
tux >
zypper verify
In addition to dependencies that must be fulfilled, some packages “recommend” other packages. These recommended packages are only installed if actually available and installable. In case recommended packages were made available after the recommending package has been installed (by adding additional packages or hardware), use the following command:
tux >
sudo
zypper install-new-recommends
This command is very useful after plugging in a Web cam or Wi-Fi device. It will install drivers for the device and related software, if available. Drivers and related software are only installable if certain hardware dependencies are fulfilled.
There are three different ways to update software using Zypper: by
installing patches, by installing a new version of a package or by updating
the entire distribution. The latter is achieved with zypper
dist-upgrade
. Upgrading openSUSE Leap is discussed in
Book “Start-Up”, Chapter 13 “Upgrading the System and System Changes”.
To install all officially released patches that apply to your system, run:
tux >
sudo
zypper patch
All patches available from repositories configured on your computer are
checked for their relevance to your installation. If they are relevant (and
not classified as optional
or
feature
), they are installed immediately.
If a patch that is about to be installed includes changes that require a system reboot, you will be warned before.
The plain zypper patch
command does not apply patches
from third party repositories. To update also the third party repositories,
use the with-update
command option as follows:
tux >
sudo
zypper patch --with-update
To install also optional patches, use:
tux >
sudo
zypper patch --with-optional
To install all patches relating to a specific Bugzilla issue, use:
tux >
sudo
zypper patch --bugzilla=NUMBER
To install all patches relating to a specific CVE database entry, use:
tux >
sudo
zypper patch --cve=NUMBER
For example, to install a security patch with the CVE number
CVE-2010-2713
, execute:
tux >
sudo
zypper patch --cve=CVE-2010-2713
To install only patches which affect Zypper and the package management itself, use:
tux >
sudo
zypper patch --updatestack-only
Bear in mind that other command options that would also update other
repositories will be dropped if you use the
updatestack-only
command option.
To find out whether patches are available, Zypper allows viewing the following information:
To list the number of needed patches (patches that apply to your system
but are not yet installed), use patch-check
:
tux >
zypper patch-check
Loading repository data...
Reading installed packages...
5 patches needed (1 security patch)
This command can be combined with the
--updatestack-only
option to list only the patches
which affect Zypper and the package management itself.
To list all needed patches (patches that apply to your system but are
not yet installed), use list-patches
:
tux >
zypper list-patches
Repository | Name | Category | Severity | Interactive | Status | S>
-----------+-------------------+----------+----------+-------------+--------+-->
Update | openSUSE-2019-828 | security | moderate | --- | needed | S>
Found 1 applicable patch:
1 patch needed (1 security patch)
Note the new Since
column. From Zypper 1.14.36, this shows when a patch
was installed.
To list all patches available for openSUSE Leap, regardless of whether
they are already installed or apply to your installation, use
zypper patches
.
It is also possible to list and install patches relevant to specific
issues. To list specific patches, use the zypper
list-patches
command with the following options:
To list all needed patches that relate to Bugzilla issues, use the
option --bugzilla
.
To list patches for a specific bug, you can also specify a bug number:
--bugzilla=NUMBER
. To search
for patches relating to multiple Bugzilla issues, add commas between the
bug numbers, for example:
tux >
zypper list-patches --bugzilla=972197,956917
To list all needed patches that relate to an entry in the CVE database
(Common Vulnerabilities and Exposures), use the option
--cve
.
To list patches for a specific CVE database entry, you can also specify
a CVE number: --cve=NUMBER
.
To search for patches relating to multiple CVE database entries, add
commas between the CVE numbers, for example:
tux >
zypper list-patches --bugzilla=CVE-2016-2315,CVE-2016-2324
To list all patches regardless of whether they are needed, use the option
--all
additionally. For example, to list all patches with
a CVE number assigned, use:
tux >
zypper list-patches --all --cve
Issue | No. | Patch | Category | Severity | Status
------+---------------+-------------------+-------------+-----------+----------
cve | CVE-2019-0287 | SUSE-SLE-Module.. | recommended | moderate | needed
cve | CVE-2019-3566 | SUSE-SLE-SERVER.. | recommended | moderate | not needed
[...]
If a repository contains only new packages, but does not provide patches,
zypper patch
does not show any effect. To update
all installed packages with newer available versions (while maintaining
system integrity), use:
tux >
sudo
zypper update
To update individual packages, specify the package with either the update or install command:
tux >
sudo
zypper update PACKAGE_NAMEtux >
sudo
zypper install PACKAGE_NAME
A list of all new installable packages can be obtained with the command:
tux >
zypper list-updates
Note that this command only lists packages that match the following criteria:
has the same vendor like the already installed package,
is provided by repositories with at least the same priority than the already installed package,
is installable (all dependencies are satisfied).
A list of all new available packages (regardless whether installable or not) can be obtained with:
tux >
sudo
zypper list-updates --all
To find out why a new package cannot be installed, use the zypper
install
or zypper update
command as described
above.
Whenever you remove a repository from Zypper or upgrade your system, some packages can get in an “orphaned” state. These orphaned packages belong to no active repository anymore. The following command gives you a list of these:
tux >
sudo
zypper packages --orphaned
With this list, you can decide if a package is still needed or can be removed safely.
When patching, updating or removing packages, there may be running processes
on the system which continue to use files having been deleted by the update
or removal. Use zypper ps
to list processes using deleted
files. In case the process belongs to a known service, the service name is
listed, making it easy to restart the service. By default zypper
ps
shows a table:
tux >
zypper ps
PID | PPID | UID | User | Command | Service | Files
------+------+-----+-------+--------------+--------------+-------------------
814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon | /lib64/ld-2.19.s->
| | | | | | /lib64/libdl-2.1->
| | | | | | /lib64/libpthrea->
| | | | | | /lib64/libc-2.19->
[...]
PID: ID of the process |
PPID: ID of the parent process |
UID: ID of the user running the process |
Login: Login name of the user running the process |
Command: Command used to execute the process |
Service: Service name (only if command is associated with a system service) |
Files: The list of the deleted files |
The output format of zypper ps
can be controlled as
follows:
zypper ps
-s
Create a short table not showing the deleted files.
tux >
zypper ps -s
PID | PPID | UID | User | Command | Service
------+------+------+---------+--------------+--------------
814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon
817 | 1 | 0 | root | irqbalance | irqbalance
1567 | 1 | 0 | root | sshd | sshd
1761 | 1 | 0 | root | master | postfix
1764 | 1761 | 51 | postfix | pickup | postfix
1765 | 1761 | 51 | postfix | qmgr | postfix
2031 | 2027 | 1000 | tux | bash |
zypper ps
-ss
Show only processes associated with a system service.
PID | PPID | UID | User | Command | Service ------+------+------+---------+--------------+-------------- 814 | 1 | 481 | avahi | avahi-daemon | avahi-daemon 817 | 1 | 0 | root | irqbalance | irqbalance 1567 | 1 | 0 | root | sshd | sshd 1761 | 1 | 0 | root | master | postfix 1764 | 1761 | 51 | postfix | pickup | postfix 1765 | 1761 | 51 | postfix | qmgr | postfix
zypper ps
-sss
Only show system services using deleted files.
avahi-daemon irqbalance postfix sshd
zypper ps
--print "systemctl status %s"
Show the commands to retrieve status information for services which might need a restart.
systemctl status avahi-daemon systemctl status irqbalance systemctl status postfix systemctl status sshd
For more information about service handling refer to
Chapter 10, The systemd
Daemon.
All installation or patch commands of Zypper rely on a list of known repositories. To list all repositories known to the system, use the command:
tux >
zypper repos
The result will look similar to the following output:
tux >
zypper repos
# | Alias | Name | Enabled | GPG Check | Refresh
---+-----------------------+------------------+---------+-----------+--------
1 | Leap-15.1-Main | Main (OSS) | Yes | (r ) Yes | Yes
2 | Leap-15.1-Update | Update (OSS) | Yes | (r ) Yes | Yes
3 | Leap-15.1-NOSS | Main (NON-OSS) | Yes | (r ) Yes | Yes
4 | Leap-15.1-Update-NOSS | Update (NON-OSS) | Yes | (r ) Yes | Yes
[...]
When specifying repositories in various commands, an alias, URI or
repository number from the zypper repos
command output
can be used. A repository alias is a short version of the repository name
for use in repository handling commands. Note that the repository numbers
can change after modifying the list of repositories. The alias will never
change by itself.
By default, details such as the URI or the priority of the repository are not displayed. Use the following command to list all details:
tux >
zypper repos -d
To add a repository, run
tux >
sudo
zypper addrepo URI ALIAS
URI can either be an Internet repository, a network resource, a directory or a CD or DVD (see http://en.opensuse.org/openSUSE:Libzypp_URIs for details). The ALIAS is a shorthand and unique identifier of the repository. You can freely choose it, with the only exception that it needs to be unique. Zypper will issue a warning if you specify an alias that is already in use.
zypper
enables you to fetch changes in packages from
configured repositories. To fetch the changes, run:
tux >
sudo
zypper refresh
zypper
By default, some commands perform refresh
automatically, so you do not need to run the command explicitly.
The refresh
command enables you to view changes also in
disabled repositories, by using the --plus-content
option:
tux >
sudo
zypper --plus-content refresh
This option fetches changes in repositories, but keeps the disabled repositories in the same state—disabled.
To remove a repository from the list, use the command zypper
removerepo
together with the alias or number of the repository
you want to delete. For example, to remove the repository
Leap-42.3-NOSS
from Example 2.1, “Zypper—List of Known Repositories”, use one of the following commands:
tux >
sudo
zypper removerepo 4tux >
sudo
zypper removerepo "Leap-42.3-NOSS"
Enable or disable repositories with zypper modifyrepo
.
You can also alter the repository's properties (such as refreshing
behavior, name or priority) with this command. The following command will
enable the repository named updates
, turn on
auto-refresh and set its priority to 20:
tux >
sudo
zypper modifyrepo -er -p 20 'updates'
Modifying repositories is not limited to a single repository—you can also operate on groups:
-a : all repositories |
-l : local repositories |
-t : remote repositories |
-m TYPE : repositories
of a certain type (where TYPE can be one of the
following: http , https , ftp ,
cd , dvd , dir , file ,
cifs , smb , nfs , hd ,
iso ) |
To rename a repository alias, use the renamerepo
command. The following example changes the alias from Mozilla
Firefox
to firefox
:
tux >
sudo
zypper renamerepo 'Mozilla Firefox' firefox
Zypper offers various methods to query repositories or packages. To get lists of all products, patterns, packages or patches available, use the following commands:
tux >
zypper productstux >
zypper patternstux >
zypper packagestux >
zypper patches
To query all repositories for certain packages, use
search
. To get information regarding particular packages,
use the info
command.
The zypper search
command works on package names, or,
optionally, on package summaries and descriptions. Strings wrapped in
/
are interpreted as regular expressions. By default,
the search is not case-sensitive.
fire
tux >
zypper search "fire"
MozillaFirefox
tux >
zypper search --match-exact "MozillaFirefox"
tux >
zypper search -d fire
tux >
zypper search -u fire
fir
not followed be e
tux >
zypper se "/fir[^e]/"
To search for packages which provide a special capability, use the command
what-provides
. For example, if you want to know which
package provides the Perl module SVN::Core
, use the
following command:
tux >
zypper what-provides 'perl(SVN::Core)'
The what-provides
PACKAGE_NAME
is similar to
rpm -q --whatprovides
PACKAGE_NAME, but RPM is only able to query the
RPM database (that is the database of all installed packages). Zypper, on
the other hand, will tell you about providers of the capability from any
repository, not only those that are installed.
To query single packages, use info
with an exact package
name as an argument. This displays detailed information about a package. In
case the package name does not match any package name from repositories,
the command outputs detailed information for non-package matches. If you
request a specific type (by using the -t
option) and the
type does not exist, the command outputs other available matches but
without detailed information.
If you specify a source package, the command displays binary packages built from the source package. If you specify a binary package, the command outputs the source packages used to build the binary package.
To also show what is required/recommended by the package, use the options
--requires
and --recommends
:
tux >
zypper info --requires MozillaFirefox
Zypper now comes with a configuration file, allowing you to permanently
change Zypper's behavior (either system-wide or user-specific). For
system-wide changes, edit /etc/zypp/zypper.conf
. For
user-specific changes, edit ~/.zypper.conf
. If
~/.zypper.conf
does not yet exist, you can use
/etc/zypp/zypper.conf
as a template: copy it to
~/.zypper.conf
and adjust it to your liking. Refer to
the comments in the file for help about the available options.
If you have trouble accessing packages from configured repositories (for example, Zypper cannot find a certain package even though you know it exists in one of the repositories), refreshing the repositories may help:
tux >
sudo
zypper refresh
If that does not help, try
tux >
sudo
zypper refresh -fdb
This forces a complete refresh and rebuild of the database, including a forced download of raw metadata.
If the Btrfs file system is used on the root partition and
snapper
is installed, Zypper automatically calls
snapper
when committing changes to the file system to
create appropriate file system snapshots. These snapshots can be used to
revert any changes made by Zypper. See Chapter 3, System Recovery and Snapshot Management with Snapper for
more information.
For more information on managing software from the command line, enter
zypper help
, zypper help
COMMAND or refer to the
zypper(8)
man page. For a complete and detailed command
reference, cheat sheets
with the most important commands,
and information on how to use Zypper in scripts and applications, refer to
http://en.opensuse.org/SDB:Zypper_usage. A list of
software changes for the latest openSUSE Leap version can be found at
http://en.opensuse.org/openSUSE:Zypper versions.
RPM (RPM Package Manager) is used for managing software packages. Its main
commands are rpm
and rpmbuild
. The
powerful RPM database can be queried by the users, system administrators and
package builders for detailed information about the installed software.
rpm
has five modes: installing, uninstalling
(or updating) software packages, rebuilding the RPM database, querying RPM
bases or individual RPM archives, integrity checking of packages and signing
packages. rpmbuild
can be used to build installable
packages from pristine sources.
Installable RPM archives are packed in a special binary format. These
archives consist of the program files to install and certain meta information
used during the installation by rpm
to configure the
software package or stored in the RPM database for documentation purposes.
RPM archives normally have the extension .rpm
.
For several packages, the components needed for software development
(libraries, headers, include files, etc.) have been put into separate
packages. These development packages are only needed if you want to compile
software yourself (for example, the most recent GNOME packages). They can
be identified by the name extension -devel
, such as the
packages alsa-devel
and
gimp-devel
.
RPM packages have a GPG signature. To verify the signature of an RPM
package, use the command rpm --checksig
PACKAGE-1.2.3.rpm to determine whether the
package originates from SUSE or from another trustworthy facility. This is
especially recommended for update packages from the Internet.
Normally, the installation of an RPM archive is quite simple: rpm
-i
PACKAGE.rpm. With this command the
package is installed, but only if its dependencies are fulfilled and if
there are no conflicts with other packages. With an error message,
rpm
requests those packages that need to be installed to
meet dependency requirements. In the background, the RPM database ensures
that no conflicts arise—a specific file can only belong to one
package. By choosing different options, you can force rpm
to ignore these defaults, but this is only for experts. Otherwise, you risk
compromising the integrity of the system and possibly jeopardize the ability
to update the system.
The options -U
or --upgrade
and
-F
or --freshen
can be used to update a
package (for example, rpm -F
PACKAGE.rpm). This command removes the files of
the old version and immediately installs the new files. The difference
between the two versions is that -U
installs packages that
previously did not exist in the system, while -F
merely
updates previously installed packages. When updating, rpm
updates configuration files carefully using the following strategy:
If a configuration file was not changed by the system administrator,
rpm
installs the new version of the appropriate file.
No action by the system administrator is required.
If a configuration file was changed by the system administrator before the
update, rpm
saves the changed file with the extension
.rpmorig
or .rpmsave
(backup
file) and installs the version from the new package. This is done only if
the originally installed file and the newer version are different. If this is
the case, compare the backup file (.rpmorig
or
.rpmsave
) with the newly installed file and make your
changes again in the new file. Afterward, delete all
.rpmorig
and .rpmsave
files to
avoid problems with future updates.
.rpmnew
files appear if the configuration file
already exists and if the noreplace
label was specified in the .spec
file.
Following an update, .rpmsave
and
.rpmnew
files should be removed after comparing them,
so they do not obstruct future updates. The .rpmorig
extension is assigned if the file has not previously been recognized by the
RPM database.
Otherwise, .rpmsave
is used. In other words,
.rpmorig
results from updating from a foreign format to
RPM. .rpmsave
results from updating from an older RPM
to a newer RPM. .rpmnew
does not disclose any
information to whether the system administrator has made any changes to the
configuration file. A list of these files is available in
/var/adm/rpmconfigcheck
. Some configuration files (like
/etc/httpd/httpd.conf
) are not overwritten to allow
continued operation.
The -U
switch is not only an
equivalent to uninstalling with the -e
option and
installing with the -i
option. Use -U
whenever possible.
To remove a package, enter rpm -e
PACKAGE. This command only deletes the package if
there are no unresolved dependencies. It is theoretically impossible to
delete Tcl/Tk, for example, as long as another application requires it. Even
in this case, RPM calls for assistance from the database. If such a deletion
is, for whatever reason, impossible (even if no
additional dependencies exist), it may be helpful to rebuild the RPM
database using the option --rebuilddb
.
Delta RPM packages contain the difference between an old and a new version of an RPM package. Applying a delta RPM onto an old RPM results in a completely new RPM. It is not necessary to have a copy of the old RPM because a delta RPM can also work with an installed RPM. The delta RPM packages are even smaller in size than patch RPMs, which is an advantage when transferring update packages over the Internet. The drawback is that update operations with delta RPMs involved consume considerably more CPU cycles than plain or patch RPMs.
The makedeltarpm
and applydelta
binaries are part of the delta RPM suite (package
deltarpm
) and help you create and apply delta RPM
packages. With the following commands, you can create a delta RPM called
new.delta.rpm
. The following command assumes that
old.rpm
and new.rpm
are present:
tux >
sudo
makedeltarpm old.rpm new.rpm new.delta.rpm
Using applydeltarpm
, you can reconstruct the new RPM from
the file system if the old package is already installed:
tux >
sudo
applydeltarpm new.delta.rpm new.rpm
To derive it from the old RPM without accessing the file system, use the
-r
option:
tux >
sudo
applydeltarpm -r old.rpm new.delta.rpm new.rpm
See /usr/share/doc/packages/deltarpm/README
for
technical details.
With the -q
option rpm
initiates
queries, making it possible to inspect an RPM archive (by adding the option
-p
) and to query the RPM database of installed packages.
Several switches are available to specify the type of information required.
See Table 2.1, “The Most Important RPM Query Options”.
|
Package information |
|
File list |
|
Query the package that contains the file FILE (the full path must be specified with FILE) |
|
File list with status information (implies |
|
List only documentation files (implies |
|
List only configuration files (implies |
|
File list with complete details (to be used with |
|
List features of the package that another package can request with
|
|
Capabilities the package requires |
|
Installation scripts (preinstall, postinstall, uninstall) |
For example, the command rpm -q -i wget
displays the
information shown in Example 2.2, “rpm -q -i wget
”.
rpm -q -i wget
#Name : wget Name : wget Version : 1.19.5 Release : lp151.4.1 Architecture: x86_64 Install Date: Tue 30 Jul 2019 02:26:21 PM PDT Group : Productivity/Networking/Web/Utilities Size : 2881903 License : GPL-3.0+ Signature : RSA/SHA256, Thu 11 Apr 2019 02:23:42 AM PDT, Key ID b88b2fd43dbdc284 Source RPM : wget-1.19.5-lp151.4.1.src.rpm Build Date : Thu 11 Apr 2019 02:23:27 AM PDT Build Host : cloud114 Relocations : (not relocatable) Packager : https://bugs.opensuse.org Vendor : openSUSE URL : https://www.gnu.org/software/wget/ Summary : A Tool for Mirroring FTP and HTTP Servers Description : Wget enables you to retrieve WWW documents or FTP files from a server. This can be done in script files or via the command line. Distribution: openSUSE Leap 15.1
The option -f
only works if you specify the complete file
name with its full path. Provide as many file names as desired. For example:
tux >
rpm -q -f /bin/rpm /usr/bin/wget
rpm-4.14.1-lp151.13.10.x86_64
wget-1.19.5-lp151.4.1.x86_64
If only part of the file name is known, use a shell script as shown in Example 2.3, “Script to Search for Packages”. Pass the partial file name to the script shown as a parameter when running it.
#! /bin/sh for i in $(rpm -q -a -l | grep $1); do echo "\"$i\" is in package:" rpm -q -f $i echo "" done
The command rpm -q --changelog
PACKAGE displays a detailed list of change
information about a specific package, sorted by date.
With the installed RPM database, verification checks can be made. Initiate
these with -V
, or --verify
. With this
option, rpm
shows all files in a package that have been
changed since installation. rpm
uses eight character
symbols to give some hints about the following changes:
|
MD5 check sum |
|
File size |
|
Symbolic link |
|
Modification time |
|
Major and minor device numbers |
|
Owner |
|
Group |
|
Mode (permissions and file type) |
In the case of configuration files, the letter c
is
printed. For example, for changes to /etc/wgetrc
(wget
package):
tux >
rpm -V wget
S.5....T c /etc/wgetrc
The files of the RPM database are placed in
/var/lib/rpm
. If the partition
/usr
has a size of 1 GB, this database can occupy
nearly 30 MB, especially after a complete update. If the database is
much larger than expected, it is useful to rebuild the database with the
option --rebuilddb
. Before doing this, make a backup of the
old database. The cron
script
cron.daily
makes daily copies of the database (packed
with gzip) and stores them in /var/adm/backup/rpmdb
.
The number of copies is controlled by the variable
MAX_RPMDB_BACKUPS
(default: 5
) in
/etc/sysconfig/backup
. The size of a single backup is
approximately 1 MB for 1 GB in /usr
.
All source packages carry a .src.rpm
extension (source
RPM).
Source packages can be copied from the installation medium to the hard disk
and unpacked with YaST. They are not, however, marked as installed
([i]
) in the package manager. This is because the source
packages are not entered in the RPM database. Only
installed operating system software is listed in the
RPM database. When you “install” a source package, only the
source code is added to the system.
The following directories must be available for rpm
and
rpmbuild
in /usr/src/packages
(unless you specified custom settings in a file like
/etc/rpmrc
):
SOURCES
for the original sources (.tar.bz2
or
.tar.gz
files, etc.) and for distribution-specific
adjustments (mostly .diff
or
.patch
files)
SPECS
for the .spec
files, similar to a meta Makefile,
which control the build process
BUILD
all the sources are unpacked, patched and compiled in this directory
RPMS
where the completed binary packages are stored
SRPMS
here are the source RPMs
When you install a source package with YaST, all the necessary components
are installed in /usr/src/packages
: the sources and the
adjustments in SOURCES
and the relevant
.spec
file in SPECS
.
Do not experiment with system components
(glibc
,
rpm
, etc.), because this
endangers the stability of your system.
The following example uses the wget.src.rpm
package.
After installing the source package, you should have files similar to those
in the following list:
/usr/src/packages/SOURCES/wget-1.19.5.tar.bz2 /usr/src/packages/SOURCES/wgetrc.patch /usr/src/packages/SPECS/wget.spec
rpmbuild
-bX
/usr/src/packages/SPECS/wget.spec
starts the
compilation. X is a wild card for various stages
of the build process (see the output of --help
or the RPM
documentation for details). The following is merely a brief explanation:
-bp
Prepare sources in /usr/src/packages/BUILD
: unpack
and patch.
-bc
Do the same as -bp
, but with additional compilation.
-bi
Do the same as -bp
, but with additional installation of
the built software. Caution: if the package does not support the
BuildRoot feature, you might overwrite configuration files.
-bb
Do the same as -bi
, but with the additional creation of
the binary package. If the compile was successful, the binary should be
in /usr/src/packages/RPMS
.
-ba
Do the same as -bb
, but with the additional creation of
the source RPM. If the compilation was successful, the binary should be
in /usr/src/packages/SRPMS
.
--short-circuit
Skip some steps.
The binary RPM created can now be installed with rpm
-i
or, preferably, with rpm
-U
. Installation with rpm
makes it
appear in the RPM database.
Keep in mind, the BuildRoot
directive in the spec file is
deprecated since openSUSE Leap 42.1. If you still need this feature, use the
--buildroot
option as a workaround.
The danger with many packages is that unwanted files are added to the
running system during the build process. To prevent this use
build
, which creates a defined environment in which
the package is built. To establish this chroot environment, the
build
script must be provided with a complete package
tree. This tree can be made available on the hard disk, via NFS, or from
DVD. Set the position with build --rpms
DIRECTORY. Unlike rpm
, the
build
command looks for the .spec
file in the source directory. To build wget
(like in
the above example) with the DVD mounted in the system under
/media/dvd
, use the following commands as
root
:
root #
cd /usr/src/packages/SOURCES/root #
mv ../SPECS/wget.spec .root #
build --rpms /media/dvd/suse/ wget.spec
Subsequently, a minimum environment is established at
/var/tmp/build-root
. The package is built in this
environment. Upon completion, the resulting packages are located in
/var/tmp/build-root/usr/src/packages/RPMS
.
The build
script offers several additional options. For
example, cause the script to prefer your own RPMs, omit the initialization
of the build environment or limit the rpm
command to one
of the above-mentioned stages. Access additional information with
build
--help
and by reading the
build
man page.
Midnight Commander (mc
) can display the contents of RPM
archives and copy parts of them. It represents archives as virtual file
systems, offering all usual menu options of Midnight Commander. Display the
HEADER
with F3. View the archive
structure with the cursor keys and Enter. Copy archive
components with F5.
A full-featured package manager is available as a YaST module. For details, see Book “Start-Up”, Chapter 10 “Installing or Removing Software”.
Snapper allows creating and managing file system snapshots. File system snapshots allow keeping a copy of the state of a file system at a certain point of time. The standard setup of Snapper is designed to allow rolling back system changes. However, you can also use it to create on-disk backups of user data. As the basis for this functionality, Snapper uses the Btrfs file system or thinly-provisioned LVM volumes with an XFS or Ext4 file system.
Snapper has a command-line interface and a YaST interface. Snapper lets you create and manage file system snapshots on the following types of file systems:
Btrfs, a copy-on-write file system for Linux that natively supports file system snapshots of subvolumes. (Subvolumes are separately mountable file systems within a physical partition.)
You can also boot from Btrfs
snapshots. For more
information, see Section 3.3, “System Rollback by Booting from Snapshots”.
Thinly-provisioned LVM volumes formatted with XFS or Ext4.
Using Snapper, you can perform the following tasks:
Undo system changes made by zypper
and YaST. See
Section 3.2, “Using Snapper to Undo Changes” for details.
Restore files from previous snapshots. See Section 3.2.2, “Using Snapper to Restore Files” for details.
Do a system rollback by booting from a snapshot. See Section 3.3, “System Rollback by Booting from Snapshots” for details.
Manually create and manage snapshots, within the running system. See Section 3.6, “Manually Creating and Managing Snapshots” for details.
Snapper on openSUSE Leap is set up as an undo and recovery
tool for system changes. By default, the root partition
(/
) of openSUSE Leap is formatted with
Btrfs
. Taking snapshots is automatically enabled if the
root partition (/
) is big enough (more
than approximately 16 GB). By default, snapshots are disabled on partitions
other than /
.
If you disabled Snapper during the installation, you can enable it at any time later. To do so, create a default Snapper configuration for the root file system by running:
tux >
sudo
snapper -c root create-config /
Afterward enable the different snapshot types as described in Section 3.1.4.1, “Disabling/Enabling Snapshots”.
Note that on a Btrfs root file system, snapshots require a file system with subvolumes set up as proposed by the installer and a partition size of at least 16 GB.
When a snapshot is created, both the snapshot and the original point to the
same blocks in the file system. So, initially a snapshot does not occupy
additional disk space. If data in the original file system is modified,
changed data blocks are copied while the old data blocks are kept for the
snapshot. Therefore, a snapshot occupies the same amount of space as the
data modified. So, over time, the amount of space a snapshot allocates,
constantly grows. As a consequence, deleting files from a
Btrfs
file system containing snapshots may
not free disk space!
Snapshots always reside on the same partition or subvolume on which the snapshot has been taken. It is not possible to store snapshots on a different partition or subvolume.
As a result, partitions containing snapshots need to be larger than partitions not containing snapshots. The exact amount depends strongly on the number of snapshots you keep and the amount of data modifications. As a rule of thumb, give partitions twice as much space as you normally would. To prevent disks from running out of space, old snapshots are automatically cleaned up. Refer to Section 3.1.4.4, “Controlling Snapshot Archiving” for details.
Configuration file: /etc/snapper/configs/root
USE_SNAPPER=yes
TIMELINE_CREATE=no
Configuration file: not created
USE_SNAPPER=no
TIMELINE_CREATE=yes
Although snapshots themselves do not differ in a technical sense, we distinguish between three types of snapshots, based on the events that trigger them:
A single snapshot is created every hour. Old snapshots are automatically deleted. By default, the first snapshot of the last ten days, months, and years are kept. Timeline snapshots are disabled by default.
Whenever one or more packages are installed with YaST or Zypper, a
pair of snapshots is created: one before the installation starts
(“Pre”) and another one after the installation has finished
(“Post”). In case an important system component such as the
kernel has been installed, the snapshot pair is marked as important
(important=yes
). Old snapshots are automatically
deleted. By default the last ten important snapshots and the last ten
“regular” (including administration snapshots) snapshots
are kept. Installation snapshots are enabled by default.
Whenever you administrate the system with YaST, a pair of snapshots is created: one when a YaST module is started (“Pre”) and another when the module is closed (“Post”). Old snapshots are automatically deleted. By default the last ten important snapshots and the last ten “regular” snapshots (including installation snapshots) are kept. Administration snapshots are enabled by default.
Some directories need to be excluded from snapshots for different reasons. The following list shows all directories that are excluded:
/boot/grub2/i386-pc
,
/boot/grub2/x86_64-efi
,
/boot/grub2/powerpc-ieee1275
,
/boot/grub2/s390x-emu
A rollback of the boot loader configuration is not supported. The directories listed above are architecture-specific. The first two directories are present on AMD64/Intel 64 machines, the latter two on IBM POWER and on IBM Z, respectively.
/home
If /home
does not reside on a separate partition, it
is excluded to avoid data loss on rollbacks.
/opt
Third-party products usually get installed to /opt
. It
is excluded to avoid uninstalling these applications on rollbacks.
/srv
Contains data for Web and FTP servers. It is excluded to avoid data loss on rollbacks.
/tmp
All directories containing temporary files and caches are excluded from snapshots.
/usr/local
This directory is used when manually installing software. It is excluded to avoid uninstalling these installations on rollbacks.
/var
This directory contains many variable files, including logs, temporary
caches, third party products in /var/opt
, and is the
default location for virtual machine images and databases. Therefore this
subvolume is created to exclude all of this variable data from snapshots
and has Copy-On-Write disabled.
openSUSE Leap comes with a reasonable default setup, which should be sufficient for most use cases. However, all aspects of taking automatic snapshots and snapshot keeping can be configured according to your needs.
Each of the three snapshot types (timeline, installation, administration) can be enabled or disabled independently.
Enabling.
snapper -c root set-config "TIMELINE_CREATE=yes"
Disabling.
snapper -c root set-config "TIMELINE_CREATE=no"
Timeline snapshots are enabled by default, except for the root partition.
Enabling:
Install the package
snapper-zypp-plugin
Disabling:
Uninstall the package
snapper-zypp-plugin
Installation snapshots are enabled by default.
Enabling:
Set USE_SNAPPER
to yes
in
/etc/sysconfig/yast2
.
Disabling:
Set USE_SNAPPER
to no
in
/etc/sysconfig/yast2
.
Administration snapshots are enabled by default.
Taking snapshot pairs upon installing packages with YaST or Zypper is
handled by the
snapper-zypp-plugin
. An XML
configuration file, /etc/snapper/zypp-plugin.conf
defines, when to make snapshots. By default the file looks like the
following:
1 <?xml version="1.0" encoding="utf-8"?> 2 <snapper-zypp-plugin-conf> 3 <solvables> 4 <solvable match="w"1 important="true"2>kernel-*3</solvable> 5 <solvable match="w" important="true">dracut</solvable> 6 <solvable match="w" important="true">glibc</solvable> 7 <solvable match="w" important="true">systemd*</solvable> 8 <solvable match="w" important="true">udev</solvable> 9 <solvable match="w">*</solvable>4 10 </solvables> 11 </snapper-zypp-plugin-conf>
The match attribute defines whether the pattern is a Unix shell-style
wild card ( | |
If the given pattern matches and the corresponding package is marked as important (for example kernel packages), the snapshot will also be marked as important. | |
Pattern to match a package name. Based on the setting of the
| |
This line unconditionally matches all packages. |
With this configuration snapshot, pairs are made whenever a package is installed (line 9). When the kernel, dracut, glibc, systemd, or udev packages marked as important are installed, the snapshot pair will also be marked as important (lines 4 to 8). All rules are evaluated.
To disable a rule, either delete it or deactivate it using XML comments. To prevent the system from making snapshot pairs for every package installation for example, comment line 9:
1 <?xml version="1.0" encoding="utf-8"?> 2 <snapper-zypp-plugin-conf> 3 <solvables> 4 <solvable match="w" important="true">kernel-*</solvable> 5 <solvable match="w" important="true">dracut</solvable> 6 <solvable match="w" important="true">glibc</solvable> 7 <solvable match="w" important="true">systemd*</solvable> 8 <solvable match="w" important="true">udev</solvable> 9 <!-- <solvable match="w">*</solvable> --> 10 </solvables> 11 </snapper-zypp-plugin-conf>
Creating a new subvolume underneath the /
hierarchy
and permanently mounting it is supported. Such a subvolume will be
excluded from snapshots. You need to make sure not to create it inside an
existing snapshot, since you would not be able to delete snapshots anymore
after a rollback.
openSUSE Leap is configured with the /@/
subvolume
which serves as an independent root for permanent subvolumes such as
/opt
, /srv
,
/home
and others. Any new subvolumes you create and
permanently mount need to be created in this initial root file system.
To do so, run the following commands. In this example, a new subvolume
/usr/important
is created from
/dev/sda2
.
tux >
sudo
mount /dev/sda2 -o subvol=@ /mnttux >
sudo
btrfs subvolume create /mnt/usr/importanttux >
sudo
umount /mnt
The corresponding entry in /etc/fstab
needs to look
like the following:
/dev/sda2 /usr/important btrfs subvol=@/usr/important 0 0
A subvolume may contain files that constantly change, such as
virtualized disk images, database files, or log files. If so, consider
disabling the copy-on-write feature for this volume, to avoid duplication
of disk blocks. Use the nodatacow
mount option in
/etc/fstab
to do so:
/dev/sda2 /usr/important btrfs nodatacow,subvol=@/usr/important 0 0
To alternatively disable copy-on-write for single files or directories,
use the command chattr +C
PATH
.
Snapshots occupy disk space. To prevent disks from running out of space and thus causing system outages, old snapshots are automatically deleted. By default, up to ten important installation and administration snapshots and up to ten regular installation and administration snapshots are kept. If these snapshots occupy more than 50% of the root file system size, additional snapshots will be deleted. A minimum of four important and two regular snapshots are always kept.
Refer to Section 3.5.1, “Managing Existing Configurations” for instructions on how to change these values.
Apart from snapshots on Btrfs
file systems, Snapper
also supports taking snapshots on thinly-provisioned LVM volumes (snapshots
on regular LVM volumes are not supported) formatted
with XFS, Ext4 or Ext3. For more information and setup instructions on LVM
volumes, refer to Section 5.2, “LVM Configuration”.
To use Snapper on a thinly-provisioned LVM volume you need to create a
Snapper configuration for it. On LVM it is required to specify the file
system with
--fstype=lvm(FILESYSTEM)
.
ext3
, etx4
or xfs
are valid values for FILESYSTEM. Example:
tux >
sudo
snapper -c lvm create-config --fstype="lvm(xfs)" /thin_lvm
You can adjust this configuration according to your needs as described in Section 3.5.1, “Managing Existing Configurations”.
Snapper on openSUSE Leap is preconfigured to serve as a tool that lets you
undo changes made by zypper
and YaST. For this purpose,
Snapper is configured to create a pair of snapshots before and after each
run of zypper
and YaST. Snapper also lets you restore
system files that have been accidentally deleted or modified. Timeline
snapshots for the root partition need to be enabled for this
purpose—see
Section 3.1.4.1, “Disabling/Enabling Snapshots” for details.
By default, automatic snapshots as described above are configured for the
root partition and its subvolumes. To make snapshots available for other
partitions such as /home
for example, you can create
custom configurations.
When working with snapshots to restore data, it is important to know that there are two fundamentally different scenarios Snapper can handle:
When undoing changes as described in the following, two snapshots are being compared and the changes between these two snapshots are made undone. Using this method also allows to explicitly select the files that should be restored.
When doing rollbacks as described in Section 3.3, “System Rollback by Booting from Snapshots”, the system is reset to the state at which the snapshot was taken.
When undoing changes, it is also possible to compare a snapshot against the current system. When restoring all files from such a comparison, this will have the same result as doing a rollback. However, using the method described in Section 3.3, “System Rollback by Booting from Snapshots” for rollbacks should be preferred, since it is faster and allows you to review the system before doing the rollback.
There is no mechanism to ensure data consistency when creating a snapshot.
Whenever a file (for example, a database) is written at the same time as
the snapshot is being created, it will result in a corrupted or partly written
file. Restoring such a file will cause problems. Furthermore, some system
files such as /etc/mtab
must never be restored.
Therefore it is strongly recommended to always closely
review the list of changed files and their diffs. Only restore files that
really belong to the action you want to revert.
If you set up the root partition with Btrfs
during the
installation, Snapper—preconfigured for doing rollbacks of YaST or
Zypper changes—will automatically be installed. Every time you start
a YaST module or a Zypper transaction, two snapshots are created: a
“pre-snapshot” capturing the state of the file system before
the start of the module and a “post-snapshot” after the module
has been finished.
Using the YaST Snapper module or the snapper
command
line tool, you can undo the changes made by YaST/Zypper by restoring
files from the “pre-snapshot”. Comparing two snapshots the
tools also allow you to see which files have been changed. You can also
display the differences between two versions of a file (diff).
Start the yast2 snapper
.
Make sure
is set to . This is always the case unless you have manually added own Snapper configurations.
Choose a pair of pre- and post-snapshots from the list. Both, YaST and
Zypper snapshot pairs are of the type zypp(y2base)
in the
; Zypper snapshots are labeled
zypp(zypper)
.
Click
to open the list of files that differ between the two snapshots.Review the list of files. To display a “diff” between the pre- and post-version of a file, select it from the list.
To restore one or more files, select the relevant files or directories by activating the respective check box. Click
and confirm the action by clicking .To restore a single file, activate its diff view by clicking its name. Click
and confirm your choice with .snapper
Command #
Get a list of YaST and Zypper snapshots by running snapper
list -t pre-post
. YaST snapshots are labeled
as yast MODULE_NAME
in the
; Zypper snapshots are labeled
zypp(zypper)
.
tux >
sudo
snapper list -t pre-post Pre # | Post # | Pre Date | Post Date | Description ------+--------+-------------------------------+-------------------------------+-------------- 311 | 312 | Tue 06 May 2018 14:05:46 CEST | Tue 06 May 2018 14:05:52 CEST | zypp(y2base) 340 | 341 | Wed 07 May 2018 16:15:10 CEST | Wed 07 May 2018 16:15:16 CEST | zypp(zypper) 342 | 343 | Wed 07 May 2018 16:20:38 CEST | Wed 07 May 2018 16:20:42 CEST | zypp(y2base) 344 | 345 | Wed 07 May 2018 16:21:23 CEST | Wed 07 May 2018 16:21:24 CEST | zypp(zypper) 346 | 347 | Wed 07 May 2018 16:41:06 CEST | Wed 07 May 2018 16:41:10 CEST | zypp(y2base) 348 | 349 | Wed 07 May 2018 16:44:50 CEST | Wed 07 May 2018 16:44:53 CEST | zypp(y2base) 350 | 351 | Wed 07 May 2018 16:46:27 CEST | Wed 07 May 2018 16:46:38 CEST | zypp(y2base)
Get a list of changed files for a snapshot pair with snapper
status
PRE..POST. Files
with content changes are marked with , files that
have been added are marked with and deleted files
are marked with .
tux >
sudo
snapper status 350..351 +..... /usr/share/doc/packages/mikachan-fonts +..... /usr/share/doc/packages/mikachan-fonts/COPYING +..... /usr/share/doc/packages/mikachan-fonts/dl.html c..... /usr/share/fonts/truetype/fonts.dir c..... /usr/share/fonts/truetype/fonts.scale +..... /usr/share/fonts/truetype/みかちゃん-p.ttf +..... /usr/share/fonts/truetype/みかちゃん-pb.ttf +..... /usr/share/fonts/truetype/みかちゃん-ps.ttf +..... /usr/share/fonts/truetype/みかちゃん.ttf c..... /var/cache/fontconfig/7ef2298fde41cc6eeb7af42e48b7d293-x86_64.cache-4 c..... /var/lib/rpm/Basenames c..... /var/lib/rpm/Dirnames c..... /var/lib/rpm/Group c..... /var/lib/rpm/Installtid c..... /var/lib/rpm/Name c..... /var/lib/rpm/Packages c..... /var/lib/rpm/Providename c..... /var/lib/rpm/Requirename c..... /var/lib/rpm/Sha1header c..... /var/lib/rpm/Sigmd5
To display the diff for a certain file, run snapper
diff
PRE..POST
FILENAME. If you do not specify
FILENAME, a diff for all files will be
displayed.
tux >
sudo
snapper diff 350..351 /usr/share/fonts/truetype/fonts.scale --- /.snapshots/350/snapshot/usr/share/fonts/truetype/fonts.scale 2014-04-23 15:58:57.000000000 +0200 +++ /.snapshots/351/snapshot/usr/share/fonts/truetype/fonts.scale 2014-05-07 16:46:31.000000000 +0200 @@ -1,4 +1,4 @@ -1174 +1486 ds=y:ai=0.2:luximr.ttf -b&h-luxi mono-bold-i-normal--0-0-0-0-c-0-iso10646-1 ds=y:ai=0.2:luximr.ttf -b&h-luxi mono-bold-i-normal--0-0-0-0-c-0-iso8859-1 [...]
To restore one or more files run snapper -v undochange
PRE..POST
FILENAMES. If you do not specify a
FILENAMES, all changed files will be restored.
tux >
sudo
snapper -v undochange 350..351 create:0 modify:13 delete:7 undoing change... deleting /usr/share/doc/packages/mikachan-fonts deleting /usr/share/doc/packages/mikachan-fonts/COPYING deleting /usr/share/doc/packages/mikachan-fonts/dl.html deleting /usr/share/fonts/truetype/みかちゃん-p.ttf deleting /usr/share/fonts/truetype/みかちゃん-pb.ttf deleting /usr/share/fonts/truetype/みかちゃん-ps.ttf deleting /usr/share/fonts/truetype/みかちゃん.ttf modifying /usr/share/fonts/truetype/fonts.dir modifying /usr/share/fonts/truetype/fonts.scale modifying /var/cache/fontconfig/7ef2298fde41cc6eeb7af42e48b7d293-x86_64.cache-4 modifying /var/lib/rpm/Basenames modifying /var/lib/rpm/Dirnames modifying /var/lib/rpm/Group modifying /var/lib/rpm/Installtid modifying /var/lib/rpm/Name modifying /var/lib/rpm/Packages modifying /var/lib/rpm/Providename modifying /var/lib/rpm/Requirename modifying /var/lib/rpm/Sha1header modifying /var/lib/rpm/Sigmd5 undoing change done
Reverting user additions via undoing changes with Snapper is not recommended. Since certain directories are excluded from snapshots, files belonging to these users will remain in the file system. If a user with the same user ID as a deleted user is created, this user will inherit the files. Therefore it is strongly recommended to use the YaST
tool to remove users.Apart from the installation and administration snapshots, Snapper creates timeline snapshots. You can use these backup snapshots to restore files that have accidentally been deleted or to restore a previous version of a file. By using Snapper's diff feature you can also find out which modifications have been made at a certain point of time.
Being able to restore files is especially interesting for data, which may
reside on subvolumes or partitions for which snapshots are not taken by
default. To be able to restore files from home directories, for example,
create a separate Snapper configuration for /home
doing automatic timeline snapshots. See
Section 3.5, “Creating and Modifying Snapper Configurations” for instructions.
Snapshots taken from the root file system (defined by Snapper's root configuration), can be used to do a system rollback. The recommended way to do such a rollback is to boot from the snapshot and then perform the rollback. See Section 3.3, “System Rollback by Booting from Snapshots” for details.
Performing a rollback would also be possible by restoring all files from a
root file system snapshot as described below. However, this is not
recommended. You may restore single files, for example a configuration
file from the /etc
directory, but not the
complete list of files from the snapshot.
This restriction only affects snapshots taken from the root file system!
Start the yast2 snapper
.
Choose the
from which to choose a snapshot.Select a timeline snapshot from which to restore a file and choose
. Timeline snapshots are of the type with a description value of .Select a file from the text box by clicking the file name. The difference between the snapshot version and the current system is shown. Activate the check box to select the file for restore. Do so for all files you want to restore.
Click
and confirm the action by clicking .snapper
Command #Get a list of timeline snapshots for a specific configuration by running the following command:
tux >
sudo
snapper -c CONFIG list -t single | grep timeline
CONFIG needs to be replaced by an existing
Snapper configuration. Use snapper list-configs
to
display a list.
Get a list of changed files for a given snapshot by running the following command:
tux >
sudo
snapper -c CONFIG status SNAPSHOT_ID..0
Replace SNAPSHOT_ID by the ID for the snapshot from which you want to restore the file(s).
Optionally list the differences between the current file version and the one from the snapshot by running
tux >
sudo
snapper -c CONFIG diff SNAPSHOT_ID..0 FILE NAME
If you do not specify <FILE NAME>, the difference for all files are shown.
To restore one or more files, run
tux >
sudo
snapper -c CONFIG -v undochange SNAPSHOT_ID..0 FILENAME1 FILENAME2
If you do not specify file names, all changed files will be restored.
The GRUB 2 version included on openSUSE Leap can boot from Btrfs snapshots.
Together with Snapper's rollback feature, this allows to recover a
misconfigured system. Only snapshots created for the default Snapper
configuration (root
) are bootable.
As of openSUSE Leap 15.2 system rollbacks are only supported if the default subvolume configuration of the root partition has not been changed.
When booting a snapshot, the parts of the file system included in the snapshot are mounted read-only; all other file systems and parts that are excluded from snapshots are mounted read-write and can be modified.
When working with snapshots to restore data, it is important to know that there are two fundamentally different scenarios Snapper can handle:
When undoing changes as described in Section 3.2, “Using Snapper to Undo Changes”, two snapshots are compared and the changes between these two snapshots are reverted. Using this method also allows to explicitly exclude selected files from being restored.
When doing rollbacks as described in the following, the system is reset to the state at which the snapshot was taken.
To do a rollback from a bootable snapshot, the following requirements must be met. When doing a default installation, the system is set up accordingly.
The root file system needs to be Btrfs. Booting from LVM volume snapshots is not supported.
The root file system needs to be on a single device, a single partition
and a single subvolume. Directories that are excluded from snapshots such
as /srv
(see Section 3.1.3, “Directories That Are Excluded from Snapshots”
for a full list) may reside on separate partitions.
The system needs to be bootable via the installed boot loader.
To perform a rollback from a bootable snapshot, do as follows:
Boot the system. In the boot menu choose
and select the snapshot you want to boot. The list of snapshots is listed by date—the most recent snapshot is listed first.Log in to the system. Carefully check whether everything works as expected. Note that you cannot write to any directory that is part of the snapshot. Data you write to other directories will not get lost, regardless of what you do next.
Depending on whether you want to perform the rollback or not, choose your next step:
If the system is in a state where you do not want to do a rollback, reboot to boot into the current system state. You can then choose a different snapshot, or start the rescue system.
To perform the rollback, run
tux >
sudo
snapper rollback
and reboot afterward. On the boot screen, choose the default boot entry to reboot into the reinstated system. A snapshot of the file system status before the rollback is created. The default subvolume for root will be replaced with a fresh read-write snapshot. For details, see Section 3.3.1, “Snapshots after Rollback”.
It is useful to add a description for the snapshot with the -d
option.
For example:
New file system root since rollback on DATE TIME
If snapshots are not disabled during installation, an initial bootable
snapshot is created at the end of the initial system installation. You can
go back to that state at any time by booting this snapshot. The snapshot
can be identified by the description after installation
.
A bootable snapshot is also created when starting a system upgrade to a service pack or a new major release (provided snapshots are not disabled).
Before a rollback is performed, a snapshot of the running file system is created. The description references the ID of the snapshot that was restored in the rollback.
Snapshots created by rollbacks receive the value number
for the Cleanup
attribute. The rollback snapshots are
therefore automatically deleted when the set number of snapshots is reached.
Refer to Section 3.7, “Automatic Snapshot Clean-Up” for details.
If the snapshot contains important data, extract the data from the snapshot
before it is removed.
For example, after a fresh installation the following snapshots are available on the system:
root #
snapper
--iso list Type | # | | Cleanup | Description | Userdata -------+---+ ... +---------+-----------------------+-------------- single | 0 | | | current | single | 1 | | | first root filesystem | single | 2 | | number | after installation | important=yes
After running sudo snapper rollback
snapshot
3
is created and contains the state of the system
before the rollback was executed. Snapshot 4
is
the new default Btrfs subvolume and thus the system after a reboot.
root #
snapper
--iso list Type | # | | Cleanup | Description | Userdata -------+---+ ... +---------+-----------------------+-------------- single | 0 | | | current | single | 1 | | number | first root filesystem | single | 2 | | number | after installation | important=yes single | 3 | | number | rollback backup of #1 | important=yes single | 4 | | | |
To boot from a snapshot, reboot your machine and choose ↓ and ↑ to navigate and press Enter to activate the selected snapshot. Activating a snapshot from the boot menu does not reboot the machine immediately, but rather opens the boot loader of the selected snapshot.
. A screen listing all bootable snapshots opens. The most recent snapshot is listed first, the oldest last. Use the keysEach snapshot entry in the boot loader follows a naming scheme which makes it possible to identify it easily:
[*]1OS2 (KERNEL3,DATE4TTIME5,DESCRIPTION6)
If the snapshot was marked | |
Operating system label. | |
Date in the format | |
Time in the format | |
This field contains a description of the snapshot. In case of a manually
created snapshot this is the string created with the option
|
It is possible to replace the default string in the description field of a snapshot with a custom string. This is for example useful if an automatically created description is not sufficient, or a user-provided description is too long. To set a custom string STRING for snapshot NUMBER, use the following command:
tux >
sudo
snapper modify --userdata "bootloader=STRING" NUMBER
The description should be no longer than 25 characters—everything that exceeds this size will not be readable on the boot screen.
A complete system rollback, restoring the complete system to the identical state as it was in when a snapshot was taken, is not possible.
Root file system snapshots do not contain all directories. See Section 3.1.3, “Directories That Are Excluded from Snapshots” for details and reasons. As a general consequence, data from these directories is not restored, resulting in the following limitations.
Applications and add-ons installing data in subvolumes excluded from
the snapshot, such as /opt
, may not work after a
rollback, if others parts of the application data are also installed on
subvolumes included in the snapshot. Re-install the application or the
add-on to solve this problem.
If an application had changed file permissions and/or ownership in between snapshot and current system, the application may not be able to access these files. Reset permissions and/or ownership for the affected files after the rollback.
If a service or an application has established a new data format in between snapshot and current system, the application may not be able to read the affected data files after a rollback.
Subvolumes like /srv
may contain a mixture of code
and data. A rollback may result in non-functional code. A downgrade of
the PHP version, for example, may result in broken PHP scripts for the
Web server.
If a rollback removes users from the system, data that is owned by
these users in directories excluded from the snapshot, is not removed.
If a user with the same user ID is created, this user will inherit the
files. Use a tool like find
to locate and remove
orphaned files.
A rollback of the boot loader is not possible, since all
“stages” of the boot loader must fit together. This cannot be
guaranteed when doing rollbacks of /boot
.
You may enable snapshots for users' /home
directories, which supports a number of use cases:
Individual users may manage their own snapshots and rollbacks.
System users, for example database, system, and network admins who want to track copies of configuration files, documentation, and so on.
Samba shares with home directories and Btrfs back-end.
Each user's directory is a Btrfs subvolume of /home
.
It is possible to set this up manually
(see Section 3.4.3, “Manually Enabling Snapshots in Home Directories”). However, a
more convenient way is to use pam_snapper
.
The pam_snapper
package installs the
pam_snapper.so
module and helper scripts, which
automate user creation and Snapper configuration.
pam_snapper
provides integration with the
useradd
command, pluggable
authentication modules (PAM), and Snapper. By default it creates snapshots
at user login and logout, and also creates time-based snapshots as some
users remain logged in for extended periods of time. You may change the
defaults using the normal Snapper commands and configuration files.
The easiest way is to start with a new /home
directory formatted with Btrfs, and no existing users. Install
pam_snapper
:
root #
zypper in pam_snapper
Add this line to /etc/pam.d/common-session
:
session optional pam_snapper.so
Use the /usr/lib/pam_snapper/pam_snapper_useradd.sh
script to create a new user and home directory. By default the script
performs a dry run. Edit the script to change
DRYRUN=1
to DRYRUN=0
. Now you
can create a new user:
root #
/usr/lib/pam_snapper/pam_snapper_useradd.sh \
username group passwd=password
Create subvolume '/home/username'
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
The files from /etc/skel
will be copied
into the user's home directory at their first login. Verify that
the user's configuration was created by listing your Snapper
configurations:
root #
snapper list --all
Config: home_username, subvolume: /home/username
Type | # | Pre # | Date | User | Cleanup | Description | Userdata
-------+---+-------+------+------+---------+-------------+---------
single | 0 | | | root | | current |
Over time, this output will become populated with a list of snapshots, which the user can manage with the standard Snapper commands.
Remove users with the
/usr/lib/pam_snapper/pam_snapper_userdel.sh
script. By default it performs a dry run, so edit it to change
DRYRUN=1
to DRYRUN=0
. This
removes the user, the user's home subvolume, Snapper configuration,
and deletes all snapshots.
root #
/usr/lib/pam_snapper/pam_snapper_userdel.sh username
These are the steps for manually setting up users' home directories
with Snapper. /home
must be formatted with Btrfs,
and the users not yet created.
root #
btrfs subvol create /home/usernameroot #
snapper -c home_username create-config /home/usernameroot #
sed -i -e "s/ALLOW_USERS=\"\"/ALLOW_USERS=\"username\"/g" \ /etc/snapper/configs/home_usernameroot #
yast users add username=username home=/home/username password=passwordroot #
chown username.group /home/usernameroot #
chmod 755 /home/username/.snapshots
The way Snapper behaves is defined in a configuration file that is specific
for each partition or Btrfs
subvolume. These
configuration files reside under /etc/snapper/configs/
.
In case the root file system is big enough (approximately 12 GB), snapshots
are automatically enabled for the root file system /
upon installation. The corresponding default configuration is named
root
. It creates and manages the YaST and Zypper
snapshot. See Section 3.5.1.1, “Configuration Data” for a list
of the default values.
As explained in Section 3.1, “Default Setup”, enabling snapshots requires additional free space in the root file system. The amount depends on the amount of packages installed and the amount of changes made to the volume that is included in snapshots. The snapshot frequency and the number of snapshots that get archived also matter.
There is a minimum root file system size that is required to automatically
enable snapshots during the installation. Currently this size is
approximately 12 GB. This value may change in the future, depending on
architecture and the size of the base system. It depends on the values for
the following tags in the file /control.xml
from the
installation media:
<root_base_size> <btrfs_increase_percentage>
It is calculated with the following formula: ROOT_BASE_SIZE * (1 + BTRFS_INCREASE_PERCENTAGE/100)
Keep in mind that this value is a minimum size. Consider using more space for the root file system. As a rule of thumb, double the size you would use when not having enabled snapshots.
You may create your own configurations for other partitions formatted with
Btrfs
or existing subvolumes on a
Btrfs
partition. In the following example we will set up
a Snapper configuration for backing up the Web server data residing on a
separate, Btrfs
-formatted partition mounted at
/srv/www
.
After a configuration has been created, you can either use
snapper
itself or the YaST
module to restore files from these snapshots. In YaST you need to select
your , while you need to specify
your configuration for snapper
with the global switch
-c
(for example, snapper -c myconfig
list
).
To create a new Snapper configuration, run snapper
create-config
:
tux >
sudo
snapper -c www-data1 create-config /srv/www2
Name of configuration file. | |
Mount point of the partition or |
This command will create a new configuration file
/etc/snapper/configs/www-data
with reasonable default
values (taken from
/etc/snapper/config-templates/default
). Refer to
Section 3.5.1, “Managing Existing Configurations” for instructions on how to
adjust these defaults.
Default values for a new configuration are taken from
/etc/snapper/config-templates/default
. To use your own
set of defaults, create a copy of this file in the same directory and
adjust it to your needs. To use it, specify the -t
option
with the create-config command:
tux >
sudo
snapper -c www-data create-config -t MY_DEFAULTS /srv/www
The snapper
command offers several subcommands for managing
existing configurations. You can list, show, delete and modify them:
Use the subcommand snapper list-configs
to get all
existing configurations:
tux >
sudo
snapper list-configs Config | Subvolume -------+---------- root | / usr | /usr local | /local
Use the subcommand snapper -c
CONFIG get-config
to display the
specified configuration. Replace CONFIG with
one of the configuration names shown by
snapper list-configs
.
For more information about the configuration options, see
Section 3.5.1.1, “Configuration Data”.
To display the default configuration, run:
tux >
sudo
snapper -c root get-config
Use the subcommand snapper -c CONFIG
set-config
OPTION=VALUE
to modify an option in the specified configuration.
Replace CONFIG with one of the
configuration names shown by snapper list-configs
.
Possible values for OPTION and
VALUE are listed in Section 3.5.1.1, “Configuration Data”.
Use the subcommand snapper -c
CONFIG delete-config
to delete a
configuration. Replace CONFIG with one of the
configuration names shown by snapper list-configs
.
Each configuration contains a list of options that can be modified from
the command line. The following list provides details for each option. To
change a value, run snapper -c CONFIG
set-config
"KEY=VALUE"
.
ALLOW_GROUPS
,
ALLOW_USERS
Granting permissions to use snapshots to regular users. See Section 3.5.1.2, “Using Snapper as Regular User” for more information.
The default value is ""
.
BACKGROUND_COMPARISON
Defines whether pre and post snapshots should be compared in the background after creation.
The default value is "yes"
.
EMPTY_*
Defines the clean-up algorithm for snapshots pairs with identical pre and post snapshots. See Section 3.7.3, “Cleaning Up Snapshot Pairs That Do Not Differ” for details.
FSTYPE
File system type of the partition. Do not change.
The default value is "btrfs"
.
NUMBER_*
Defines the clean-up algorithm for installation and admin snapshots. See Section 3.7.1, “Cleaning Up Numbered Snapshots” for details.
QGROUP
/ SPACE_LIMIT
Adds quota support to the clean-up algorithms. See Section 3.7.5, “Adding Disk Quota Support” for details.
SUBVOLUME
Mount point of the partition or subvolume to snapshot. Do not change.
The default value is "/"
.
SYNC_ACL
If Snapper is used by regular users (see
Section 3.5.1.2, “Using Snapper as Regular User”), the users must be able to
access the .snapshot
directories and to read files
within them. If SYNC_ACL is set to yes
, Snapper
automatically makes them accessible using ACLs for users and groups
from the ALLOW_USERS or ALLOW_GROUPS entries.
The default value is "no"
.
TIMELINE_CREATE
If set to yes
, hourly snapshots are created. Valid
values: yes
, no
.
The default value is "no"
.
TIMELINE_CLEANUP
/
TIMELINE_LIMIT_*
Defines the clean-up algorithm for timeline snapshots. See Section 3.7.2, “Cleaning Up Timeline Snapshots” for details.
By default Snapper can only be used by root
. However, there are
cases in which certain groups or users need to be able to create snapshots
or undo changes by reverting to a snapshot:
Web site administrators who want to take snapshots of
/srv/www
Users who want to take a snapshot of their home directory
For these purposes, you can create Snapper configurations that grant
permissions to users or/and groups. The corresponding
.snapshots
directory needs to be readable and
accessible by the specified users. The easiest way to achieve this is to
set the SYNC_ACL option to yes
.
Note that all steps in this procedure need to be run by root
.
If a Snapper configuration does not exist yet, create one for the partition or subvolume on which the user should be able to use Snapper. Refer to Section 3.5, “Creating and Modifying Snapper Configurations” for instructions. Example:
tux >
sudo
snapper --config web_data create /srv/www
The configuration file is created under
/etc/snapper/configs/CONFIG
,
where CONFIG is the value you specified with
-c/--config
in the previous step (for example
/etc/snapper/configs/web_data
). Adjust it according
to your needs. For more information, see
Section 3.5.1, “Managing Existing Configurations”.
Set values for ALLOW_USERS
and/or
ALLOW_GROUPS
to grant permissions to users and/or groups,
respectively. Multiple entries need to be separated by
Space. To grant permissions to the user
www_admin
for example, run:
tux >
sudo
snapper -c web_data set-config "ALLOW_USERS=www_admin" SYNC_ACL="yes"
The given Snapper configuration can now be used by the specified user(s)
and/or group(s). You can test it with the list
command, for example:
www_admin:~ >
snapper -c web_data list
Snapper is not restricted to creating and managing snapshots automatically by configuration; you can also create snapshot pairs (“before and after”) or single snapshots manually using either the command-line tool or the YaST module.
All Snapper operations are carried out for an existing configuration (see
Section 3.5, “Creating and Modifying Snapper Configurations” for details). You can only take
snapshots of partitions or volumes for which a configuration exists. By
default the system configuration (root
) is used.
To create or manage snapshots for your own configuration you need to
explicitly choose it. Use the
drop-down box in YaST or specify the -c
on the command
line (snapper -c MYCONFIG
COMMAND
).
Each snapshot consists of the snapshot itself and some metadata. When
creating a snapshot you also need to specify the metadata. Modifying a
snapshot means changing its metadata—you cannot modify its content.
Use snapper list
to show existing snapshots and their
metadata:
snapper --config home list
Lists snapshots for the configuration home
. To list
snapshots for the default configuration (root), use snapper -c
root list
or snapper list
.
snapper list -a
Lists snapshots for all existing configurations.
snapper list -t pre-post
Lists all pre and post snapshot pairs for the default
(root
) configuration.
snapper list -t single
Lists all snapshots of the type single
for the
default (root
) configuration.
The following metadata is available for each snapshot:
Type: Snapshot type, see Section 3.6.1.1, “Snapshot Types” for details. This data cannot be changed.
Number: Unique number of the snapshot. This data cannot be changed.
Pre Number: Specifies the number of the corresponding pre snapshot. For snapshots of type post only. This data cannot be changed.
Description: A description of the snapshot.
Userdata: An extended description where
you can specify custom data in the form of a comma-separated key=value
list: reason=testing, project=foo
. This field is also
used to mark a snapshot as important (important=yes
)
and to list the user that created the snapshot
(user=tux).
Cleanup-Algorithm: Cleanup-algorithm for the snapshot, see Section 3.7, “Automatic Snapshot Clean-Up” for details.
Snapper knows three different types of snapshots: pre, post, and single. Physically they do not differ, but Snapper handles them differently.
pre
Snapshot of a file system before a modification.
Each pre
snapshot corresponds to a
post
snapshot.
For example, this is used for the automatic YaST/Zypper snapshots.
post
Snapshot of a file system after a modification.
Each post
snapshot corresponds to a
pre
snapshot.
For example, this is used for the automatic YaST/Zypper snapshots.
single
Stand-alone snapshot. For example, this is used for the automatic hourly snapshots. This is the default type when creating snapshots.
Snapper provides three algorithms to clean up old snapshots. The
algorithms are executed in a daily
cron
job.
It is possible to define the
number of different types of snapshots to keep in the Snapper
configuration (see Section 3.5.1, “Managing Existing Configurations” for
details).
Deletes old snapshots when a certain snapshot count is reached.
Deletes old snapshots having passed a certain age, but keeps several hourly, daily, monthly, and yearly snapshots.
Deletes pre/post snapshot pairs with empty diffs.
To create a snapshot, run snapper create
or
click in the YaST module
. The following examples explain how to create
snapshots from the command line.
The YaST interface for Snapper is not explicitly described here but
provides equivalent functionality.
Always specify a meaningful description to later be able to
identify its purpose. You can also specify additional information via
the option --userdata
.
snapper create --from 17 --description
"with package2"
Creates a stand-alone snapshot (type single) from an existing snapshot, which is specified
by the snapshot's number from snapper list
. (This applies to Snapper version
0.8.4 and newer.)
snapper create --description "Snapshot for week 2
2014"
Creates a stand-alone snapshot (type single) for the default
(root
) configuration with a description. Because no
cleanup-algorithm is specified, the snapshot will never be deleted
automatically.
snapper --config home create --description "Cleanup in
~tux"
Creates a stand-alone snapshot (type single) for a custom configuration
named home
with a description. Because no
cleanup-algorithm is specified, the snapshot will never be deleted
automatically.
snapper --config home create --description "Daily data
backup" --cleanup-algorithm timeline
>
Creates a stand-alone snapshot (type single) for a custom configuration
named home
with a description. The snapshot will
automatically be deleted when it meets the criteria specified for the
timeline cleanup-algorithm in the configuration.
snapper create --type pre --print-number --description
"Before the Apache config cleanup" --userdata "important=yes"
Creates a snapshot of the type pre
and prints the
snapshot number. First command needed to create a pair of snapshots used
to save a “before” and “after” state. The
snapshot is marked as important.
snapper create --type post --pre-number 30 --description
"After the Apache config cleanup" --userdata "important=yes"
Creates a snapshot of the type post
paired with the
pre
snapshot number 30
. Second
command needed to create a pair of snapshots used to save a
“before” and “after” state. The snapshot is
marked as important.
snapper create --command COMMAND
--description "Before and after COMMAND"
Automatically creates a snapshot pair before and after running COMMAND. This option is only available when using snapper on the command line.
Snapper allows you to modify the description, the cleanup algorithm, and the user data of a snapshot. All other metadata cannot be changed. The following examples explain how to modify snapshots from the command line. It should be easy to adopt them when using the YaST interface.
To modify a snapshot on the command line, you need to know its number. Use
snapper list
to display all snapshots
and their numbers.
The YaST
module already lists all snapshots. Choose one from the list and click .snapper modify --cleanup-algorithm "timeline"
10
Modifies the metadata of snapshot 10 for the default
(root
) configuration. The cleanup algorithm is set to
timeline
.
snapper --config home modify --description "daily backup"
-cleanup-algorithm "timeline" 120
Modifies the metadata of snapshot 120 for a custom configuration named
home
. A new description is set and the cleanup
algorithm is unset.
To delete a snapshot with the YaST
module, choose a snapshot from the list and click .
To delete a snapshot with the command-line tool, you need to know its
number. Get it by running snapper list
. To delete a
snapshot, run snapper delete
NUMBER.
Deleting the current default subvolume snapshot is not allowed.
When deleting snapshots with Snapper, the freed space will be claimed by a
Btrfs process running in the background. Thus the visibility and the
availability of free space is delayed. In case you need space freed by
deleting a snapshot to be available immediately, use the option
--sync
with the delete command.
When deleting a pre
snapshot, you should always delete
its corresponding post
snapshot (and vice versa).
snapper delete 65
Deletes snapshot 65 for the default (root
)
configuration.
snapper -c home delete 89 90
Deletes snapshots 89 and 90 for a custom configuration named
home
.
snapper delete --sync 23
Deletes snapshot 23 for the default (root
)
configuration and makes the freed space available immediately.
Sometimes the Btrfs snapshot is present but the XML file containing the metadata for Snapper is missing. In this case the snapshot is not visible for Snapper and needs to be deleted manually:
btrfs subvolume delete /.snapshots/SNAPSHOTNUMBER/snapshot rm -rf /.snapshots/SNAPSHOTNUMBER
If you delete snapshots to free space on your hard disk, make sure to delete old snapshots first. The older a snapshot is, the more disk space it occupies.
Snapshots are also automatically deleted by a daily cron job. Refer to Section 3.6.1.2, “Cleanup Algorithms” for details.
Snapshots occupy disk space and over time the amount of disk space occupied by the snapshots may become large. To prevent disks from running out of space, Snapper offers algorithms to automatically delete old snapshots. These algorithms differentiate between timeline snapshots and numbered snapshots (administration plus installation snapshot pairs). You can specify the number of snapshots to keep for each type.
In addition to that, you can optionally specify a disk space quota, defining the maximum amount of disk space the snapshots may occupy. It is also possible to automatically delete pre and post snapshots pairs that do not differ.
A clean-up algorithm is always bound to a single Snapper configuration, so you need to configure algorithms for each configuration. To prevent certain snapshots from being automatically deleted, refer to Can a snapshot be protected from deletion? .
The default setup (root
) is configured to do clean-up
for numbered snapshots and empty pre and post snapshot pairs. Quota support
is enabled—snapshots may not occupy more than 50% of the available
disk space of the root partition. Timeline snapshots are disabled by
default, therefore the timeline clean-up algorithm is also disabled.
Cleaning up numbered snapshots—administration plus installation snapshot pairs—is controlled by the following parameters of a Snapper configuration.
NUMBER_CLEANUP
Enables or disables clean-up of installation and admin snapshot pairs.
If enabled, snapshot pairs are deleted when the total snapshot count
exceeds a number specified with NUMBER_LIMIT
and/or
NUMBER_LIMIT_IMPORTANT
and an
age specified with NUMBER_MIN_AGE
. Valid values:
yes
(enable), no
(disable).
The default value is "yes"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_CLEANUP=no"
NUMBER_LIMIT
/
NUMBER_LIMIT_IMPORTANT
Defines how many regular and/or important installation and
administration snapshot pairs to keep. Ignored if
NUMBER_CLEANUP
is set to
"no"
.
The default value is "2-10"
for
NUMBER_LIMIT
and "4-10"
for NUMBER_LIMIT_IMPORTANT
. The cleaning
algorithms delete snapshots above the specified maximum value,
without taking the snapshot and filesystem space into
account. The algorithms also delete snapshots above the minimum
value until the limits for the snapshot and filesystem are
reached.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_LIMIT=10"
In case quota support is enabled (see
Section 3.7.5, “Adding Disk Quota Support”) the limit needs
to be specified as a minimum-maximum range, for example
2-10
. If quota support is disabled, a constant
value, for example 10
, needs to be provided,
otherwise cleaning-up will fail with an error.
NUMBER_MIN_AGE
Defines the minimum age in seconds a snapshot must have before it can automatically be deleted. Snapshots younger than the value specified here will not be deleted, regardless of how many exist.
The default value is "1800"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "NUMBER_MIN_AGE=864000"
NUMBER_LIMIT
, NUMBER_LIMIT_IMPORTANT
and NUMBER_MIN_AGE
are always evaluated. Snapshots are
only deleted when all conditions are met.
If you always want to keep the number of snapshots defined with
NUMBER_LIMIT*
regardless of their age, set
NUMBER_MIN_AGE
to 0
.
The following example shows a configuration to keep the last 10 important and regular snapshots regardless of age:
NUMBER_CLEANUP=yes NUMBER_LIMIT_IMPORTANT=10 NUMBER_LIMIT=10 NUMBER_MIN_AGE=0
On the other hand, if you do not want to keep snapshots beyond a certain
age, set NUMBER_LIMIT*
to 0
and
provide the age with NUMBER_MIN_AGE
.
The following example shows a configuration to only keep snapshots younger than ten days:
NUMBER_CLEANUP=yes NUMBER_LIMIT_IMPORTANT=0 NUMBER_LIMIT=0 NUMBER_MIN_AGE=864000
Cleaning up timeline snapshots is controlled by the following parameters of a Snapper configuration.
TIMELINE_CLEANUP
Enables or disables clean-up of timeline snapshots. If enabled,
snapshots are deleted when the total snapshot count exceeds a number
specified with TIMELINE_LIMIT_*
and an age specified with
TIMELINE_MIN_AGE
. Valid values:
yes
, no
.
The default value is "yes"
.
Example command to change or set:
tux >
sudo
snapper -c CONFIG set-config "TIMELINE_CLEANUP=yes"
TIMELINE_LIMIT_DAILY
,
TIMELINE_LIMIT_HOURLY
,
TIMELINE_LIMIT_MONTHLY
,
TIMELINE_LIMIT_WEEKLY
,
TIMELINE_LIMIT_YEARLY
Number of snapshots to keep for hour, day, month, week, and year.
The default value for each entry is "10"
, except for
TIMELINE_LIMIT_WEEKLY
, which is set to
"0"
by default.
TIMELINE_MIN_AGE
Defines the minimum age in seconds a snapshot must have before it can automatically be deleted.
The default value is "1800"
.
TIMELINE_CLEANUP="yes" TIMELINE_CREATE="yes" TIMELINE_LIMIT_DAILY="7" TIMELINE_LIMIT_HOURLY="24" TIMELINE_LIMIT_MONTHLY="12" TIMELINE_LIMIT_WEEKLY="4" TIMELINE_LIMIT_YEARLY="2" TIMELINE_MIN_AGE="1800"
This example configuration enables hourly snapshots which are
automatically cleaned up. TIMELINE_MIN_AGE
and
TIMELINE_LIMIT_*
are always both evaluated. In this
example, the minimum age of a snapshot before it can be deleted is set to
30 minutes (1800 seconds). Since we create hourly snapshots, this ensures
that only the latest snapshots are kept. If
TIMELINE_LIMIT_DAILY
is set to not zero, this means
that the first snapshot of the day is kept, too.
Hourly: The last 24 snapshots that have been made.
Daily: The first daily snapshot that has been made is kept from the last seven days.
Monthly: The first snapshot made on the last day of the month is kept for the last twelve months.
Weekly: The first snapshot made on the last day of the week is kept from the last four weeks.
Yearly: The first snapshot made on the last day of the year is kept for the last two years.
As explained in Section 3.1.2, “Types of Snapshots”, whenever you run a YaST module or execute Zypper, a pre snapshot is created on start-up and a post snapshot is created when exiting. In case you have not made any changes there will be no difference between the pre and post snapshots. Such “empty” snapshot pairs can be automatically be deleted by setting the following parameters in a Snapper configuration:
EMPTY_PRE_POST_CLEANUP
If set to yes
, pre and post snapshot pairs that do
not differ will be deleted.
The default value is "yes"
.
EMPTY_PRE_POST_MIN_AGE
Defines the minimum age in seconds a pre and post snapshot pair that does not differ must have before it can automatically be deleted.
The default value is "1800"
.
Snapper does not offer custom clean-up algorithms for manually created snapshots. However, you can assign the number or timeline clean-up algorithm to a manually created snapshot. If you do so, the snapshot will join the “clean-up queue” for the algorithm you specified. You can specify a clean-up algorithm when creating a snapshot, or by modifying an existing snapshot:
snapper create --description "Test" --cleanup-algorithm number
Creates a stand-alone snapshot (type single) for the default (root)
configuration and assigns the number
clean-up
algorithm.
snapper modify --cleanup-algorithm "timeline" 25
Modifies the snapshot with the number 25 and assigns the clean-up
algorithm timeline
.
In addition to the number and/or timeline clean-up algorithms described above, Snapper supports quotas. You can define what percentage of the available space snapshots are allowed to occupy. This percentage value always applies to the Btrfs subvolume defined in the respective Snapper configuration.
Btrfs quotas are applied to subvolumes, not to users. You may apply
disk space quotas to users and groups (for example, with the
quota
command) in addition to using Btrfs quotas.
If Snapper was enabled during the installation, quota support is
automatically enabled. In case you manually enable Snapper at a later point
in time, you can enable quota support by running snapper
setup-quota
. This requires a valid configuration (see
Section 3.5, “Creating and Modifying Snapper Configurations” for more information).
Quota support is controlled by the following parameters of a Snapper configuration.
QGROUP
The Btrfs quota group used by Snapper. If not set, run snapper
setup-quota
. If already set, only change if you are familiar
with man 8 btrfs-qgroup
. This value is set with
snapper setup-quota
and should not be changed.
SPACE_LIMIT
Limit of space snapshots are allowed to use in fractions of 1 (100%). Valid values range from 0 to 1 (0.1 = 10%, 0.2 = 20%, ...).
The following limitations and guidelines apply:
Quotas are only activated in addition to an existing number and/or timeline clean-up algorithm. If no clean-up algorithm is active, quota restrictions are not applied.
With quota support enabled, Snapper will perform two clean-up runs if required. The first run will apply the rules specified for number and timeline snapshots. Only if the quota is exceeded after this run, the quota-specific rules will be applied in a second run.
Even if quota support is enabled, Snapper will always keep the number of
snapshots specified with the NUMBER_LIMIT*
and
TIMELINE_LIMIT*
values, even if the quota will be
exceeded. It is therefore recommended to specify ranged values
(MIN-MAX
)
for NUMBER_LIMIT*
and
TIMELINE_LIMIT*
to ensure the quota can be applied.
If, for example, NUMBER_LIMIT=5-20
is set, Snapper
will perform a first clean-up run and reduce the number of regular
numbered snapshots to 20. In case these 20 snapshots exceed the
quota, Snapper will delete the oldest ones in a second run until the
quota is met. A minimum of five snapshots will always be kept, regardless
of the amount of space they occupy.
Snapshots share data, for efficient use of storage space, so using ordinary
commands like du
and df
won't measure
used disk space accurately. When you want to free up disk space on Btrfs
with quotas enabled, you need to know how much exclusive disk space is
used by each snapshot, rather than shared space. Snapper 0.6 and up reports
the used disk space for each snapshot in the
Used Space
column:
root #
snapper--iso list
# | Type | Pre # | Date | User | Used Space | Cleanup | Description | Userdata
----+--------+-------+---------------------+------+------------+---------+-----------------------+--------------
0 | single | | | root | | | current |
1* | single | | 2019-07-22 13:08:38 | root | 16.00 KiB | | first root filesystem |
2 | single | | 2019-07-22 14:21:05 | root | 14.23 MiB | number | after installation | important=yes
3 | pre | | 2019-07-22 14:26:03 | root | 144.00 KiB | number | zypp(zypper) | important=no
4 | post | 3 | 2019-07-22 14:26:04 | root | 112.00 KiB | number | | important=no
5 | pre | | 2019-07-23 08:19:36 | root | 128.00 KiB | number | zypp(zypper) | important=no
6 | post | 5 | 2019-07-23 08:19:43 | root | 80.00 KiB | number | | important=no
7 | pre | | 2019-07-23 08:20:50 | root | 256.00 KiB | number | yast sw_single |
8 | pre | | 2019-07-23 08:23:22 | root | 112.00 KiB | number | zypp(ruby.ruby2.5) | important=no
9 | post | 8 | 2019-07-23 08:23:35 | root | 64.00 KiB | number | | important=no
10 | post | 7 | 2019-07-23 08:24:05 | root | 16.00 KiB | number | |
The btrfs
command provides another view of space used by
snapshots:
root #
btrfs qgroup show -p /
qgroupid rfer excl parent
-------- ---- ---- ------
0/5 16.00KiB 16.00KiB ---
[...]
0/272 3.09GiB 14.23MiB 1/0
0/273 3.11GiB 144.00KiB 1/0
0/274 3.11GiB 112.00KiB 1/0
0/275 3.11GiB 128.00KiB 1/0
0/276 3.11GiB 80.00KiB 1/0
0/277 3.11GiB 256.00KiB 1/0
0/278 3.11GiB 112.00KiB 1/0
0/279 3.12GiB 64.00KiB 1/0
0/280 3.12GiB 16.00KiB 1/0
1/0 3.33GiB 222.95MiB ---
The qgroupid
column displays the identification number for
each subvolume, assigning a qgroup level/ID combination.
The rfer
column displays the total amount of data
referred to in the subvolume.
The excl
column displays the exclusive data in each
subvolume.
The parent
column shows the parent qgroup of the subvolumes.
The final item, 1/0
, shows the totals for the parent
qgroup. In the above example, 222.95 MiB will be freed if all subvolumes
are removed. Run the following command to see which snapshots are associated
with each subvolume:
root #
btrfs subvolume list -st /
ID gen top level path
-- --- --------- ----
267 298 266 @/.snapshots/1/snapshot
272 159 266 @/.snapshots/2/snapshot
273 170 266 @/.snapshots/3/snapshot
274 171 266 @/.snapshots/4/snapshot
275 287 266 @/.snapshots/5/snapshot
276 288 266 @/.snapshots/6/snapshot
277 292 266 @/.snapshots/7/snapshot
278 296 266 @/.snapshots/8/snapshot
279 297 266 @/.snapshots/9/snapshot
280 298 266 @/.snapshots/10/snapshot
Doing an upgrade from one service pack to another results in snapshots occupying a lot of disk space on the system subvolumes. Manually deleting these snapshots after they are no longer needed is recommended. See Section 3.6.4, “Deleting Snapshots” for details.
/var/log
,
/tmp
and other directories?
For some directories we decided to exclude them from snapshots. See Section 3.1.3, “Directories That Are Excluded from Snapshots” for a list and reasons. To exclude a path from snapshots we create a subvolume for that path.
Yes—refer to Section 3.3, “System Rollback by Booting from Snapshots” for details.
Currently Snapper does not offer means to prevent a snapshot from being
deleted manually. However, you can prevent snapshots from being
automatically deleted by clean-up algorithms. Manually created snapshots
(see Section 3.6.2, “Creating Snapshots”) have no clean-up
algorithm assigned unless you specify one with
--cleanup-algorithm
. Automatically created snapshots
always either have the number
or
timeline
algorithm assigned. To remove such an
assignment from one or more snapshots, proceed as follows:
List all available snapshots:
tux >
sudo
snapper list -a
Memorize the number of the snapshot(s) you want to prevent from being deleted.
Run the following command and replace the number placeholders with the number(s) you memorized:
tux >
sudo
snapper modify --cleanup-algorithm "" #1 #2 #n
Check the result by running snapper list -a
again.
The entry in the column Cleanup
should now be empty
for the snapshots you modified.
See the Snapper home page at http://snapper.io/.
Virtual Network Computing (VNC) enables you to access a remote computer via a graphical desktop, and run remote graphical applications. VNC is platform-independent and accesses the remote machine from any operating system. This chapter describes how to connect to a VNC server with the desktop clients vncviewer and Remmina, and how to operate a VNC server.
openSUSE Leap supports two different kinds of VNC sessions: One-time sessions that “live” as long as the VNC connection from the client is kept up, and persistent sessions that “live” until they are explicitly terminated.
A VNC server can offer both kinds of sessions simultaneously on different ports, but an open session cannot be converted from one type to the other.
vncviewer
Client #Edit source
A machine can reliably accept VNC connections only if it uses a display
manager that supports the XDMCP protocol. While
gdm
, lxdm
, or
lightdm
support XDMCP, the KDE 5 default display
manager sddm
does not support it. When changing the
default display manager, remember to log out of the current X session and
restart the display manager with
tux >
sudo systemctl restart xdm.service
To connect to a VNC service provided by a server, a client is needed. The
default in openSUSE Leap is vncviewer
, provided by the
tigervnc
package.
To start your VNC viewer and initiate a session with the server, use the command:
tux >
vncviewer jupiter.example.com:1
Instead of the VNC display number you can also specify the port number with two colons:
tux >
vncviewer jupiter.example.com::5901
The actual display or port number you specify in the VNC client must be
the same as the display or port number picked by the
vncserver
command on the target machine. See
Section 4.4, “Configuring Persistent VNC Server Sessions” for further info.
By running vncviewer
without specifying
--listen
or a host to connect to, it will show a window
to ask for connection details. Enter the host into the field like in Section 4.1.1, “Connecting Using the vncviewer CLI”
and click .
The VNC protocol supports different kinds of encrypted connections, not to be confused with password authentication. If a connection does not use TLS, the text “(Connection not encrypted!)” can be seen in the window title of the VNC viewer.
Remmina is a modern and feature rich remote desktop client. It supports several access methods, for example VNC, SSH, RDP, and Spice.
To use Remmina, verify whether the remmina package is installed on your system, and install it if not. Remember to install the VNC plug-in for Remmina as well:
root #
zypper in remmina remmina-plugin-vnc
Run Remmina by entering the remmina
command.
The main application window shows the list of stored remote sessions. Here you can add and save a new remote session, quick-start a new session without saving it, start a previously saved session, or set Remmina's global preferences.
To add and save a new remote session, click in the top left of the main window. The
window opens.Complete the fields that specify your newly added remote session profile. The most important are:
Name of the profile. It will be listed in the main window.
The protocol to use when connecting to the remote session, for example VNC.
The IP or DNS address and display number of the remote server.
Credentials to use for remote authentication. Leave empty for no authentication.
Select the best options according to your connection speed and quality.
Select the
tab to enter more specific settings.If the communication between the client and the remote server is not encrypted, activate
, otherwise the connection fails.Select the
tab for advanced SSH tunneling and authentication options.Confirm with
. Your new profile will be listed in the main window.You can either start a previously saved session, or quick-start a remote session without saving the connection details.
To start a remote session quickly without adding and saving connection details, use the drop-down box and text box at the top of the main window.
Select the communication protocol from the drop-down box, for example 'VNC', then enter the VNC server DNS or IP address followed by a colon and a display number, and confirm with Enter.
To open a specific remote session, double-click it from the list of sessions.
Remote sessions are opened in tabs of a separate window. Each tab hosts one session. The toolbar on the left of the window helps you manage the windows/sessions, such as toggle fullscreen mode, resize the window to match the display size of the session, send specific keystrokes to the session, take screenshots of the session, or set the image quality.
To edit a saved remote session, right-click its name in Remmina's main window and select . Refer to Section 4.2.3, “Adding Remote Sessions” for the description of the relevant fields.
To copy a saved remote session, right-click its name in Remmina's main window and select . In the window, change the name of the profile, optionally adjust relevant options, and confirm with .
To Delete a saved remote session, right-click its name in Remmina's main window and select . Confirm with in the next dialog.
If you need to open a remote session from the command line or from a batch file without first opening the main application window, use the following syntax:
tux >
remmina -c profile_name.remmina
Remmina's profile files are stored in the
.local/share/remmina/
directory in your home
directory. To determine which profile file belongs to the session you want
to open, run Remmina, click the session name in the main window, and read
the path to the profile file in the window's status line at the bottom.
While Remmina is not running, you can rename the profile file to a more
reasonable file name, such as sle15.remmina
. You can
even copy the profile file to your custom directory and run it using the
remmina -c
command from there.
A one-time session is initiated by the remote client. It starts a graphical login screen on the server. This way you can choose the user which starts the session and, if supported by the login manager, the desktop environment. When you terminate the client connection to such a VNC session, all applications started within that session will be terminated, too. One-time VNC sessions cannot be shared, but it is possible to have multiple sessions on a single host at the same time.
Start
› › .Check
.Activate
if you plan to access the VNC session in a Web browser window.If necessary, also check
(for example, when your network interface is configured to be in the External Zone). If you have more than one network interface, restrict opening the firewall ports to a specific interface via .Confirm your settings with
.In case not all needed packages are available yet, you need to approve the installation of missing packages.
YaST makes changes to the display manager settings. You need to log out of your current graphical session and restart the display manager for the changes to take effect.
The default configuration on openSUSE Leap serves sessions with a
resolution of 1024x768 pixels at a color depth of 16-bit. The sessions are
available on ports 5901
for
“regular” VNC viewers (equivalent to VNC display
1
) and on port
5801
for Web browsers.
Other configurations can be made available on different ports, see Section 4.3.3, “Configuring One-time VNC Sessions”.
VNC display numbers and X display numbers are independent in one-time sessions. A VNC display number is manually assigned to every configuration that the server supports (:1 in the example above). Whenever a VNC session is initiated with one of the configurations, it automatically gets a free X display number.
By default, both the VNC client and server try to communicate securely via a self-signed SSL certificate, which is generated after installation. You can either use the default one, or replace it with your own. When using the self-signed certificate, you need to confirm its signature before the first connection—both in the VNC viewer and the Web browser.
To connect to a one-time VNC session, a VNC viewer must be installed, see
also Section 4.1, “The vncviewer
Client”. Alternatively use a
JavaScript-capable Web browser to view the VNC session by entering the
following URL: http://jupiter.example.com:5801
You can skip this section, if you do not need or want to modify the default configuration.
One-time VNC sessions are started via the systemd
socket
xvnc.socket
. By default it offers six
configuration blocks: three for VNC viewers (vnc1
to
vnc3
), and three serving a JavaScript client
(vnchttpd1
to vnchttpd3
). By default
only vnc1
and vnchttpd1
are active.
To activate the VNC server socket at boot time, run the following command:
tux >
sudo
systemctl enable xvnc.socket
To start the socket immediately, run:
tux >
sudo
systemctl start xvnc.socket
The Xvnc
server can be configured via the
server_args
option. For a list of options, see
Xvnc --help
.
When adding custom configurations, make sure they are not using ports that are already in use by other configurations, other services, or existing persistent VNC sessions on the same host.
Activate configuration changes by entering the following command:
tux >
sudo
systemctl reload xvnc.socket
When activating Remote Administration as described in
Procedure 4.1, “Enabling One-time VNC Sessions”, the ports
5801
and
5901
are opened in the firewall.
If the network interface serving the VNC sessions is protected by a
firewall, you need to manually open the respective ports when activating
additional ports for VNC sessions. See
Book “Security and Hardening Guide”, Chapter 25 “Masquerading and Firewalls” for instructions.
A persistent session can be accessed from multiple clients simultaneously. This is ideal for demonstration purposes where one client has full access and all other clients have view-only access. Another use case are training sessions where the trainer might need access to the trainee's desktop.
To connect to a persistent VNC session, a VNC viewer must be installed.
Refer to Section 4.1, “The vncviewer
Client” for more details. Alternatively
use a JavaScript-capable Web browser to view the VNC session by entering the
following URL: http://jupiter.example.com:5801
There are two types of persistent VNC sessions:
vncserver
#Edit sourceThis type of persistent VNC session is initiated on the server. The session and all applications started in this session run regardless of client connections until the session is terminated. Access to persistent sessions is protected by two possible types of passwords:
a regular password that grants full access or
an optional view-only password that grants a non-interactive (view-only) access.
A session can have multiple client connections of both kinds at once.
vncserver
#Open a shell and make sure you are logged in as the user that should own the VNC session.
If the network interface serving the VNC sessions is protected by a firewall, you need to manually open the port used by your session in the firewall. If starting multiple sessions you may alternatively open a range of ports. See Book “Security and Hardening Guide”, Chapter 25 “Masquerading and Firewalls” for details on how to configure the firewall.
vncserver
uses the ports
5901
for display
:1
, 5902
for
display :2
, and so on. For persistent sessions, the
VNC display and the X display usually have the same number.
To start a session with a resolution of 1024x768 pixel and with a color depth of 16-bit, enter the following command:
vncserver -alwaysshared -geometry 1024x768 -depth 16
The vncserver
command picks an unused display number
when none is given and prints its choice. See man 1
vncserver
for more options.
When running vncserver
for the first time, it asks for a
password for full access to the session. If needed, you can also provide a
password for view-only access to the session.
The password(s) you are providing here are also used for future sessions
started by the same user. They can be changed with the
vncpasswd
command.
Make sure to use strong passwords of significant length (eight or more characters). Do not share these passwords.
To terminate the session shut down the desktop environment that runs inside the VNC session from the VNC viewer as you would shut it down if it was a regular local X session.
If you prefer to manually terminate a session, open a shell on the VNC
server and make sure you are logged in as the user that owns the VNC
session you want to terminate. Run the following command to terminate the
session that runs on display :1
: vncserver
-kill :1
Persistent VNC sessions can be configured by editing
$HOME/.vnc/xstartup
. By default this shell script
starts the same GUI/window manager it was started from. In openSUSE Leap
this will either be GNOME or IceWM. If you want to start your session
with a window manager of your choice, set the variable
WINDOWMANAGER
:
WINDOWMANAGER=gnome vncserver -geometry 1024x768 WINDOWMANAGER=icewm vncserver -geometry 1024x768
Persistent VNC sessions are configured in a single per-user configuration. Multiple sessions started by the same user will all use the same start-up and password files.
vncmanager
#Edit sourceStart
› › .Activate
.Activate
if you plan to access the VNC session in a Web browser window.If necessary, also check
(for example, when your network interface is configured to be in the External Zone). If you have more than one network interface, restrict opening the firewall ports to a specific interface via .Confirm your settings with
.In case not all needed packages are available yet, you need to approve the installation of missing packages.
YaST makes changes to the display manager settings. You need to log out of your current graphical session and restart the display manager for the changes to take effect.
After you enable the VNC session management as described in Procedure 4.3, “Enabling Persistent VNC Sessions”, you can normally connect to
the remote session with your favorite VNC viewer, such as
vncviewer
or Remmina. You will be presented with the
login screen. After you log in, the 'VNC' icon will appear in the system
tray of your desktop environment. Click the icon to open the window. If it does not appear or if your desktop
environment does not support icons in the system tray, run
vncmanager-controller
manually.
There are several settings that influence the VNC session's behavior:
This is equivalent to a one-time session. It is not visible to others and will be terminated after you disconnect from it. Refer to Section 4.3, “Configuring One-time Sessions on the VNC Server” for more information.
The session is visible to other users and keeps running even after you disconnect from it.
Here you can specify the name of the persistent session so that it is easily identified when reconnecting.
The session will be freely accessible without having to log in under user credentials.
You need to log in with a valid user name and password to access the session. Lists the valid user names in the
text box.Prevents multiple users from joining the session at the same time.
Allows multiple users to join the persistent session at the same time. Useful for remote presentations or training sessions.
Confirm with
.After you set up a persistent VNC session as described in Section 4.4.2.1, “Configuring Persistent VNC Sessions”, you can join it with your VNC viewer. After your VNC client connects to the server, you will be prompted to choose whether you want to create a new session, or join the existing one:
After you click the name of the existing session, you may be asked for login credentials, depending on the persistent session settings.
If the VNC server is set up properly, all communication between the VNC server and the client is encrypted. The authentication happens at the beginning of the session; the actual data transfer only begins afterward.
Whether for a one-time or a persistent VNC session, security options are
configured via the -securitytypes
parameter of the
/usr/bin/Xvnc
command located on the
server_args
line. The -securitytypes
parameter selects both authentication method and encryption. It has the
following options:
No authentication.
Authentication using custom password.
Authentication using PAM to verify user's password.
No encryption.
Anonymous TLS encryption. Everything is encrypted, but there is no verification of the remote host. So you are protected against passive attackers, but not against man-in-the-middle attackers.
TLS encryption with certificate. If you use a self-signed certificate, you will be asked to verify it on the first connection. On subsequent connections you will be warned only if the certificate changed. So you are protected against everything except man-in-the-middle on the first connection (similar to typical SSH usage). If you use a certificate signed by a certificate authority matching the machine name, then you get full security (similar to typical HTTPS usage).
With X509 based encryption, you need to specify the path to the X509
certificate and the key with -X509Cert
and
-X509Key
options.
If you select multiple security types separated by comma, the first one supported and allowed by both client and server will be used. That way you can configure opportunistic encryption on the server. This is useful if you need to support VNC clients that do not support encryption.
On the client, you can also specify the allowed security types to prevent a downgrade attack if you are connecting to a server which you know has encryption enabled (although our vncviewer will warn you with the "Connection not encrypted!" message in that case).
Sophisticated system configurations require specific disk setups. All common
partitioning tasks can be done during the installation. To get persistent
device naming with block devices, use the block devices below
/dev/disk/by-id
or
/dev/disk/by-uuid
. Logical Volume Management (LVM) is a
disk partitioning scheme that is designed to be much more flexible than the
physical partitioning used in standard setups. Its snapshot functionality
enables easy creation of data backups. Redundant Array of Independent Disks
(RAID) offers increased data integrity, performance, and fault tolerance.
openSUSE Leap also supports multipath I/O . There is also the
option to use iSCSI as a networked disk.
Note that for partitioning purposes, disk space is measured in binary
units, rather than in decimal units. For example, if you enter sizes of
1GB
, 1GiB
or 1G
,
they all signify 1 GiB (Gibibyte), as opposed to 1 GB (Gigabyte).
1 GiB = 1 073 741 824 bytes.
1 GB = 1 000 000 000 bytes.
1 GiB ≈ 1.07 GB.
With the Expert Partitioner, shown in Figure 5.1, “The YaST Partitioner”, manually modify the partitioning of one or several hard disks. You can add, delete, resize, and edit partitions, or access the soft RAID, and LVM configuration.
Although it is possible to repartition your system while it is running, the risk of making a mistake that causes data loss is very high. Try to avoid repartitioning your installed system and always create a complete backup of your data before attempting to do so.
All existing or suggested partitions on all connected hard disks are
displayed in the list of /dev/sda
. Partitions are listed as parts of
these devices, such as
/dev/sda1
. The size, type,
encryption status, file system, and mount point of the hard disks and their
partitions are also displayed. The mount point describes where the partition
appears in the Linux file system tree.
Several functional views are available on the left hand RAID
, Volume Management
,
Crypt Files
), and view file systems with additional
features, such as Btrfs, NFS, or TMPFS
.
If you run the expert dialog during installation, any free hard disk space is also listed and automatically selected. To provide more disk space to openSUSE Leap, free the needed space by going from the bottom toward the top in the list of partitions.
openSUSE Leap allows to use and create different partition tables. In some cases the partition table is called disk label. The partition table is important to the boot process of your computer. To boot your machine from a partition in a newly created partition table, make sure that the table format is supported by the firmware.
To change the partition table, click the relevant disk name in the
and choose › .The master boot record (MBR) is the legacy partition table used on IBM PCs. It is sometimes also called an MS-DOS partition table. The MBR only supports four primary partitions. If the disk already has an MBR, openSUSE Leap allows you to create additional partitions in it which can be used as the installation target.
The limit of four partitions can be overcome by creating an extended partition. The extended partition itself is a primary partition and can contain more logical partitions.
UEFI firmware usually supports booting from MBR in the legacy mode.
UEFI computers use a GUID Partition Table (GPT) by default. openSUSE Leap will create a GPT on a disk if no other partition table exists.
Old BIOS firmware does not support booting from GPT partitions.
You need a GPT partition table to use one of the following features:
More than four primary partitions
UEFI Secure Boot
Use disks larger than 2 TB
GPT partitions created with Parted 3.1 or earlier used the Microsoft
Basic Data partition type instead of the newer Linux-specific GPT GUID.
Newer versions of Parted will set the misleading flag
msftdata
on such partitions. This will also lead to
various disk tools labeling the partition as a Windows Data
Partition or similar.
To remove the flag, run:
root #
parted DEVICE set PARTITION_NUMBER msftdata off
The YaST Partitioner can create and format partitions with several
file systems. The default file system used by openSUSE Leap is
Btrfs
. For details, see
Section 5.1.2.2, “Btrfs Partitioning”.
Other commonly used file systems are available:
Ext2
, Ext3
,
Ext4
, FAT
,
XFS
, Swap
, and UDF
.
To create a partition select
and then a hard disk with free space. The actual modification can be done in the tab:Click MBR, specify to create a primary or extended partition. Within the extended partition, you can create several logical partitions. For details, see Section 5.1.1, “Partition Tables”.
to create a new partition. When usingSpecify the size of the new partition. You can either choose to occupy all the free unpartitioned space, or enter a custom size.
Select the file system to use and a mount point. YaST suggests a mount point for each partition created. To use a different mount method, like mount by label, select
.Specify additional file system options if your setup requires them. This is necessary, for example, if you need persistent device names. For details on the available options, refer to Section 5.1.3, “Editing a Partition”.
Click
to apply your partitioning setup and leave the partitioning module.If you created the partition during installation, you are returned to the installation overview screen.
The default file system for the root partition is Btrfs. For details, see Chapter 3, System Recovery and Snapshot Management with Snapper. The root file system is the default subvolume and it is not listed in the list of created subvolumes. As a default Btrfs subvolume, it can be mounted as a normal file system.
The default partitioning setup suggests the root partition as
Btrfs with /boot
being a directory. To
encrypt the root partition, make sure to use the GPT partition
table type instead of the default MSDOS type. Otherwise the GRUB2
boot loader may not have enough space for the second stage loader.
It is possible to create snapshots of Btrfs subvolumes—either
manually, or automatically based on system events. For example when
making changes to the file system, zypper
invokes the snapper
command to create snapshots
before and after the change. This is useful if you are not
satisfied with the change zypper
made and want
to restore the previous state. As snapper
invoked by zypper
creates snapshots of the
root file system by default, it makes sense to
exclude specific directories from snapshots. This is the reason
YaST suggests creating the following separate subvolumes:
/boot/grub2/i386-pc
,
/boot/grub2/x86_64-efi
,
/boot/grub2/powerpc-ieee1275
,
/boot/grub2/s390x-emu
A rollback of the boot loader configuration is not supported. The directories listed above are architecture-specific. The first two directories are present on AMD64/Intel 64 machines, the latter two on IBM POWER and on IBM Z, respectively.
/home
If /home
does not reside on a separate partition, it
is excluded to avoid data loss on rollbacks.
/opt
Third-party products usually get installed to /opt
. It
is excluded to avoid uninstalling these applications on rollbacks.
/srv
Contains data for Web and FTP servers. It is excluded to avoid data loss on rollbacks.
/tmp
All directories containing temporary files and caches are excluded from snapshots.
/usr/local
This directory is used when manually installing software. It is excluded to avoid uninstalling these installations on rollbacks.
/var
This directory contains many variable files, including logs, temporary
caches, third party products in /var/opt
, and is the
default location for virtual machine images and databases. Therefore this
subvolume is created to exclude all of this variable data from snapshots
and has Copy-On-Write disabled.
Since saved snapshots require more disk space, it is recommended to
reserve enough space for Btrfs. While the minimum size for a root Btrfs
partition with snapshots and default subvolumes is 16 GB, SUSE
recommends at least 32 GB, or more if /home
does not reside on a separate partition.
Subvolumes of a Btrfs partition can be now managed with the YaST
module. You can add new or remove existing subvolumes.Start the YaST
with › .Choose
in the left pane.Select the Btrfs partition whose subvolumes you need to manage and click
.
Click @/.snapshots/xyz/snapshot
entries—each
of these subvolumes belongs to one existing snapshot.
Depending on whether you want to add or remove subvolumes, do the following:
To remove a subvolume, select it from the list of
and click .To add a new subvolume, enter its name to the
text box and click .Confirm with
and .Leave the partitioner with
.When you create a new partition or modify an existing partition, you can set various parameters. For new partitions, the default parameters set by YaST are usually sufficient and do not require any modification. To edit your partition setup manually, proceed as follows:
Select the partition.
Click
to edit the partition and set the parameters:Even if you do not want to format the partition at this stage, assign it a file system ID to ensure that the partition is registered correctly. Typical values are
, , , and .To change the partition file system, click
and select file system type in the list.openSUSE Leap supports several types of file systems. Btrfs is the Linux file system of choice for the root partition because of its advanced features. It supports copy-on-write functionality, creating snapshots, multi-device spanning, subvolumes, and other useful techniques. XFS, Ext3, and Ext4 are journaling file systems. These file systems can restore the system very quickly after a system crash, using write processes logged during the operation. Ext2 is not a journaling file system, but it is adequate for smaller partitions because it does not require much disk space for management.
The default file system for the root partition is Btrfs. The default file system for additional partitions is XFS.
The UDF file system can be used on optical rewritable and non-rewritable media, USB flash drives and hard disks. It is supported by multiple operating systems.
Swap is a special format that allows the partition to be used as a virtual memory. Create a swap partition of at least 256 MB. However, if you use up your swap space, consider adding memory to your system instead of adding swap space.
Changing the file system and reformatting partitions irreversibly deletes all data from the partition.
For details on the various file systems, refer to Storage Administration Guide.
If you activate the encryption, all data is written to the hard disk in encrypted form. This increases the security of sensitive data, but reduces the system speed, as the encryption takes some time to process. More information about the encryption of file systems is provided in Book “Security and Hardening Guide”, Chapter 14 “Encrypting Partitions and Files”.
Specify the directory where the partition should be mounted in the file system tree. Select from YaST suggestions or enter any other name.
Specify various parameters contained in the global file system
administration file (/etc/fstab
). The default
settings should suffice for most setups. You can, for example, change
the file system identification from the device name to a volume label.
In the volume label, use all characters except /
and
space.
To get persistent devices names, use the mount option openSUSE Leap, persistent device names are enabled by default.
, or . In
If you prefer to mount the partition by its label, you need to define
one in the HOME
for a partition
intended to mount to /home
.
If you intend to use quotas on the file system, use the mount option Book “Start-Up”, Chapter 5 “Managing Users with YaST”, Section 5.3.3 “Managing Quotas”.
. This must be done before you can define quotas for users in the YaST module. For further information on how to configure user quota, refer toSelect
to save the changes.To resize an existing file system, select the partition and use
. Note, that it is not possible to resize partitions while mounted. To resize partitions, unmount the relevant partition before running the partitioner.After you select a hard disk device (like
) in the pane, you can access the menu in the lower right part of the window. The menu contains the following commands:This option helps you create a new partition table on the selected device.
Creating a new partition table on a device irreversibly removes all the partitions and their data from that device.
This option helps you clone the device partition layout (but not the data) to other available disk devices.
After you select the host name of the computer (the top-level of the tree in the
pane), you can access the menu in the lower right part of the window. The menu contains the following commands:To access SCSI over IP block devices, you first need to configure iSCSI. This results in additionally available devices in the main partition list.
Selecting this option helps you configure the multipath enhancement to the supported mass storage devices.
The following section includes a few hints and tips on partitioning that should help you make the right decisions when setting up your system.
Note, that different partitioning tools may start counting the cylinders of
a partition with 0
or with 1
. When
calculating the number of cylinders, you should always use the difference
between the last and the first cylinder number and add one.
swap
#Edit sourceSwap is used to extend the available physical memory. It is then possible to use more memory than physical RAM available. The memory management system of kernels before 2.4.10 needed swap as a safety measure. Then, if you did not have twice the size of your RAM in swap, the performance of the system suffered. These limitations no longer exist.
Linux uses a page called “Least Recently Used” (LRU) to select pages that might be moved from memory to disk. Therefore, running applications have more memory available and caching works more smoothly.
If an application tries to allocate the maximum allowed memory, problems with swap can arise. There are three major scenarios to look at:
The application gets the maximum allowed memory. All caches are freed, and thus all other running applications are slowed. After a few minutes, the kernel's out-of-memory kill mechanism activates and kills the process.
At first, the system slows like a system without swap. After all physical RAM has been allocated, swap space is used as well. At this point, the system becomes very slow and it becomes impossible to run commands from remote. Depending on the speed of the hard disks that run the swap space, the system stays in this condition for about 10 to 15 minutes until the out-of-memory kill mechanism resolves the issue. Note that you will need a certain amount of swap if the computer needs to perform a “suspend to disk”. In that case, the swap size should be large enough to contain the necessary data from memory (512 MB–1GB).
It is better to not have an application that is out of control and swapping excessively in this case. If you use such application, the system will need many hours to recover. In the process, it is likely that other processes get timeouts and faults, leaving the system in an undefined state, even after terminating the faulty process. In this case, do a hard machine reboot and try to get it running again. Lots of swap is only useful if you have an application that relies on this feature. Such applications (like databases or graphics manipulation programs) often have an option to directly use hard disk space for their needs. It is advisable to use this option instead of using lots of swap space.
If your system is not out of control, but needs more swap after some time, it is possible to extend the swap space online. If you prepared a partition for swap space, add this partition with YaST. If you do not have a partition available, you can also use a swap file to extend the swap. Swap files are generally slower than partitions, but compared to physical RAM, both are extremely slow so the actual difference is negligible.
To add a swap file in the running system, proceed as follows:
Create an empty file in your system. For example, to add a
swap file with 128 MB swap at
/var/lib/swap/swapfile
, use the commands:
tux >
sudo
mkdir -p /var/lib/swaptux >
sudo
dd if=/dev/zero of=/var/lib/swap/swapfile bs=1M count=128
Initialize this swap file with the command
tux >
sudo
mkswap /var/lib/swap/swapfile
mkswap
Do not reformat existing swap partitions with mkswap
if possible. Reformatting with mkswap
will change
the UUID value of the swap partition. Either reformat via YaST (which
will update /etc/fstab
) or adjust
/etc/fstab
manually.
Activate the swap with the command
tux >
sudo
swapon /var/lib/swap/swapfile
To disable this swap file, use the command
tux >
sudo
swapoff /var/lib/swap/swapfile
Check the current available swap spaces with the command
tux >
cat /proc/swaps
Note that at this point, it is only temporary swap space. After the next reboot, it is no longer used.
To enable this swap file permanently, add the following line to
/etc/fstab
:
/var/lib/swap/swapfile swap swap defaults 0 0
From the
, access the LVM configuration by clicking the item in the pane. However, if a working LVM configuration already exists on your system, it is automatically activated upon entering the initial LVM configuration of a session. In this case, all disks containing a partition (belonging to an activated volume group) cannot be repartitioned. The Linux kernel cannot reread the modified partition table of a hard disk when any partition on this disk is in use. If you already have a working LVM configuration on your system, physical repartitioning should not be necessary. Instead, change the configuration of the logical volumes.
At the beginning of the physical volumes (PVs), information about the volume
is written to the partition. To reuse such a partition for other non-LVM
purposes, it is advisable to delete the beginning of this volume. For
example, in the VG system
and PV
/dev/sda2
, do this with the command:
dd
if=/dev/zero of=/dev/sda2 bs=512 count=1
The file system used for booting (the root file system or
/boot
) must not be stored on an LVM logical volume.
Instead, store it on a normal physical partition.
This section explains specific steps to take when configuring LVM.
Using LVM is sometimes associated with increased risk such as data loss. Risks also include application crashes, power failures, and faulty commands. Save your data before implementing LVM or reconfiguring volumes. Never work without a backup.
The YaST LVM configuration can be reached from the YaST Expert Partitioner (see Section 5.1, “Using the Expert Partitioner”) within the item in the pane. The Expert Partitioner allows you to edit and delete existing partitions and create new ones that need to be used with LVM.
The first task is to create physical volumes that provide space to a volume group:
Select a hard disk from
.Change to the
tab.Click
and enter the desired size of the PV on this disk.Use
and change the to . Do not mount this partition.Repeat this procedure until you have defined all the desired physical volumes on the available disks.
If no volume group exists on your system, you must add one (see Figure 5.3, “Creating a Volume Group”). It is possible to create additional groups by clicking in the pane, and then on . One single volume group is usually sufficient.
Enter a name for the VG, for example, system
.
Select the desired
. This value defines the size of a physical block in the volume group. All the disk space in a volume group is handled in blocks of this size.Add the prepared PVs to the VG by selecting the device and clicking Ctrl while selecting the devices.
. Selecting several devices is possible by holdingSelect
to make the VG available to further configuration steps.If you have multiple volume groups defined and want to add or remove PVs, select the volume group in the
list and click . In the following window, you can add or remove PVs to the selected volume group.After the volume group has been filled with PVs, define the LVs which the operating system should use in the next dialog. Choose the current volume group and change to the
tab. , , , and LVs as needed until all space in the volume group has been occupied. Assign at least one LV to each volume group.Click
and go through the wizard-like pop-up that opens:
Enter the name of the LV. For a partition that should be mounted to
/home
, a name like HOME
could be
used.
Select the type of the LV. It can be either
, , or . Note that you need to create a thin pool first, which can store individual thin volumes. The big advantage of thin provisioning is that the total sum of all thin volumes stored in a thin pool can exceed the size of the pool itself.Select the size and the number of stripes of the LV. If you have only one PV, selecting more than one stripe is not useful.
Choose the file system to use on the LV and the mount point.
By using stripes it is possible to distribute the data stream in the LV among several PVs (striping). However, striping a volume can only be done over different PVs, each providing at least the amount of space of the volume. The maximum number of stripes equals to the number of PVs, where Stripe "1" means "no striping". Striping only makes sense with PVs on different hard disks, otherwise performance will decrease.
YaST cannot, at this point, verify the correctness of your entries concerning striping. Any mistake made here is apparent only later when the LVM is implemented on disk.
If you have already configured LVM on your system, the existing logical volumes can also be used. Before continuing, assign appropriate mount points to these LVs. With
, return to the YaST Expert Partitioner and finish your work there.This section describes actions required to create and configure various types of RAID. .
The YaST Section 5.1, “Using the Expert Partitioner”. This partitioning tool enables you to edit and delete existing partitions and create new ones to be used with soft RAID:
configuration can be reached from the YaST Expert Partitioner, described inSelect a hard disk from
.Change to the
tab.Click
and enter the desired size of the raid partition on this disk.Use
and change the to . Do not mount this partition.Repeat this procedure until you have defined all the desired physical volumes on the available disks.
For RAID 0 and RAID 1, at least two partitions are needed—for RAID 1, usually exactly two and no more. If RAID 5 is used, at least three partitions are required, RAID 6 and RAID 10 require at least four partitions. It is recommended to use partitions of the same size only. The RAID partitions should be located on different hard disks to decrease the risk of losing data if one is defective (RAID 1 and 5) and to optimize the performance of RAID 0. After creating all the partitions to use with RAID, click
› to start the RAID configuration.In the next dialog, choose between RAID levels 0, 1, 5, 6 and 10. Then, select all partitions with either the “Linux RAID” or “Linux native” type that should be used by the RAID system. No swap or DOS partitions are shown.
To add a previously unassigned partition to the selected RAID volume, first click the partition then
. Assign all partitions reserved for RAID. Otherwise, the space on the partition remains unused. After assigning all partitions, click to select the available .
In this last step, set the file system to use, encryption and the mount
point for the RAID volume. After completing the configuration with
/dev/md0
device and
others indicated with RAID in the Expert Partitioner.
Check the file /proc/mdstat
to find out whether a RAID
partition has been damaged. If Th system fails, shut down your Linux system
and replace the defective hard disk with a new one partitioned the same way.
Then restart your system and enter the command mdadm /dev/mdX --add
/dev/sdX
. Replace 'X' with your particular device identifiers.
This integrates the hard disk automatically into the RAID system and fully
reconstructs it.
Note that although you can access all data during the rebuild, you may encounter some performance issues until the RAID has been fully rebuilt.
Configuration instructions and more details for soft RAID can be found at:
Linux RAID mailing lists are available, such as http://marc.info/?l=linux-raid.
openSUSE Leap supports the parallel installation of multiple kernel versions. When installing a second kernel, a boot entry and an initrd are automatically created, so no further manual configuration is needed. When rebooting the machine, the newly added kernel is available as an additional boot parameter.
Using this functionality, you can safely test kernel updates while being able to always fall back to the proven former kernel. To do this, do not use the update tools (such as the YaST Online Update or the updater applet), but instead follow the process described in this chapter.
It is recommended to check your boot loader configuration after having installed another kernel to set the default boot entry of your choice. See Section 12.3, “Configuring the Boot Loader with YaST” for more information.
Installing multiple versions of a software package (multiversion support) is enabled by default from openSUSE Leap. To verify this setting, proceed as follows:
Open /etc/zypp/zypp.conf
with the editor of your
choice as root
.
Search for the string multiversion
. If multiversion is
enabled for all kernel packages capable of this feature, the following
line appears uncommented:
multiversion = provides:multiversion(kernel)
To restrict multiversion support to certain kernel flavors, add the
package names as a comma-separated list to the
multiversion
option in
/etc/zypp/zypp.conf
—for example
multiversion = kernel-default,kernel-default-base,kernel-source
Save your changes.
Make sure that required vendor provided kernel modules (Kernel Module Packages) are also installed for the new updated kernel. The kernel update process will not warn about eventually missing kernel modules because package requirements are still fulfilled by the old kernel that is kept on the system.
When frequently testing new kernels with multiversion support enabled, the
boot menu quickly becomes confusing. Since a /boot
partition usually has limited space you also might run into trouble with
/boot
overflowing. While you can delete unused kernel
versions manually with YaST or Zypper (as described below), you can also
configure libzypp
to automatically
delete kernels no longer used. By default no kernels are deleted.
Open /etc/zypp/zypp.conf
with the editor of your
choice as root
.
Search for the string multiversion.kernels
and
activate this option by uncommenting the line. This option takes a
comma-separated list of the following values:
5.3.18-8
:
keep the kernel with the specified version number
latest
:
keep the kernel with the highest version number
latest-N
:
keep the kernel with the Nth highest version number
running
:
keep the running kernel
oldest
:
keep the kernel with the lowest version number (the one that was
originally shipped with openSUSE Leap)
oldest+N
.
keep the kernel with the Nth lowest version number
Here are some examples
multiversion.kernels = latest,running
Keep the latest kernel and the one currently running. This is similar to not enabling the multiversion feature, except that the old kernel is removed after the next reboot and not immediately after the installation.
multiversion.kernels = latest,latest-1,running
Keep the last two kernels and the one currently running.
multiversion.kernels = latest,running,5.3.18-8
Keep the latest kernel, the one currently running, and 5.3.18-8.
Unless you are using a special setup, always keep the
kernel marked running
.
If you do not keep the running kernel, it will be deleted when updating the kernel. In turn, this means that all of the running kernel's modules are also deleted and cannot be loaded anymore.
If you decide not to keep the running kernel, always reboot immediately after a kernel upgrade to avoid issues with modules.
You want to make sure that an old kernel will only be deleted after the system has rebooted successfully with the new kernel.
Change the following line in /etc/zypp/zypp.conf
:
multiversion.kernels = latest,running
The previous parameters tell the system to keep the latest kernel and the running one only if they differ.
You want to keep one or more kernel versions to have one or more “spare” kernels.
This can be useful if you need kernels for testing. If something goes wrong (for example, your machine does not boot), you still can use one or more kernel versions which are known to be good.
Change the following line in /etc/zypp/zypp.conf
:
multiversion.kernels = latest,latest-1,latest-2,running
When you reboot your system after the installation of a new kernel, the
system will keep three kernels: the current kernel (configured as
latest,running
) and its two immediate predecessors
(configured as latest-1
and latest-2
).
You make regular system updates and install new kernel versions. However, you are also compiling your own kernel version and want to make sure that the system will keep them.
Change the following line in /etc/zypp/zypp.conf
:
multiversion.kernels = latest,5.3.18-8,running
When you reboot your system after the installation of a new kernel, the
system will keep two kernels: the new and running kernel (configured as
latest,running
) and your self-compiled kernel
(configured as 5.3.18-8
).
You can install or remove multiple kernels with YaST:
Start YaST and open the software manager via
› .List all packages capable of providing multiple versions by choosing
› › .Select a package and open its
tab in the bottom pane on the left.To install a package, click the check box next to it. A green check mark indicates it is selected for installation.
To remove an already installed package (marked with a white check mark),
click the check box next to it until a red X
indicates it is
selected for removal.
Click
to start the installation.
You can install or remove multiple kernels with zypper
:
Use the command zypper se -s 'kernel*'
to display a
list of all kernel packages available:
S | Name | Type | Version | Arch | Repository --+----------------+------------+-----------------+--------+------------------- i+ | kernel-default | package | 5.3.18-8.2 | x86_64 | (System Packages) v | kernel-default | package | 5.3.18-10.1 | x86_64 | SLE-Module-Basesystem15-SP2-Pool | kernel-default-base | package | 5.3.18-10.1.4.8 | x86_64 | SLE-Module-Basesystem15-SP2-Pool | kernel-default-devel | package | 5.3.18-10.1 | x86_64 | SLE-Module-Basesystem15-SP2-Pool | kernel-devel | package | 5.3.18-10.1 | noarch | SLE-Module-Basesystem15-SP2-Pool i | kernel-firmware | package | 20200107-3.12.1 | noarch | SLE-Module-Basesystem15-SP2-Pool
Specify the exact version when installing:
tux >
sudo
zypper in kernel-default-5.3.18-8.2
When uninstalling a kernel, use the commands zypper se -si
'kernel*'
to list all kernels installed and zypper
rm
PACKAGENAME-VERSION to remove the
package.
Kernel:HEAD
#Edit source
Add the Kernel:HEAD
repository with (the repository
is added using the alias kernel-repo
):
tux >
sudo
zypper ar \ http://download.opensuse.org/repositories/Kernel:/HEAD/standard/ \ kernel-repo
To refresh repositories, run:
tux >
sudo
zypper ref
To upgrade the kernel to the latest version in the
Kernel:HEAD
repository, run:
tux >
sudo
zypper dist-upgrade --allow-vendor-change --from kernel-repo
Reboot the machine.
Kernel:HEAD
May Break the System
Installing a kernel from Kernel:HEAD
should never be
necessary, because important fixes are backported by SUSE and are made
available as official updates. Installing the latest kernel only makes
sense for kernel developers and kernel testers. If installing from
Kernel:HEAD
, be aware that it may break your system.
Make sure to always have the original kernel available for booting as
well.
openSUSE Leap includes the X.org server, Wayland and the GNOME desktop. This chapter describes the configuration of the graphical user interface for all users.
The X.org server is the de facto standard for implementing the X11 protocol. X is network-based, enabling applications started on one host to be displayed on another host connected over any kind of network (LAN or Internet).
Usually, the X Window System needs no configuration. The hardware is
dynamically detected during X start-up. The use of
xorg.conf
is therefore deprecated. If you still
need to specify custom options to change the way X behaves, you can
still do so by modifying configuration files under
/etc/X11/xorg.conf.d/
.
In openSUSE Leap 15.2 Wayland is included as an alternative to the X.org server. It can be selected during the installation.
Install the package xorg-docs
to
get more in-depth information about X11. man 5 xorg.conf
tells you more about the format of the manual configuration (if needed).
More information on the X11 development can be found on the project's home
page at http://www.x.org.
Drivers are found in xf86-video-*
packages, for
example xf86-video-ati
. Many of the drivers
delivered with these packages are described in detail in the related manual
page. For example, if you use the ati
driver, find more
information about this driver in man 4 ati
.
Information about third-party drivers is available in
/usr/share/doc/packages/<package_name>
.
For example, the documentation of x11-video-nvidiaG03
is available in
/usr/share/doc/packages/x11-video-nvidiaG04
after the package was installed.
Fonts in Linux can be categorized into two parts:
Contains a mathematical description as drawing instructions about the shape of a glyph. As such, each glyph can be scaled to arbitrary sizes without loss of quality. Before such a font (or glyph) can be used, the mathematical descriptions need to be transformed into a raster (grid). This process is called font rasterization. Font hinting (embedded inside the font) improves and optimizes the rendering result for a particular size. Rasterization and hinting is done with the FreeType library.
Common formats under Linux are PostScript Type 1 and Type 2, TrueType, and OpenType.
Consists of an array of pixels designed for a specific font size. Bitmap fonts are extremely fast and simple to render. However, compared to vector fonts, bitmap fonts cannot be scaled without losing quality. As such, these fonts are usually distributed in different sizes. These days, bitmap fonts are still used in the Linux console and sometimes in terminals.
Under Linux, Portable Compiled Format (PCF) or Glyph Bitmap Distribution Format (BDF) are the most common formats.
The appearance of these fonts can be influenced by two main aspects:
choosing a suitable font family,
rendering the font with an algorithm that achieves results comfortable for the receiver's eyes.
The last point is only relevant to vector fonts. Although the above two points are highly subjective, some defaults need to be created.
Linux font rendering systems consist of several libraries with different relations. The basic font rendering library is FreeType, which converts font glyphs of supported formats into optimized bitmap glyphs. The rendering process is controlled by an algorithm and its parameters (which may be subject to patent issues).
Every program or library which uses FreeType should consult the Fontconfig library. This library gathers font configuration from users and from the system. When a user amends their Fontconfig setting, this change will result in Fontconfig-aware applications.
More sophisticated OpenType shaping needed for scripts such as Arabic, Han or Phags-Pa and other higher level text processing is done using Harfbuzz or Pango.
To get an overview about which fonts are installed on your system, ask the
commands rpm
or fc-list
. Both will
give you a good answer, but may return a different list depending on system
and user configuration:
rpm
Invoke rpm
to see which software packages containing
fonts are installed on your system:
tux >
rpm -qa '*fonts*'
Every font package should satisfy this expression. However, the command
may return some false positives like fonts-config
(which is neither a font nor does it contain fonts).
fc-list
Invoke fc-list
to get an overview about what font
families can be accessed, whether they are installed on the system or in
your home:
tux >
fc-list ':' family
fc-list
The command fc-list
is a wrapper to the Fontconfig
library. It is possible to query a lot of interesting information from
Fontconfig—or, to be more precise, from its cache. See
man 1 fc-list
for more details.
If you want to know what an installed font family looks like, either use the
command ftview
(package
ft2demos
) or visit
http://fontinfo.opensuse.org/. For example, to display
the FreeMono font in 14 point, use ftview
like this:
tux >
ftview 14 /usr/share/fonts/truetype/FreeMono.ttf
If you need further information, go to http://fontinfo.opensuse.org/ to find out which styles (regular, bold, italic, etc.) and languages are supported.
To query which font is used when a pattern is given, use the
fc-match
command.
For example, if your pattern contains an already installed font,
fc-match
returns the file name, font family, and the
style:
tux >
fc-match 'Liberation Serif'
LiberationSerif-Regular.ttf: "Liberation Serif" "Regular"
If the desired font does not exist on your system, Fontconfig's matching rules take place and try to find the most similar fonts available. This means, your request is substituted:
tux >
fc-match 'Foo Family'
DejaVuSans.ttf: "DejaVu Sans" "Book"
Fontconfig supports aliases: a name is substituted with another family name. A typical example are the generic names such as “sans-serif”, “serif”, and “monospace”. These alias names can be substituted by real family names or even a preference list of family names:
tux >
for font in serif sans mono; do fc-match "$font" ; done
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"
The result may vary on your system, depending on which fonts are currently installed.
Fontconfig always returns a real family (if at least one is installed) according to the given request, as similar as possible. “Similarity” depends on Fontconfig's internal metrics and on the user's or administrator's Fontconfig settings.
To install a new font there are these major methods:
Manually install the font files such as *.ttf
or
*.otf
to a known font directory. If it needs to be
system-wide, use the standard directory
/usr/share/fonts
. For installation in your home
directory, use ~/.config/fonts
.
If you want to deviate from the standard directories, Fontconfig allows
you to choose another one. Let Fontconfig know by using the
<dir>
element, see
Section 7.2.5.2, “Diving into Fontconfig XML” for details.
Install fonts using zypper
. Lots of fonts are already
available as a package, be it on your SUSE distribution or in the M17N:fonts
repository. Add the repository to your list using the following command.
For example, to add a repository for openSUSE Leap 15.2:
tux >
sudo
zypper ar https://download.opensuse.org/repositories/M17N:/fonts/openSUSE_Leap_15.2/
To search for your FONT_FAMILY_NAME use this command:
tux >
zypper se 'FONT_FAMILY_NAME*fonts'
Depending on the rendering medium, and font size, the result may be unsatisfactory. For example, an average monitor these days has a resolution of 100dpi which makes pixels too big and glyphs look clunky.
There are several algorithms available to deal with low resolutions, such as anti-aliasing (grayscale smoothing), hinting (fitting to the grid), or subpixel rendering (tripling resolution in one direction). These algorithms can also differ from one font format to another.
Subpixel rendering is not used in SUSE distributions. Although FreeType2 has support for this algorithm, it is covered by several patents expiring at the end of the year 2019. Therefore, setting subpixel rendering options in Fontconfig has no effect unless the system has a FreeType2 library with subpixel rendering compiled in.
Via Fontconfig, it is possible to select a rendering algorithms for every font individually or for a set of fonts.
sysconfig
#Edit source
openSUSE Leap comes with a sysconfig
layer above
Fontconfig. This is a good starting point for experimenting with font
configuration. To change the default settings, edit the configuration file
/etc/sysconfig/fonts-config
. (or use the YaST
sysconfig module). After you have edited the file, run
fonts-config
:
tux >
sudo
/usr/sbin/fonts-config
Restart the application to make the effect visible. Keep in mind the following issues:
A few applications do need not to be restarted. For example, Firefox re-reads Fontconfig configuration from time to time. Newly created or reloaded tabs get new font configurations later.
The fonts-config
script is called automatically after
every package installation or removal (if not, it is a bug of the font
software package).
Every sysconfig variable can be temporarily overridden by the
fonts-config
command line option. See
fonts-config --help
for details.
There are several sysconfig variables which can be altered. See
man 1 fonts-config
or the help page of the YaST
sysconfig module. The following variables are examples:
Consider FORCE_HINTSTYLE
,
FORCE_AUTOHINT
, FORCE_BW
,
FORCE_BW_MONOSPACE
,
USE_EMBEDDED_BITMAPS
and
EMBEDDED_BITMAP_LANGAGES
Use PREFER_SANS_FAMILIES
,
PREFER_SERIF_FAMILIES
,
PREFER_MONO_FAMILIES
and
SEARCH_METRIC_COMPATIBLE
The following list provides some configuration examples, sorted from the “most readable” fonts (more contrast) to “most beautiful” (more smoothed).
Prefer bitmap fonts via the PREFER_*_FAMILIES
variables. Follow the example in the help section for these variables.
Be aware that these fonts are rendered black and white, not smoothed and
that bitmap fonts are available in several sizes only. Consider using
SEARCH_METRIC_COMPATIBLE="no"
to disable metric compatibility-driven family name substitutions.
Scalable fonts rendered without antialiasing can result in a similar outcome to bitmap fonts, while maintaining font scalability. Use well hinted fonts like the Liberation families. Unfortunately, there is a lack of well hinted fonts though. Set the following variable to force this method:
FORCE_BW="yes"
Render monospaced fonts without antialiasing only, otherwise use default settings:
FORCE_BW_MONOSPACE="yes"
All fonts are rendered with antialiasing. Well hinted fonts will be
rendered with the byte code interpreter (BCI) and
the rest with autohinter (hintstyle=hintslight
).
Leave all relevant sysconfig variables to the default setting.
Use fonts in CFF format. They can be considered also more readable than
the default TrueType fonts given the current improvements in FreeType2.
Try them out by following the example of
PREFER_*_FAMILIES
. Possibly make them more dark and
bold with:
SEARCH_METRIC_COMPATIBLE="no"
as they are rendered by hintstyle=hintslight
by
default. Also consider using:
SEARCH_METRIC_COMPATIBLE="no"
Even for a well hinted font, use FreeType2's autohinter. That can lead to thicker, sometimes fuzzier letter shapes with lower contrast. Set the following variable to activate this:
FORCE_AUTOHINTER="yes"
Use FORCE_HINTSTYLE
to control the level of hinting.
Fontconfig's configuration format is the eXtensible Markup
Language (XML). These few examples are not a complete reference,
but a brief overview. Details and other inspiration can be found in
man 5 fonts-conf
or in
/etc/fonts/conf.d/
.
The central Fontconfig configuration file is
/etc/fonts/fonts.conf
, which—along other
work—includes the whole /etc/fonts/conf.d/
directory. To customize Fontconfig, there are two places where you can
insert your changes:
System-wide changes.
Edit the file /etc/fonts/local.conf
(by default, it
contains an empty fontconfig
element).
User-specific changes.
Edit the file ~/.config/fontconfig/fonts.conf
.
Place Fontconfig configuration files in the
~/.config/fontconfig/conf.d/
directory.
User-specific changes overwrite any system-wide settings.
The file ~/.fonts.conf
is marked as deprecated and
should not be used anymore. Use
~/.config/fontconfig/fonts.conf
instead.
Every configuration file needs to have a fontconfig
element. As such, the minimal file looks like this:
<?xml version="1.0"?> <!DOCTYPE fontconfig SYSTEM "fonts.dtd"> <fontconfig> <!-- Insert your changes here --> </fontconfig>
If the default directories are not enough, insert the
dir
element with the respective directory:
<dir>/usr/share/fonts2</dir>
Fontconfig searches recursively for fonts.
Font-rendering algorithms can be chosen with following Fontconfig snippet (see Example 7.1, “Specifying Rendering Algorithms”):
<match target="font"> <test name="family"> <string>FAMILY_NAME</string> </test> <edit name="antialias" mode="assign"> <bool>true</bool> </edit> <edit name="hinting" mode="assign"> <bool>true</bool> </edit> <edit name="autohint" mode="assign"> <bool>false</bool> </edit> <edit name="hintstyle" mode="assign"> <const>hintfull</const> </edit> </match>
Various properties of fonts can be tested. For example, the
<test>
element can test for the font family (as
shown in the example), size interval, spacing, font format, and others.
When abandoning <test>
completely, all
<edit>
elements will be applied to every font
(global change).
<alias> <family>Alegreya SC</family> <default> <family>serif</family> </default> </alias>
<alias> <family>serif</family> <prefer> <family>Droid Serif</family> </prefer> </alias>
<alias> <family>serif</family> <accept> <family>STIXGeneral</family> </accept> </alias>
The rules from Example 7.2, “Aliases and Family Name Substitutions” create a prioritized family list (PFL). Depending on the element, different actions are performed:
<default>
from
Rule 1
This rule adds a serif
family name at the
end of the PFL.
<prefer>
from
Rule 2
This rule adds “Droid Serif” just
before the first occurrence of serif
in
the PFL, whenever Alegreya SC
is in PFL.
<accept>
from Rule 3
This rule adds a “STIXGeneral” family name just
after the first occurrence of the serif
family name in the PFL.
Putting this together, when snippets occur in the order Rule 1 - Rule 2 - Rule 3 and the user requests “Alegreya SC”, then the PFL is created as depicted in Table 7.1, “Generating PFL from Fontconfig rules”.
In Fontconfig's metrics, the family name has the highest priority over other patterns, like style, size, etc. Fontconfig checks which family is currently installed on the system. If “Alegreya SC” is installed, then Fontconfig returns it. If not, it asks for “Droid Serif”, etc.
Be careful. When the order of Fontconfig snippets is changed, Fontconfig can return different results, as depicted in Table 7.2, “Results from Generating PFL from Fontconfig Rules with Changed Order”.
Think of the <default>
alias as a classification
or inclusion of this group (if not installed). As the example shows,
<default>
should always precede the
<prefer>
and <accept>
aliases of that group.
<default>
classification is not limited to the
generic aliases serif, sans-serif and monospace. See
/usr/share/fontconfig/conf.avail/30-metric-aliases.conf
for a complex example.
The following Fontconfig snippet in
Example 7.3, “Aliases and Family Name Substitutions” creates a
serif
group. Every family in this group could substitute
others when a former font is not installed.
<alias> <family>Alegreya SC</family> <default> <family>serif</family> </default> </alias> <alias> <family>Droid Serif</family> <default> <family>serif</family> </default> </alias> <alias> <family>STIXGeneral</family> <default> <family>serif</family> </default> </alias> <alias> <family>serif</family> <accept> <family>Droid Serif</family> <family>STIXGeneral</family> <family>Alegreya SC</family> </accept> </alias>
Priority is given by the order in the <accept>
alias. Similarly, stronger <prefer>
aliases can be
used.
Example 7.2, “Aliases and Family Name Substitutions” is expanded by Example 7.4, “Aliases and Family Names Substitutions”.
<alias> <family>serif</family> <accept> <family>Liberation Serif</family> </accept> </alias>
<alias> <family>serif</family> <prefer> <family>DejaVu Serif</family> </prefer> </alias>
The expanded configuration from Example 7.4, “Aliases and Family Names Substitutions” would lead to the following PFL evolution:
Order |
Current PFL |
---|---|
Request |
|
| |
| |
| |
| |
|
In case multiple <accept>
declarations for the
same generic name exist, the declaration that is parsed last
“wins”. If possible, do not use
<accept>
after
user (/etc/fonts/conf.d/*-user.conf
) when creating
a system-wide configuration.
In case multiple <prefer
declarations for the same
generic name exist, the declaration that is parsed last
“wins”. If possible, do not use
<prefer>
before user in the system-wide
configuration.
Every <prefer>
declaration overwrites
<accept>
declarations for the same generic
name. If the administrator wants to allow the user to use
<accept>
and not only
<prefer>
, the administrator should not use
<prefer>
in the system-wide configuration. On
the other hand, as users mostly use <prefer>
,
this should not have any detrimental effect. We also see the use of
<prefer>
in system-wide configurations.
dconf
System #Edit source
Configuration of the GNOME desktop is managed with
dconf
. It is a hierarchically structured database or
registry that allows users to modify their personal settings, and system
administrators to set default or mandatory values for all users.
dconf
replaces the gconf
system of
GNOME 2.
Use dconf-editor
to view the dconf
options with a graphical user interface. Use dconf
to
access and modify configuration options with the command line.
The GNOME Tweaks
tool provides an easy-to-use
user interface for additional configuration options beyond the
normal GNOME configuration. The tool can be started from the
GNOME application menu or from the command line with
gnome-tweak-tool
.
Global dconf
configuration parameters can be set
in the /etc/dconf/db/
directory. This includes
the configuration for GDM or locking certain configuration options
for users.
Use the following procedure as an example to create a system-wide configuration:
Create a new directory that ends with a .d
in
/etc/dconf/db/
. This directory can contain an
arbitrary amount of text files with configuration options. For this
example, create the file
/etc/dconf/db/network/00-proxy
with the
following content:
# This is a comment [system/proxy/http] host='10.0.0.1' enabled=true
Parse the new configuration directives into the dconf database format:
tux >
sudo
dconf update
Add the new network
configuration database to
the default user profile, by creating the file /etc/dconf/profiles/user
.
Then add the following content:
system-db:network
The file /etc/dconf/profiles/user
is a GNOME
default that will be used. Other profiles can be defined in the
environment variable DCONF_PROFILE
.
Optional: To lock the proxy configuration for users, create the file
/etc/dconf/db/network/locks/proxy
. Then add
a line to this file with the keys that may not be changed:
/system/proxy/http/host /system/proxy/http/enabled
You can use the graphical dconf-editor
to create a
profile with one user and then use dconf dump /
to list all configuration options. The configuration options can
then be stored in a global profile.
A detailed description of the global configuration is available at https://wiki.gnome.org/Projects/dconf/SystemAdministrators.
For more information, see http://help.gnome.org/admin/.
SUSE Prime is a tool for switching between onboard Intel graphical processing units (GPUs), and NVIDIA GPUs equipped with NVIDIA's "switchable graphics" Optimus technology. Optimus provides a mechanism for easily switching between an onboard Intel GPU and a discrete NVIDIA GPU. This is designed for running a laptop in a power-saving mode, or at maximum performance: use the Intel GPU to save power, and the NVIDIA GPU for 3D applications.
SUSE Prime works only on systems running X11, not Wayland. If your system runs Wayland you may disable it and fall back to X11 (see Section 7.4.1, “Prerequisites”).
You must have a configured and working NVIDIA Optimus GPU using the NVIDIA proprietary drivers from the openSUSE community repository (see Section 7.4.3, “Installing NVIDIA Drivers”), and an onboard Intel GPU. Bumblebee, the older switching tool for NVIDIA Optimus, must not be installed.
There must not be a /etc/X11/xorg.conf
file, and no
configuration files with active "ServerLayout", "Device" or "Screen"
sections in the /etc/X11/xorg.conf.d
directory.
SUSE Prime only works with X11. Use the loginctl
command to see if your system is using X11 or Wayland:
tux >
loginctl SESSION UID USER SEAT TTY 2 1000 tux seat0tux >
loginctl show-session 2|grep Type Type=x11
If your system uses Wayland, disable it by editing
/etc/gdm/custom.conf
, and un-commenting
WaylandEnable=false
. Then reboot.
Your NVIDIA graphics card should already be installed and working. If it is not, see Section 7.4.3, “Installing NVIDIA Drivers”.
Install the suse-prime package:
tux >
sudo
zypper install suse-prime
To switch your GPU run one of the following commands, then log out and log back in:
tux >
sudo
prime-select inteltux >
sudo
prime-select intel2tux >
sudo
prime-select nvidia
Use the intel
driver when it's the modesetting driver.
intel2
is for systems that use the
xf86-video-intel driver. You can get this information by
installing and running inxi:
tux >
inxi -G
Graphics: Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
Display Server: x11(X.org 1.20.1 ) drivers: modesetting (unloaded: fbdev, vesa)
Resolution: 1920x1080@60.00hz
OpenGL: renderer: Mesa DRI Intel Haswell Desktop version: 4.5 Mesa 18.2.8
Which GPU is currently active?
tux >
sudo
/usr/sbin/prime-select get-current Driver configured: intel
If you need to identify your NVIDIA card so you know which driver to use, run the following command:
tux >
/sbin/lspci | grep VGA
Follow these steps to install the drivers with Zypper. First install the community repository for your distribution. For openSUSE Tumbleweed:
tux >
sudo
zypper addrepo --refresh https://download.nvidia.com/opensuse/tumbleweed nvidia
For openSUSE 15.2:
tux >
sudo
zypper addrepo --refresh https://download.nvidia.com/opensuse/leap/15.2 nvidia
List the available driver packages:
tux >
sudo
zypper se nvidia
Then install the drivers for your NVIDIA graphics card:
tux >
sudo
zypper se packagename
openSUSE® Leap is available for 64-bit platforms. The developers have not ported all 32-bit applications to 64-bit systems. But openSUSE Leap supports 32-bit application use in 64-bit system environments. This chapter offers a brief overview of 32-bit support implementation on 64-bit openSUSE Leap p…
Booting a Linux system involves different components and tasks. After a
firmware and hardware initialization process, which depends on the
machine's architecture, the kernel is started by means of the boot loader
GRUB 2. After this point, the boot process is completely controlled by the
operating system and handled by systemd
. systemd
provides a set of
“targets” that boot configurations for everyday usage,
maintenance or emergencies.
systemd
DaemonThe program systemd is the process with process ID 1. It is responsible for initializing the system in the required way. systemd is started directly by the kernel and resists signal 9, which normally terminates processes. All other programs are either started directly by systemd or by one of its chi…
journalctl
: Query the systemd
Journal
When systemd
replaced traditional init scripts in openSUSE Leap
(see Chapter 10, The systemd
Daemon), it introduced its own logging system
called journal. There is no need to run a
syslog
based service anymore, as all system events
are written in the journal.
This chapter describes how to configure GRUB 2, the boot loader used in openSUSE® Leap. It is the successor to the traditional GRUB boot loader—now called “GRUB Legacy”. A YaST module is available for configuring the most important settings. The boot procedure as a whole is outlined in Chapter 9, Introduction to the Boot Process. For details on Secure Boot support for UEFI machines, see Chapter 14, UEFI (Unified Extensible Firmware Interface).
Linux offers the necessary networking tools and features for integration into all types of network structures. Network access using a network card can be configured with YaST. Manual configuration is also possible. In this chapter only the fundamental mechanisms and the relevant network configuration files are covered.
UEFI (Unified Extensible Firmware Interface) is the interface between the firmware that comes with the system hardware, all the hardware components of the system, and the operating system.
This chapter starts with information about various software packages, the
virtual consoles and the keyboard layout. We talk about software components
like bash
,
cron
and
logrotate
, because they were
changed or enhanced during the last release cycles. Even if they are small
or considered of minor importance, users should change their default
behavior, because these components are often closely coupled with the
system. The chapter concludes with a section about language and
country-specific settings (I18N and L10N).
udev
The kernel can add or remove almost any device in a running system. Changes in the device state (whether a device is plugged in or removed) need to be propagated to user space. Devices need to be configured when they are plugged in and recognized. Users of a certain device need to be informed about …
openSUSE® Leap is available for 64-bit platforms. The developers have not ported all 32-bit applications to 64-bit systems. But openSUSE Leap supports 32-bit application use in 64-bit system environments. This chapter offers a brief overview of 32-bit support implementation on 64-bit openSUSE Leap platforms.
openSUSE Leap for the 64-bit platforms AMD64 and Intel 64 is designed so that existing 32-bit applications run in the 64-bit environment “out-of-the-box.” This support means that you can continue to use your preferred 32-bit applications without waiting for a corresponding 64-bit port to become available.
openSUSE Leap does not support compilation of 32-bit applications. It only offers runtime support for 32-bit binaries.
If an application is available for both 32-bit and 64-bit environments, installing both versions may cause problems. In such cases, decide on one version to install to avoid potential runtime errors.
An exception to this rule is PAM (pluggable authentication modules). openSUSE Leap uses PAM in the authentication process as a layer that mediates between user and application. Always install both PAM versions on 64-bit operating systems that also run 32-bit applications.
For correct execution, every application requires a range of libraries. Unfortunately, the names are identical for the 32-bit and 64-bit versions of these libraries. They must be differentiated from each other in another way.
To retain compatibility with 32-bit versions, 64-bit and
32-bit libraries are stored in the same location. The 32-bit
version of libc.so.6
is located under
/lib/libc.so.6
in both 32-bit and 64-bit
environments.
All 64-bit libraries and object files are located in directories called
lib64
. The 64-bit object files normally
found under /lib
and
/usr/lib
are now found under
/lib64
and /usr/lib64
. This means
that space is available for 32-bit libraries under /lib
and /usr/lib
, so the file name for both versions can
remain unchanged.
If the data content of 32-bit subdirectories under /lib
does not
depend on word size, they are not moved. This scheme conforms to LSB (Linux Standards Base)
and FHS (File System Hierarchy Standard).
The 64-bit kernels for AMD64/Intel 64 offer both a 64-bit and a 32-bit kernel ABI (application binary interface). The latter is identical to the ABI for the corresponding 32-bit kernel. This means that communication between both 32-bit and 64-bit applications with 64-bit kernels are identical.
The 32-bit system call emulation for 64-bit kernels does not support
all the APIs used by system programs. This depends on the platform. For this
reason, few applications, like lspci
, must be
compiled.
A 64-bit kernel can only load 64-bit kernel modules. You must compile 64-bit modules specifically for 64-bit kernels. It is not possible to use 32-bit kernel modules with 64-bit kernels.
Some applications require separate kernel-loadable modules. If you intend to use a 32-bit application in a 64-bit system environment, contact the provider of the application and SUSE. Make sure that the 64-bit version of the kernel-loadable module and the 32-bit compiled version of the kernel API are available for this module.
Booting a Linux system involves different components and tasks. After a
firmware and hardware initialization process, which depends on the
machine's architecture, the kernel is started by means of the boot loader
GRUB 2. After this point, the boot process is completely controlled by the
operating system and handled by systemd
. systemd
provides a set of
“targets” that boot configurations for everyday usage,
maintenance or emergencies.
This chapter uses terms that can be interpreted ambiguously. To understand how they are used here, read the definitions below:
init
Two different processes are commonly named “init”:
The initramfs
process mounting the root
file system
The operating system process that starts all other processes that is executed from the real root file system
In both cases, the systemd
program is taking care of this task. It is
first executed from the initramfs
to mount the
root file system. Once that has succeeded, it is re-executed from the
root file system as the initial process. To avoid confusing these two
systemd
processes, we refer to the first process as init on
initramfs and to the second one as
systemd.
initrd
/initramfs
An initrd
(initial RAM disk) is an image file
containing a root file system image which is loaded by the kernel and
mounted from /dev/ram
as the temporary root file
system. Mounting this file system requires a file system driver.
Beginning with kernel 2.6.13, the initrd has been replaced by the
initramfs
(initial RAM file system), which does
not require a file system driver to be mounted. openSUSE Leap exclusively
uses an initramfs
. However, since the
initramfs
is stored as
/boot/initrd
, it is often called
“initrd”. In this chapter we exclusively use the name
initramfs
.
The Linux boot process consists of several stages, each represented by a different component:
During the initialization phase the machine's hardware is set up and the devices are prepared. This process differs significantly between hardware architectures.
openSUSE Leap uses the boot loader GRUB 2 on all architectures. Depending on the architecture and firmware, starting the GRUB 2 boot loader can be a multi-step process. The purpose of the boot loader is to load the kernel and the initial, RAM-based file system (initramfs). For more information about GRUB 2, refer to Chapter 12, The Boot Loader GRUB 2.
After turning on the computer, the BIOS or the UEFI initializes the screen and keyboard, and tests the main memory. Up to this stage, the machine does not access any mass storage media. Subsequently, the information about the current date, time, and the most important peripherals are loaded from the CMOS values. When the boot media and its geometry are recognized, the system control passes from the BIOS/UEFI to the boot loader.
On a machine equipped with a traditional BIOS, only code from the first
physical 512-byte data sector (the Master Boot Record, MBR) of the boot
disk can be loaded. Only a minimal GRUB 2 fits into the MBR. Its sole
purpose is to load a GRUB 2 core image containing file system drivers from
the gap between the MBR and the first partition (MBR partition table) or
from the BIOS boot partition (GPT partition table). This image contains
file system drivers and therefore is able to access
/boot
located on the root file
system. /boot
contains additional modules for GRUB 2
core as well as the kernel and the initramfs image. Once it has access to
this partition, GRUB 2 loads the kernel and the initramfs image into
memory and hands control over to the kernel.
When booting a BIOS system from an encrypted file system that includes an
encrypted /boot
partition, you need to enter the
password for decryption twice. It is first needed by GRUB 2 to decrypt
/boot
and then for systemd
to mount the encrypted
volumes.
On machines with UEFI the boot process is much simpler than on machines
with a traditional BIOS. The firmware is able to read from a FAT formatted
system partition of disks with a GPT partition table. This EFI
system-partition (in the running system mounted as
/boot/efi
) holds enough space to host a fully-fledged
GRUB 2 which is directly loaded and executed by the firmware.
If the BIOS/UEFI supports network booting, it is also possible to configure a boot server that provides the boot loader. The system can then be booted via PXE. The BIOS/UEFI acts as the boot loader. It gets the boot image from the boot server and starts the system. This is completely independent of local hard disks.
When the boot loader has passed on system control, the boot process is the
same on all architectures. The boot loader loads both the kernel and an
initial RAM-based file system (initramfs
) into
memory and the kernel takes over.
After the kernel has set up memory management and has detected the CPU type
and its features, it initializes the hardware and mounts the temporary root
file system from the memory that was loaded with the
initramfs
.
initramfs
file #Edit source
initramfs
(initial RAM file system) is a small
cpio archive that the kernel can load into a RAM disk. It is located at
/boot/initrd
. It can be created with a tool called
dracut
—refer to man 8 dracut
for details.
The initramfs
provides a minimal Linux
environment that enables the execution of programs before the actual root
file system is mounted. This minimal Linux environment is loaded into
memory by BIOS or UEFI routines and does not have specific hardware
requirements other than sufficient memory. The
initramfs
archive must always provide an
executable named init
that executes the systemd
daemon on the root file system for the boot process to proceed.
Before the root file system can be mounted and the operating system can be
started, the kernel needs the corresponding drivers to access the device
on which the root file system is located. These drivers may include
special drivers for certain kinds of hard disks or even network drivers to
access a network file system. The needed modules for the root file system
are loaded by init
on
initramfs
. After the modules are loaded,
udev
provides the
initramfs
with the needed devices. Later in the
boot process, after changing the root file system, it is necessary to
regenerate the devices. This is done by the systemd
unit
systemd-udev-trigger.service
.
Because the initramfs
contains drivers, it needs
to be updated whenever a new version of one of its drivers is
available. This is done automatically when installing the package
containing the driver update. YaST or zypper will inform you about
this by showing the output of the command that generates the
initramfs
. However, there are some occasions
when you need to regenerate an initramfs
manually:
If you need to change hardware (for example, hard disks), and this
hardware requires different drivers to be in the kernel at boot time,
you must update the initramfs
file.
Open or create
/etc/dracut.conf.d/10-DRIVER.conf
and add the following line (mind the leading whitespace):
force_drivers+=" DRIVER1"
Replace DRIVER1 with the module name of the driver. If you need to add more than one driver, list them space-separated:
force_drivers+=" DRIVER1 DRIVER2"
Proceed with Procedure 9.1, “Generate an initramfs”.
Whenever you move swap files, or system directories like
/usr
in a running system to a RAID or logical
volume, you need to create an initramfs
that
contains support for software RAID or LVM drivers.
To do so, create the respective entries in
/etc/fstab
and mount the new entries (for example
with mount -a
and/or swapon -a
).
Proceed with Procedure 9.1, “Generate an initramfs”.
Whenever you add (or remove) a disk to a logical volume group
or a Btrfs RAID containing the root file system, you need to create an
initramfs
that contains support for the
enlarged volume. Follow the instructions at Procedure 9.1, “Generate an initramfs”.
Proceed with Procedure 9.1, “Generate an initramfs”.
If you change the values of kernel variables via the
sysctl
interface by editing related files
(/etc/sysctl.conf
or
/etc/sysctl.d/*.conf
), the change will be lost on
the next system reboot. Even if you load the values with sysctl
--system
at runtime, the changes are not saved into the
initramfs
file. You need to update it by
proceeding as outlined in Procedure 9.1, “Generate an initramfs”.
Note that all commands in the following procedure need to be executed as
user root
.
Generate a new initramfs
file by running
dracut MY_INITRAMFS
Replace MY_INITRAMFS with a file name of
your choice. The new initramfs
will be created
as /boot/MY_INITRAMFS
.
Alternatively, run dracut -f
. This will overwrite
the currently used, existing file.
(Skip this step if you ran dracut -f
in the previous
step.) Create a link to the initramfs
file you
created in the previous step:
(cd /boot && ln -sf MY_INITRAMFS initrd)
The temporary root file system mounted by the kernel from the
initramfs
contains the executable systemd
(which
is called init
on
initramfs
in the following, also see Section 9.1, “Terminology”. This program performs all actions needed
to mount the proper root file system. It provides kernel functionality for
the needed file system and device drivers for mass storage controllers with
udev
.
The main purpose of init
on
initramfs
is to prepare the mounting of and access
to the real root file system. Depending on your system configuration,
init
on initramfs
is
responsible for the following tasks.
Depending on your hardware configuration, special drivers may be needed to access the hardware components of your computer (the most important component being your hard disk). To access the final root file system, the kernel needs to load the proper file system drivers.
The kernel generates device events depending on loaded modules.
udev
handles these events and
generates the required special block files on a RAM file system in
/dev
. Without those special files, the file system
and other devices would not be accessible.
If you configured your system to hold the root file system under RAID or
LVM, init
on initramfs
sets up LVM or RAID to enable access to the root file system later.
If you configured your system to use a network-mounted root file system
(mounted via NFS), init
must make sure that the
proper network drivers are loaded and that they are set up to allow
access to the root file system.
If the file system resides on a network block device like iSCSI or SAN,
the connection to the storage server is also set up by
init
on initramfs
.
openSUSE Leap supports booting from a secondary iSCSI target if the
primary target is not available. .
If the root file system fails to mount from within the boot environment, it must be checked and repaired before the boot can continue. The file system checker will be automatically started for Ext3 and Ext4 file systems. The repair process is not automated for XFS and Btrfs file systems, and the user is presented with information describing the options available to repair the file system. When the file system has been successfully repaired, exiting the boot environment will cause the system to retry mounting the root file system. If successful, the boot will continue normally.
When init
on initramfs
is called during the initial boot as part of the installation process, its
tasks differ from those mentioned above. Note that the installation system
also does not start systemd
from
initramfs
—these tasks are performed by
linuxrc
.
When starting the installation process, your machine loads an
installation kernel and a special init
containing the YaST installer. The YaST installer is running in a
RAM file system and needs to have information about the location of the
installation medium to access it for installing the operating system.
As mentioned in Section 9.2.2.1, “The initramfs
file”, the boot process
starts with a minimum set of drivers that can be used with most
hardware configurations. On AArch64, POWER, and AMD64/Intel 64 machines,
linuxrc
starts an initial hardware scanning process
that determines the set of drivers suitable for your hardware
configuration. On IBM Z, a list of drivers and their parameters
needs to be provided, for example via linuxrc or a parmfile.
These drivers are used to generate a custom
initramfs
that is needed to boot the
system. If the modules are not needed for boot but for coldplug, the
modules can be loaded with systemd
; for more information, see Section 10.6.4, “Loading Kernel Modules”.
When the hardware is properly recognized, the appropriate drivers are
loaded. The udev
program
creates the special device files and linuxrc
starts the installation system with the YaST installer.
Finally, linuxrc
starts YaST, which starts
the package installation and the system configuration.
After the “real” root file system has been found, it is
checked for errors and mounted. If this is successful, the
initramfs
is cleaned and the systemd
daemon on
the root file system is executed. systemd
is Linux's system and service
manager. It is the parent process that is started as PID 1 and acts as an
init system which brings up and maintains user space services. See Chapter 10, The systemd
Daemon for details.
systemd
Daemon #Edit source
The program systemd
is the process with process ID 1. It is responsible for
initializing the system in the required way. systemd
is started directly by
the kernel and resists signal 9, which normally terminates processes.
All other programs are either started directly by systemd or by one of its
child processes.
Systemd is a replacement for the System V init daemon. systemd
is fully
compatible with System V init (by supporting init scripts). One of the main
advantages of systemd is that it considerably speeds up boot time by
aggressively paralleling service starts. Furthermore, systemd only starts a
service when it is really needed. Daemons are not started unconditionally at
boot time, but rather when being required for the first time. systemd also
supports Kernel Control Groups (cgroups), snapshotting and restoring the
system state and more. See http://www.freedesktop.org/wiki/Software/systemd/ for details.
This section will go into detail about the concept behind systemd.
systemd is a system and session manager for Linux, compatible with System V and LSB init scripts. The main features are:
provides aggressive parallelization capabilities
uses socket and D-Bus activation for starting services
offers on-demand starting of daemons
keeps track of processes using Linux cgroups
supports snapshotting and restoring of the system state
maintains mount and automount points
implements an elaborate transactional dependency-based service control logic
A unit configuration file contains information about a service, a socket, a device, a mount point, an automount point, a swap file or partition, a start-up target, a watched file system path, a timer controlled and supervised by systemd, a temporary system state snapshot, a resource management slice or a group of externally created processes. “Unit file” is a generic term used by systemd for the following:
Service. Information about a process (for example running a daemon); file ends with .service
Targets. Used for grouping units and as synchronization points during start-up; file ends with .target
Sockets.
Information about an IPC or network socket or a file system FIFO, for
socket-based activation (like
inetd
); file ends with .socket
Path. Used to trigger other units (for example running a service when files change); file ends with .path
Timer. Information about a timer controlled, for timer-based activation; file ends with .timer
Mount point. Usually auto-generated by the fstab generator; file ends with .mount
Automount point. Information about a file system automount point; file ends with .automount
Swap. Information about a swap device or file for memory paging; file ends with .swap
Device. Information about a device unit as exposed in the sysfs/udev(7) device tree; file ends with .device
Scope / Slice. A concept for hierarchically managing resources of a group of processes; file ends with .scope/.slice
For more information about systemd.unit see http://www.freedesktop.org/software/systemd/man/systemd.unit.html
The System V init system uses several commands to handle services—the
init scripts, insserv
, telinit
and
others. systemd makes it easier to manage services, since there is only one
command to memorize for the majority of service-handling tasks:
systemctl
. It uses the “command plus
subcommand” notation like git
or
zypper
:
systemctl GENERAL OPTIONS SUBCOMMAND SUBCOMMAND OPTIONS
See man 1 systemctl
for a complete manual.
If the output goes to a terminal (and not to a pipe or a file, for example)
systemd commands send long output to a pager by default. Use the
--no-pager
option to turn off paging mode.
systemd also supports bash-completion, allowing you to enter the first
letters of a subcommand and then press →| to
automatically complete it. This feature is only available in the
bash
shell and requires the installation of the
package bash-completion
.
Subcommands for managing services are the same as for managing a service
with System V init (start
, stop
,
...). The general syntax for service management commands is as follows:
systemctl reload|restart|start|status|stop|... MY_SERVICE(S)
rcMY_SERVICE(S) reload|restart|start|status|stop|...
systemd allows you to manage several services in one go. Instead of executing init scripts one after the other as with System V init, execute a command like the following:
tux >
sudo
systemctl start MY_1ST_SERVICE MY_2ND_SERVICE
To list all services available on the system:
tux >
sudo
systemctl list-unit-files --type=service
The following table lists the most important service management commands for systemd and System V init:
Task |
systemd Command |
System V init Command |
---|---|---|
Starting. |
start |
start |
Stopping. |
stop |
stop |
Restarting. Shuts down services and starts them afterward. If a service is not yet running it will be started. |
restart |
restart |
Restarting conditionally. Restarts services if they are currently running. Does nothing for services that are not running. |
try-restart |
try-restart |
Reloading.
Tells services to reload their configuration files without
interrupting operation. Use case: Tell Apache to reload a modified
|
reload |
reload |
Reloading or restarting. Reloads services if reloading is supported, otherwise restarts them. If a service is not yet running it will be started. |
reload-or-restart |
n/a |
Reloading or restarting conditionally. Reloads services if reloading is supported, otherwise restarts them if currently running. Does nothing for services that are not running. |
reload-or-try-restart |
n/a |
Getting detailed status information.
Lists information about the status of services. The |
status |
status |
Getting short status information. Shows whether services are active or not. |
is-active |
status |
The service management commands mentioned in the previous section let you manipulate services for the current session. systemd also lets you permanently enable or disable services, so they are automatically started when requested or are always unavailable. You can either do this by using YaST, or on the command line.
The following table lists enabling and disabling commands for systemd and System V init:
When enabling a service on the command line, it is not started
automatically. It is scheduled to be started with the next system
start-up or runlevel/target change. To immediately start a service after
having enabled it, explicitly run systemctl start
MY_SERVICE
or rc
MY_SERVICE start
.
Task |
|
System V init Command |
---|---|---|
Enabling. |
|
|
Disabling. |
|
|
Checking. Shows whether a service is enabled or not. |
|
|
Re-enabling. Similar to restarting a service, this command first disables and then enables a service. Useful to re-enable a service with its defaults. |
|
n/a |
Masking. After “disabling” a service, it can still be started manually. To completely disable a service, you need to mask it. Use with care. |
|
n/a |
Unmasking. A service that has been masked can only be used again after it has been unmasked. |
|
n/a |
The entire process of starting the system and shutting it down is maintained by systemd. From this point of view, the kernel can be considered a background process to maintain all other processes and adjust CPU time and hardware access according to requests from other programs.
With System V init the system was booted into a so-called
“Runlevel”. A runlevel defines how the system is started and
what services are available in the running system. Runlevels are numbered;
the most commonly known ones are 0
(shutting down the
system), 3
(multiuser with network) and
5
(multiuser with network and display manager).
systemd introduces a new concept by using so-called “target
units”. However, it remains fully compatible with the runlevel
concept. Target units are named rather than numbered and serve specific
purposes. For example, the targets local-fs.target
and swap.target
mount local file systems and swap
spaces.
The target graphical.target
provides a multiuser
system with network and display manager capabilities and is equivalent to
runlevel 5. Complex targets, such as
graphical.target
act as “meta”
targets by combining a subset of other targets. Since systemd makes it easy
to create custom targets by combining existing targets, it offers great
flexibility.
The following list shows the most important systemd target units. For a
full list refer to man 7 systemd.special
.
default.target
The target that is booted by default. Not a “real” target,
but rather a symbolic link to another target like
graphic.target
. Can be permanently changed via
YaST (see Section 10.4, “Managing Services with YaST”). To change it for
a session, use the kernel parameter
systemd.unit=MY_TARGET.target
at the boot prompt.
emergency.target
Starts an emergency shell on the console. Only use it at the boot prompt
as systemd.unit=emergency.target
.
graphical.target
Starts a system with network, multiuser support and a display manager.
halt.target
Shuts down the system.
mail-transfer-agent.target
Starts all services necessary for sending and receiving mails.
multi-user.target
Starts a multiuser system with network.
reboot.target
Reboots the system.
rescue.target
Starts a single-user system without network.
To remain compatible with the System V init runlevel system, systemd
provides special targets named
runlevelX.target
mapping the
corresponding runlevels numbered X.
If you want to know the current target, use the command: systemctl
get-default
systemd
Target Units #
System V runlevel |
|
Purpose |
---|---|---|
0 |
|
System shutdown |
1, S |
|
Single-user mode |
2 |
|
Local multiuser without remote network |
3 |
|
Full multiuser with network |
4 |
|
Unused/User-defined |
5 |
|
Full multiuser with network and display manager |
6 |
|
System reboot |
/etc/inittab
The runlevels in a System V init system are configured in
/etc/inittab
. systemd does not
use this configuration. Refer to
Section 10.5.3, “Creating Custom Targets” for instructions on how
to create your own bootable target.
Use the following commands to operate with target units:
Task |
systemd Command |
System V init Command |
---|---|---|
Change the current target/runlevel |
|
|
Change to the default target/runlevel |
|
n/a |
Get the current target/runlevel |
With systemd there is usually more than one active target. The command lists all currently active targets. |
or
|
persistently change the default runlevel |
Use the Services Manager or run the following command:
|
Use the Services Manager or change the line
in |
Change the default runlevel for the current boot process |
Enter the following option at the boot prompt
|
Enter the desired runlevel number at the boot prompt. |
Show a target's/runlevel's dependencies |
“Requires” lists the hard dependencies (the ones that must be resolved), whereas “Wants” lists the soft dependencies (the ones that get resolved if possible). |
n/a |
systemd offers the means to analyze the system start-up process. You can
review the list of all services and their status (rather than having to
parse /var/log/
). systemd also allows you to scan the
start-up procedure to find out how much time each service start-up
consumes.
To review the complete list of services that have been started since
booting the system, enter the command systemctl
. It
lists all active services like shown below (shortened). To get more
information on a specific service, use systemctl status
MY_SERVICE
.
root #
systemctl
UNIT LOAD ACTIVE SUB JOB DESCRIPTION
[...]
iscsi.service loaded active exited Login and scanning of iSC+
kmod-static-nodes.service loaded active exited Create list of required s+
libvirtd.service loaded active running Virtualization daemon
nscd.service loaded active running Name Service Cache Daemon
chronyd.service loaded active running NTP Server Daemon
polkit.service loaded active running Authorization Manager
postfix.service loaded active running Postfix Mail Transport Ag+
rc-local.service loaded active exited /etc/init.d/boot.local Co+
rsyslog.service loaded active running System Logging Service
[...]
LOAD = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB = The low-level unit activation state, values depend on unit type.
161 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.
To restrict the output to services that failed to start, use the
--failed
option:
root #
systemctl --failed
UNIT LOAD ACTIVE SUB JOB DESCRIPTION
apache2.service loaded failed failed apache
NetworkManager.service loaded failed failed Network Manager
plymouth-start.service loaded failed failed Show Plymouth Boot Screen
[...]
To debug system start-up time, systemd offers the
systemd-analyze
command. It shows the total start-up
time, a list of services ordered by start-up time and can also generate an
SVG graphic showing the time services took to start in relation to the
other services.
root #
systemd-analyze
Startup finished in 2666ms (kernel) + 21961ms (userspace) = 24628ms
root #
systemd-analyze blame
15.000s backup-rpmdb.service
14.879s mandb.service
7.646s backup-sysconfig.service
4.940s postfix.service
4.921s logrotate.service
4.640s libvirtd.service
4.519s display-manager.service
3.921s btrfsmaintenance-refresh.service
3.466s lvm2-monitor.service
2.774s plymouth-quit-wait.service
2.591s firewalld.service
2.137s initrd-switch-root.service
1.954s ModemManager.service
1.528s rsyslog.service
1.378s apparmor.service
[...]
root #
systemd-analyze plot > jupiter.example.com-startup.svg
The above-mentioned commands let you review the services that started and
the time it took to start them. If you need to know more details, you can
tell systemd
to verbosely log the complete start-up procedure by
entering the following parameters at the boot prompt:
systemd.log_level=debug systemd.log_target=kmsg
Now systemd
writes its log messages into the kernel ring buffer. View
that buffer with dmesg
:
tux >
dmesg -T | less
systemd is compatible with System V, allowing you to still use existing
System V init scripts. However, there is at least one known issue where a
System V init script does not work with systemd out of the box: starting a
service as a different user via su
or
sudo
in init scripts will result in a failure of the
script, producing an “Access denied” error.
When changing the user with su
or
sudo
, a PAM session is started. This session will be
terminated after the init script is finished. As a consequence, the service
that has been started by the init script will also be terminated. To work
around this error, proceed as follows:
Create a service file wrapper with the same name as the init script plus
the file name extension .service
:
[Unit] Description=DESCRIPTION After=network.target [Service] User=USER Type=forking1 PIDFile=PATH TO PID FILE1 ExecStart=PATH TO INIT SCRIPT start ExecStop=PATH TO INIT SCRIPT stop ExecStopPost=/usr/bin/rm -f PATH TO PID FILE1 [Install] WantedBy=multi-user.target2
Replace all values written in UPPERCASE LETTERS with appropriate values.
Start the daemon with systemctl start
APPLICATION
.
Basic service management can also be done with the YaST Services Manager module. It supports starting, stopping, enabling and disabling services. It also lets you show a service's status and change the default target. Start the YaST module with
› › .To change the target the system boots into, choose a target from the
drop-down box. The most often used targets are (starting a graphical login screen) and (starting the system in command line mode).Select a service from the table. The
column shows whether it is currently running ( ) or not ( ). Toggle its status by choosing .Starting or stopping a service changes its status for the currently running session. To change its status throughout a reboot, you need to enable or disable it.
Select a service from the table. The
column shows whether it is currently or . Toggle its status by choosing .By enabling or disabling a service you configure whether it is started during booting (
) or not ( ). This setting will not affect the current session. To change its status in the current session, you need to start or stop it.
To view the status message of a service, select it from the list and
choose systemctl
-l
status
MY_SERVICE.
Faulty runlevel settings may make your system unusable. Before applying your changes, make absolutely sure that you know their consequences.
systemd
#Edit source
The following sections contain some examples for
systemd
customization.
When customizing systemd, always use the directory
/etc/systemd/
,
never use /usr/lib/systemd/
.
Otherwise your changes will be overwritten by the next update of systemd.
The recommended way to customize unit files is to use the
systemctl edit SERVICE
command. This command starts the default text editor and creates a
directory with the override.conf
file in
/etc/systemd/system/NAME.service.d/
. The
command also ensures that the running systemd process is notified
about the changes.
Alternatively, you can open a copy of the original
file for editing instead of a blank file by running
systemctl edit --full SERVICE
.
When editing the file, make sure that you do not remove any of the
existing sections.
As an exercise, change how long the system waits for MariaDB to start.
As root, run systemctl edit --full mariadb.service
.
The file opened will look similar to the following:
[Unit] Description=MySQL server Wants=basic.target Conflicts=mariadb.target After=basic.target network.target [Install] WantedBy=multi-user.target Alias=mysql.service [Service] Restart=on-abort Type=notify ExecStartPre=/usr/lib/mysql/mysql-systemd-helper install ExecStartPre=/usr/lib/mysql/mysql-systemd-helper upgrade ExecStart=/usr/lib/mysql/mysql-systemd-helper start # Configures the time to wait for start-up/stop TimeoutSec=300 # Prevent writes to /usr, /boot, and /etc ProtectSystem=full # Prevent accessing /home, /root and /run/user ProtectHome=true UMask=007
Adjust the TimeoutSec
value and save the
changes. To enable the changes, as root, run
systemctl daemon-reload
.
For further information, refer to the man pages that can be
evoked with the man 1 systemctl
command.
xinetd
Services to systemd
#Edit source
Since the release of openSUSE Leap 15, the xinetd
infrastructure has been removed. This section outlines how to convert
existing custom xinetd
service files to systemd
sockets.
For each xinetd
service file, you need at least
two systemd
unit files: the socket file (*.socket
)
and an associated service file (*.service
). The
socket file tells systemd
which socket to create, and the service file
tells systemd
which executable to start.
Consider the following example xinetd
service
file:
root #
cat /etc/xinetd.d/example
service example
{
socket_type = stream
protocol = tcp
port = 10085
wait = no
user = user
group = users
groups = yes
server = /usr/libexec/example/exampled
server_args = -auth=bsdtcp exampledump
disable = no
}
To convert it to systemd
, you need the following two matching files:
root #
cat /usr/lib/systemd/system/example.socket
[Socket]
ListenStream=0.0.0.0:10085
Accept=false
[Install]
WantedBy=sockets.target
root #
cat /usr/lib/systemd/system/example.service
[Unit]
Description=example
[Service]
ExecStart=/usr/libexec/example/exampled -auth=bsdtcp exampledump
User=user
Group=users
StandardInput=socket
For a complete list of the systemd
'socket' and 'service' file options,
refer to the systemd.socket and systemd.service manual pages (man
5 systemd.socket
, man 5 systemd.service
).
If you only want to add a few lines to a configuration file or modify a small part of it, you can use so-called “drop-in” files. Drop-in files let you extend the configuration of unit files without having to edit or override the unit files themselves.
For example, to change one value for the FOOBAR
service located in
/usr/lib/systemd/system/FOOBAR.SERVICE
,
proceed as follows:
Create a directory called
/etc/systemd/system/FOOBAR.service.d/
.
Note the .d
suffix. The directory must otherwise be
named like the service that you want to patch with the drop-in file.
In that directory, create a file
WHATEVERMODIFICATION.conf
.
Make sure it only contains the line with the value that you want to modify.
Save your changes to the file. It will be used as an extension of the original file.
On System V init SUSE systems, runlevel 4 is unused to allow
administrators to create their own runlevel configuration. systemd allows
you to create any number of custom targets. It is suggested to start by
adapting an existing target such as
graphical.target
.
Copy the configuration file
/usr/lib/systemd/system/graphical.target
to
/etc/systemd/system/MY_TARGET.target
and adjust it according to your needs.
The configuration file copied in the previous step already covers the
required (“hard”) dependencies for the target. To also cover
the wanted (“soft”) dependencies, create a directory
/etc/systemd/system/MY_TARGET.target.wants
.
For each wanted service, create a symbolic link from
/usr/lib/systemd/system
into
/etc/systemd/system/MY_TARGET.target.wants
.
When you have finished setting up the target, reload the systemd configuration to make the new target available:
tux >
sudo
systemctl daemon-reload
The following sections cover advanced topics for system administrators. For even more advanced systemd documentation, refer to Lennart Pöttering's series about systemd for administrators at http://0pointer.de/blog/projects.
systemd
supports cleaning temporary directories regularly. The
configuration from the previous system version is automatically migrated
and active. tmpfiles.d
—which is responsible for
managing temporary files—reads its configuration from
/etc/tmpfiles.d/*.conf
,
/run/tmpfiles.d/*.conf
, and
/usr/lib/tmpfiles.d/*.conf
files. Configuration placed
in /etc/tmpfiles.d/*.conf
overrides related
configurations from the other two directories
(/usr/lib/tmpfiles.d/*.conf
is where packages store
their configuration files).
The configuration format is one line per path containing action and path, and optionally mode, ownership, age and argument fields, depending on the action. The following example unlinks the X11 lock files:
Type Path Mode UID GID Age Argument r /tmp/.X[0-9]*-lock
To get the status the tmpfile timer:
tux >
sudo
systemctl status systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.timer - Daily Cleanup of Temporary Directories Loaded: loaded (/usr/lib/systemd/system/systemd-tmpfiles-clean.timer; static) Active: active (waiting) since Tue 2018-04-09 15:30:36 CEST; 1 weeks 6 days ago Docs: man:tmpfiles.d(5) man:systemd-tmpfiles(8) Apr 09 15:30:36 jupiter systemd[1]: Starting Daily Cleanup of Temporary Directories. Apr 09 15:30:36 jupiter systemd[1]: Started Daily Cleanup of Temporary Directories.
For more information on temporary files handling, see man 5
tmpfiles.d
.
Section 10.6.9, “Debugging Services” explains how
to view log messages for a given service. However, displaying log messages
is not restricted to service logs. You can also access and query the
complete log messages written by systemd
—the so-called
“Journal”. Use the command
journalctl
to display the complete log messages
starting with the oldest entries. Refer to man 1
journalctl
for options such as applying filters or
changing the output format.
You can save the current state of systemd
to a named snapshot and later
revert to it with the isolate
subcommand. This is useful
when testing services or custom targets, because it allows you to return to
a defined state at any time. A snapshot is only available in the current
session and will automatically be deleted on reboot. A snapshot name must
end in .snapshot
.
tux >
sudo
systemctl snapshot MY_SNAPSHOT.snapshot
tux >
sudo
systemctl delete MY_SNAPSHOT.snapshot
tux >
sudo
systemctl show MY_SNAPSHOT.snapshot
tux >
sudo
systemctl isolate MY_SNAPSHOT.snapshot
With systemd
, kernel modules can automatically be loaded at boot time via
a configuration file in /etc/modules-load.d
. The file
should be named MODULE.conf and have the
following content:
# load module MODULE at boot time MODULE
In case a package installs a configuration file for loading a kernel
module, the file gets installed to
/usr/lib/modules-load.d
. If two configuration files
with the same name exist, the one in
/etc/modules-load.d
tales precedence.
For more information, see the modules-load.d(5)
man page.
With System V init actions that need to be performed before loading a
service, needed to be specified in /etc/init.d/before.local
. This procedure is no longer supported with systemd. If you
need to do actions before starting services, do the following:
Create a drop-in file in /etc/modules-load.d
directory (see man modules-load.d
for the syntax)
Create a drop-in file in /etc/tmpfiles.d
(see
man tmpfiles.d
for the syntax)
Create a system service file, for example
/etc/systemd/system/before.service
, from the
following template:
[Unit] Before=NAME OF THE SERVICE YOU WANT THIS SERVICE TO BE STARTED BEFORE [Service] Type=oneshot RemainAfterExit=true ExecStart=YOUR_COMMAND # beware, executable is run directly, not through a shell, check the man pages # systemd.service and systemd.unit for full syntax [Install] # target in which to start the service WantedBy=multi-user.target #WantedBy=graphical.target
When the service file is created, you should run the following commands
(as root
):
tux >
sudo
systemctl daemon-reloadtux >
sudo
systemctl enable before
Every time you modify the service file, you need to run:
tux >
sudo
systemctl daemon-reload
On a traditional System V init system it is not always possible to clearly assign a process to the service that spawned it. Some services, such as Apache, spawn a lot of third-party processes (for example CGI or Java processes), which themselves spawn more processes. This makes a clear assignment difficult or even impossible. Additionally, a service may not terminate correctly, leaving some children alive.
systemd solves this problem by placing each service into its own cgroup. cgroups are a kernel feature that allows aggregating processes and all their children into hierarchical organized groups. systemd names each cgroup after its service. Since a non-privileged process is not allowed to “leave” its cgroup, this provides an effective way to label all processes spawned by a service with the name of the service.
To list all processes belonging to a service, use the command
systemd-cgls
. The result will look like the following
(shortened) example:
root #
systemd-cgls --no-pager
├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 20
├─user.slice
│ └─user-1000.slice
│ ├─session-102.scope
│ │ ├─12426 gdm-session-worker [pam/gdm-password]
│ │ ├─15831 gdm-session-worker [pam/gdm-password]
│ │ ├─15839 gdm-session-worker [pam/gdm-password]
│ │ ├─15858 /usr/lib/gnome-terminal-server
[...]
└─system.slice
├─systemd-hostnamed.service
│ └─17616 /usr/lib/systemd/systemd-hostnamed
├─cron.service
│ └─1689 /usr/sbin/cron -n
├─postfix.service
│ ├─ 1676 /usr/lib/postfix/master -w
│ ├─ 1679 qmgr -l -t fifo -u
│ └─15590 pickup -l -t fifo -u
├─sshd.service
│ └─1436 /usr/sbin/sshd -D
[...]
See Book “System Analysis and Tuning Guide”, Chapter 9 “Kernel Control Groups” for more information about cgroups.
As explained in Section 10.6.6, “Kernel Control Groups (cgroups)”, it is not always possible to assign a process to its parent service process in a System V init system. This makes it difficult to terminate a service and all of its children. Child processes that have not been terminated will remain as zombie processes.
systemd's concept of confining each service into a cgroup makes it possible
to clearly identify all child processes of a service and therefore allows
you to send a signal to each of these processes. Use systemctl
kill
to send signals to services. For a list of available signals
refer to man 7 signals
.
SIGTERM
to a Service
SIGTERM
is the default signal that is sent.
tux >
sudo
systemctl kill MY_SERVICE
Use the -s
option to specify the signal that should be
sent.
tux >
sudo
systemctl kill -s SIGNAL MY_SERVICE
By default the kill
command sends the signal to
all
processes of the specified cgroup. You can restrict
it to the control
or the main
process.
The latter is for example useful to force a service to reload its
configuration by sending SIGHUP
:
tux >
sudo
systemctl kill -s SIGHUP --kill-who=main MY_SERVICE
The D-Bus service is the message bus for communication between systemd
clients and the systemd manager that is running as pid 1. Even though
dbus
is a stand-alone daemon, it
is an integral part of the init infrastructure.
Terminating dbus
or restarting it
in the running system is similar to an attempt to terminate or restart pid
1. It will break systemd client/server communication and make most systemd
functions unusable.
Therefore, terminating or restarting
dbus
is neither recommended
nor supported.
Updating the dbus
or
dbus
-related packages requires a reboot. When in
doubt whether a reboot is necessary, run the sudo zypper ps
-s
. If dbus
appears among the listed
services, you need to reboot the system.
Keep in mind that dbus
is updated even when
automatic updates are configured to skip the packages that require reboot.
By default, systemd is not overly verbose. If a service was started
successfully, no output will be produced. In case of a failure, a short
error message will be displayed. However, systemctl
status
provides means to debug start-up and operation of a
service.
systemd comes with its own logging mechanism (“The Journal”)
that logs system messages. This allows you to display the service messages
together with status messages. The status
command works
similar to tail
and can also display the log messages in
different formats, making it a powerful debugging tool.
Whenever a service fails to start, use systemctl status
MY_SERVICE
to get a detailed error
message:
root #
systemctl start apache2 Job failed. See system journal and 'systemctl status' for details.root #
systemctl status apache2 Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: failed (Result: exit-code) since Mon, 04 Apr 2018 16:52:26 +0200; 29s ago Process: 3088 ExecStart=/usr/sbin/start_apache2 -D SYSTEMD -k start (code=exited, status=1/FAILURE) CGroup: name=systemd:/system/apache2.service Apr 04 16:52:26 g144 start_apache2[3088]: httpd2-prefork: Syntax error on line 205 of /etc/apache2/httpd.conf: Syntax error on li...alHost>
The default behavior of the status
subcommand is to
display the last ten messages a service issued. To change the number of
messages to show, use the
--lines=N
parameter:
tux >
sudo
systemctl status chronydtux >
sudo
systemctl --lines=20 status chronyd
To display a “live stream” of service messages, use the
--follow
option, which works like
tail
-f
:
tux >
sudo
systemctl --follow status chronyd
The --output=MODE
parameter
allows you to change the output format of service messages. The most
important modes available are:
short
The default format. Shows the log messages with a human readable time stamp.
verbose
Full output with all fields.
cat
Terse output without time stamps.
For more information on systemd refer to the following online resources:
Lennart Pöttering, one of the systemd authors, has written a series of blog entries (13 at the time of writing this chapter). Find them at http://0pointer.de/blog/projects.
journalctl
: Query the systemd
Journal #Edit source
When systemd
replaced traditional init scripts in openSUSE Leap
(see Chapter 10, The systemd
Daemon), it introduced its own logging system
called journal. There is no need to run a
syslog
based service anymore, as all system events
are written in the journal.
The journal itself is a system service managed by systemd
. Its full name is
systemd-journald.service
. It collects and stores logging
data by maintaining structured indexed journals based on logging information
received from the kernel, user processes, standard input, and system service errors. The systemd-journald
service is on
by default:
tux >
sudo
systemctl status systemd-journald systemd-journald.service - Journal Service Loaded: loaded (/usr/lib/systemd/system/systemd-journald.service; static) Active: active (running) since Mon 2014-05-26 08:36:59 EDT; 3 days ago Docs: man:systemd-journald.service(8) man:journald.conf(5) Main PID: 413 (systemd-journal) Status: "Processing requests..." CGroup: /system.slice/systemd-journald.service └─413 /usr/lib/systemd/systemd-journald [...]
The journal stores log data in /run/log/journal/
by
default. Because the /run/
directory is volatile by
nature, log data is lost at reboot. To make the log data persistent, the
directory /var/log/journal/
must exist with correct
ownership and permissions so the systemd-journald service can store its
data. systemd
will create the directory for you—and switch to
persistent logging—if you do the following:
As root
, open /etc/systemd/journald.conf
for
editing.
root #
vi /etc/systemd/journald.conf
Uncomment the line containing Storage=
and change it to
[...] [Journal] Storage=persistent #Compress=yes [...]
Save the file and restart systemd-journald:
root #
systemctl restart systemd-journald
journalctl
Useful Switches #Edit source
This section introduces several common useful options to enhance the default
journalctl
behavior. All switches are described in the
journalctl
manual page, man 1
journalctl
.
To show all journal messages related to a specific executable, specify the full path to the executable:
tux >
sudo
journalctl /usr/lib/systemd/systemd
Shows only the most recent journal messages, and prints new log entries as they are added to the journal.
Prints the messages and jumps to the end of the journal, so that the latest entries are visible within the pager.
Prints the messages of the journal in reverse order, so that the latest entries are listed first.
Shows only kernel messages. This is equivalent to the field match
_TRANSPORT=kernel
(see
Section 11.3.3, “Filtering Based on Fields”).
Shows only messages for the specified systemd
unit. This is equivalent
to the field match
_SYSTEMD_UNIT=UNIT
(see
Section 11.3.3, “Filtering Based on Fields”).
tux >
sudo
journalctl -u apache2 [...] Jun 03 10:07:11 pinkiepie systemd[1]: Starting The Apache Webserver... Jun 03 10:07:12 pinkiepie systemd[1]: Started The Apache Webserver.
When called without switches, journalctl
shows the full
content of the journal, the oldest entries listed first. The output can be
filtered by specific switches and fields.
journalctl
can filter messages based on a specific
system boot. To list all available boots, run
tux >
sudo
journalctl --list-boots -1 097ed2cd99124a2391d2cffab1b566f0 Mon 2014-05-26 08:36:56 EDT—Fri 2014-05-30 05:33:44 EDT 0 156019a44a774a0bb0148a92df4af81b Fri 2014-05-30 05:34:09 EDT—Fri 2014-05-30 06:15:01 EDT
The first column lists the boot offset: 0
for the
current boot, -1
for the previous one,
-2
for the one prior to that, etc. The second column
contains the boot ID followed by the limiting time stamps of the specific
boot.
Show all messages from the current boot:
tux >
sudo
journalctl -b
If you need to see journal messages from the previous boot, add an offset parameter. The following example outputs the previous boot messages:
tux >
sudo
journalctl -b -1
Another way is to list boot messages based on the boot ID. For this purpose, use the _BOOT_ID field:
tux >
sudo
journalctl _BOOT_ID=156019a44a774a0bb0148a92df4af81b
You can filter the output of journalctl
by specifying
the starting and/or ending date. The date specification should be of the
format "2014-06-30 9:17:16". If the time part is omitted, midnight is
assumed. If seconds are omitted, ":00" is assumed. If the date part is
omitted, the current day is assumed. Instead of numeric expression, you can
specify the keywords "yesterday", "today", or "tomorrow". They refer to
midnight of the day before the current day, of the current day, or of the
day after the current day. If you specify "now", it refers to the current
time. You can also specify relative times prefixed with
-
or +
, referring to times before or
after the current time.
Show only new messages since now, and update the output continuously:
tux >
sudo
journalctl --since "now" -f
Show all messages since last midnight till 3:20am:
tux >
sudo
journalctl --since "today" --until "3:20"
You can filter the output of the journal by specific fields. The syntax of
a field to be matched is FIELD_NAME=MATCHED_VALUE
, such
as _SYSTEMD_UNIT=httpd.service
. You can specify multiple
matches in a single query to filter the output messages even more. See
man 7 systemd.journal-fields
for a list of default
fields.
Show messages produced by a specific process ID:
tux >
sudo
journalctl _PID=1039
Show messages belonging to a specific user ID:
# journalctl _UID=1000
Show messages from the kernel ring buffer (the same as
dmesg
produces):
tux >
sudo
journalctl _TRANSPORT=kernel
Show messages from the service's standard or error output:
tux >
sudo
journalctl _TRANSPORT=stdout
Show messages produced by a specified service only:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service
If two different fields are specified, only entries that match both expressions at the same time are shown:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=1488
If two matches refer to the same field, all entries matching either expression are shown:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service
You can use the '+' separator to combine two expressions in a logical 'OR'. The following example shows all messages from the Avahi service process with the process ID 1480 together with all messages from the D-Bus service:
tux >
sudo
journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=1480 + _SYSTEMD_UNIT=dbus.service
systemd
Errors #Edit source
This section introduces a simple example to illustrate how to find and fix
the error reported by systemd
during apache2
start-up.
Try to start the apache2 service:
# systemctl start apache2 Job for apache2.service failed. See 'systemctl status apache2' and 'journalctl -xn' for details.
Let us see what the service's status says:
tux >
sudo
systemctl status apache2 apache2.service - The Apache Webserver Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: failed (Result: exit-code) since Tue 2014-06-03 11:08:13 CEST; 7min ago Process: 11026 ExecStop=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND \ -k graceful-stop (code=exited, status=1/FAILURE)
The ID of the process causing the failure is 11026.
Show the verbose version of messages related to process ID 11026:
tux >
sudo
journalctl -o verbose _PID=11026 [...] MESSAGE=AH00526: Syntax error on line 6 of /etc/apache2/default-server.conf: [...] MESSAGE=Invalid command 'DocumenttRoot', perhaps misspelled or defined by a module [...]
Fix the typo inside /etc/apache2/default-server.conf
,
start the apache2 service, and print its status:
tux >
sudo
systemctl start apache2 && systemctl status apache2 apache2.service - The Apache Webserver Loaded: loaded (/usr/lib/systemd/system/apache2.service; disabled) Active: active (running) since Tue 2014-06-03 11:26:24 CEST; 4ms ago Process: 11026 ExecStop=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND -k graceful-stop (code=exited, status=1/FAILURE) Main PID: 11263 (httpd2-prefork) Status: "Processing requests..." CGroup: /system.slice/apache2.service ├─11263 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11280 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11281 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11282 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] ├─11283 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...] └─11285 /usr/sbin/httpd2-prefork -f /etc/apache2/httpd.conf -D [...]
The behavior of the systemd-journald service can be adjusted by modifying
/etc/systemd/journald.conf
. This section introduces
only basic option settings. For a complete file description, see
man 5 journald.conf
. Note that you need to restart the
journal for the changes to take effect with
tux >
sudo
systemctl restart systemd-journald
If the journal log data is saved to a persistent location (see
Section 11.1, “Making the Journal Persistent”), it uses up to 10% of the file
system the /var/log/journal
resides on. For example,
if /var/log/journal
is located on a 30 GB
/var
partition, the journal may use up to 3 GB of the
disk space. To change this limit, change (and uncomment) the
SystemMaxUse
option:
SystemMaxUse=50M
/dev/ttyX
#Edit source
You can forward the journal to a terminal device to inform you about system
messages on a preferred terminal screen, for example
/dev/tty12
. Change the following journald options to
ForwardToConsole=yes TTYPath=/dev/tty12
Journald is backward compatible with traditional syslog implementations
such as rsyslog
. Make sure the following is valid:
rsyslog is installed.
tux >
sudo
rpm -q rsyslog rsyslog-7.4.8-2.16.x86_64
rsyslog service is enabled.
tux >
sudo
systemctl is-enabled rsyslog enabled
Forwarding to syslog is enabled in
/etc/systemd/journald.conf
.
ForwardToSyslog=yes
systemd
Journal #Edit source
For an easy way of filtering the systemd journal (without dealing
with the journalctl syntax), you can use the YaST journal module. After
installing it with sudo zypper in yast2-journal
, start it
from YaST by selecting › . Alternatively, start it
from command line by entering sudo yast2 journal
.
The module displays the log entries in a table. The search box on top allows
you to search for entries that contain certain characters, similar to using
grep
. To filter the entries by date and time, unit, file,
or priority, click and set the respective
options.
You can view the journal with GNOME Logs.
Start it from the application menu. To view system log messages, it
needs to be run as root, for example with xdg-su
gnome-logs
. This command can be executed when pressing
Alt–F2.
This chapter describes how to configure GRUB 2, the boot loader used in openSUSE® Leap. It is the successor to the traditional GRUB boot loader—now called “GRUB Legacy”. A YaST module is available for configuring the most important settings. The boot procedure as a whole is outlined in Chapter 9, Introduction to the Boot Process. For details on Secure Boot support for UEFI machines, see Chapter 14, UEFI (Unified Extensible Firmware Interface).
The configuration is stored in different files.
More file systems are supported (for example, Btrfs).
Can directly read files stored on LVM or RAID devices.
The user interface can be translated and altered with themes.
Includes a mechanism for loading modules to support additional features, such as file systems, etc.
Automatically searches for and generates boot entries for other kernels and operating systems, such as Windows.
Includes a minimal Bash-like console.
The configuration of GRUB 2 is based on the following files:
/boot/grub2/grub.cfg
This file contains the configuration of the GRUB 2 menu items. It
replaces menu.lst
used in GRUB Legacy.
grub.cfg
should not be edited—it is automatically
generated by the command grub2-mkconfig -o /boot/grub2/grub.cfg
.
/boot/grub2/custom.cfg
This optional file is directly sourced by grub.cfg
at boot time and can be used to add custom items to the boot menu.
Starting with openSUSE Leap Leap 42.2 these entries will also
be parsed when using grub-once
.
/etc/default/grub
This file controls the user settings of GRUB 2 and usually includes additional environmental settings such as backgrounds and themes.
/etc/grub.d/
The scripts in this directory are read during execution of the command
grub2-mkconfig -o /boot/grub2/grub.cfg
. Their instructions are
integrated into the main configuration file
/boot/grub/grub.cfg
.
/etc/sysconfig/bootloader
This configuration file holds some basic settings like the boot loader type and whether to enable UEFI Secure Boot support.
/boot/grub2/x86_64-efi
,
These configuration files contain architecture-specific options.
GRUB 2 can be controlled in various ways. Boot entries from an existing
configuration can be selected from the graphical menu (splash screen). The
configuration is loaded from the file
/boot/grub2/grub.cfg
which is compiled from other
configuration files (see below). All GRUB 2 configuration files are
considered system files, and you need root
privileges to edit them.
After having manually edited GRUB 2 configuration files, you need to run
grub2-mkconfig -o /boot/grub2/grub.cfg
to activate the changes. However, this
is not necessary when changing the configuration with YaST, because YaST will
automatically run this command.
/boot/grub2/grub.cfg
#Edit source
The graphical splash screen with the boot menu is based on the GRUB 2
configuration file /boot/grub2/grub.cfg
, which
contains information about all partitions or operating systems that can be
booted by the menu.
Every time the system is booted, GRUB 2 loads the menu file directly from
the file system. For this reason, GRUB 2 does not need to be re-installed
after changes to the configuration file. grub.cfg
is
automatically rebuilt with kernel installations or removals.
grub.cfg
is compiled from the file
/etc/default/grub
and scripts found in the
/etc/grub.d/
directory when running the command
grub2-mkconfig -o /boot/grub2/grub.cfg
. Therefore you should never
edit the file manually. Instead, edit the related source files or use the
YaST module to modify the configuration as
described in Section 12.3, “Configuring the Boot Loader with YaST”.
/etc/default/grub
#Edit sourceMore general options of GRUB 2 belong here, such as the time the menu is displayed, or the default OS to boot. To list all available options, see the output of the following command:
tux >
grep "export GRUB_DEFAULT" -A50 /usr/sbin/grub2-mkconfig | grep GRUB_
In addition to already defined variables, the user may introduce their own
variables, and use them later in the scripts found in the
/etc/grub.d
directory.
After having edited /etc/default/grub
, update the main
configuration file with grub2-mkconfig -o /boot/grub2/grub.cfg
.
All options set in this file are general options that affect all boot entries. Specific options for Xen kernels or the Xen hypervisor can be set via the GRUB_*_XEN_* configuration options. See below for details.
GRUB_DEFAULT
Sets the boot menu entry that is booted by default. Its value can be a numeric value, the complete name of a menu entry, or “saved”.
GRUB_DEFAULT=2
boots the third (counted from zero)
boot menu entry.
GRUB_DEFAULT="2>0"
boots the first submenu entry
of the third top-level menu entry.
GRUB_DEFAULT="Example boot menu entry"
boots the menu
entry with the title “Example boot menu entry”.
GRUB_DEFAULT=saved
boots the entry specified by the
grub2-once
or grub2-set-default
commands. While grub2-reboot
sets the
default boot entry for the next reboot only,
grub2-set-default
sets the default boot entry until
changed. grub2-editenv list
lists the next boot entry.
GRUB_HIDDEN_TIMEOUT
Waits the specified number of seconds for the user to press a key.
During the period no menu is shown unless the user presses a key. If no
key is pressed during the time specified, the control is passed to
GRUB_TIMEOUT
.
GRUB_HIDDEN_TIMEOUT=0
first checks whether
Shift is pressed and shows the boot menu if yes,
otherwise immediately boots the default menu entry. This is the default
when only one bootable OS is identified by GRUB 2.
GRUB_HIDDEN_TIMEOUT_QUIET
If false
is specified, a countdown timer is displayed
on a blank screen when the GRUB_HIDDEN_TIMEOUT
feature is active.
GRUB_TIMEOUT
Time period in seconds the boot menu is displayed before automatically
booting the default boot entry. If you press a key, the timeout is
cancelled and GRUB 2 waits for you to make the selection manually.
GRUB_TIMEOUT=-1
will cause the menu to be displayed
until you select the boot entry manually.
GRUB_CMDLINE_LINUX
Entries on this line are added at the end of the boot entries for normal and recovery mode. Use it to add kernel parameters to the boot entry.
GRUB_CMDLINE_LINUX_DEFAULT
Same as GRUB_CMDLINE_LINUX
but the entries are
appended in the normal mode only.
GRUB_CMDLINE_LINUX_RECOVERY
Same as GRUB_CMDLINE_LINUX
but the entries are
appended in the recovery mode only.
GRUB_CMDLINE_LINUX_XEN_REPLACE
This entry will completely replace the
GRUB_CMDLINE_LINUX
parameters for all Xen boot
entries.
GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT
Same as GRUB_CMDLINE_LINUX_XEN_REPLACE
but it will
only replace parameters ofGRUB_CMDLINE_LINUX_DEFAULT
.
GRUB_CMDLINE_XEN
This entry specifies the kernel parameters for the Xen guest kernel
only—the operation principle is the same as for
GRUB_CMDLINE_LINUX
.
GRUB_CMDLINE_XEN_DEFAULT
Same as GRUB_CMDLINE_XEN
—the operation
principle is the same as for
GRUB_CMDLINE_LINUX_DEFAULT
.
GRUB_TERMINAL
Enables and specifies an input/output terminal device. Can be
console
(PC BIOS and EFI consoles),
serial
(serial terminal),
ofconsole
(Open Firmware console), or the default
gfxterm
(graphics-mode output). It is also possible
to enable more than one device by quoting the required options, for
example GRUB_TERMINAL="console serial"
.
GRUB_GFXMODE
The resolution used for the gfxterm
graphical
terminal. Note that you can only use modes supported by your graphics
card (VBE). The default is ‘auto’, which tries to select a preferred
resolution. You can display the screen resolutions available to GRUB 2
by typing videoinfo
in the GRUB 2 command line. The
command line is accessed by typing C when the GRUB 2
boot menu screen is displayed.
You can also specify a color depth by appending it to the resolution
setting, for example GRUB_GFXMODE=1280x1024x24
.
GRUB_BACKGROUND
Set a background image for the gfxterm
graphical
terminal. The image must be a file readable by GRUB 2 at boot time, and
it must end with the .png
, .tga
,
.jpg
, or .jpeg
suffix. If
necessary, the image will be scaled to fit the screen.
GRUB_DISABLE_OS_PROBER
If this option is set to true
, automatic searching
for other operating systems is disabled. Only the kernel images in
/boot/
and the options from your own scripts in
/etc/grub.d/
are detected.
SUSE_BTRFS_SNAPSHOT_BOOTING
If this option is set to true
, GRUB 2 can boot
directly into Snapper snapshots. For more information, see
Section 3.3, “System Rollback by Booting from Snapshots”.
For a complete list of options, see the GNU GRUB manual.
/etc/grub.d
#Edit source
The scripts in this directory are read during execution of the
command grub2-mkconfig -o /boot/grub2/grub.cfg
. Their instructions are
incorporated into /boot/grub2/grub.cfg
. The order of
menu items in grub.cfg
is determined by the order in
which the files in this directory are run. Files with a leading numeral are
executed first, beginning with the lowest number.
00_header
is run before 10_linux
,
which would run before 40_custom
. If files with
alphabetic names are present, they are executed after the numerically-named
files. Only executable files generate output to
grub.cfg
during execution of
grub2-mkconfig
. By default all files in the
/etc/grub.d
directory are executable.
grub.cfg
Because /boot/grub2/grub.cfg
is recompiled each time
grub2-mkconfig
is run, any custom content is lost.
If you want to insert your lines directly into
/boot/grub2/grub.cfg
without losing them after
grub2-mkconfig
is run, insert them between
### BEGIN /etc/grub.d/90_persistent ###
and
### END /etc/grub.d/90_persistent ###
The 90_persistent
script ensures that such
content will be preserved.
A list of the most important scripts follows:
00_header
Sets environmental variables such as system file locations, display
settings, themes, and previously saved entries. It also imports
preferences stored in the /etc/default/grub
.
Normally you do not need to make changes to this file.
10_linux
Identifies Linux kernels on the root device and creates relevant menu entries. This includes the associated recovery mode option if enabled. Only the latest kernel is displayed on the main menu page, with additional kernels included in a submenu.
30_os-prober
This script uses os-prober
to search for Linux and
other operating systems and places the results in the GRUB 2 menu. There
are sections to identify specific other operating systems, such as
Windows or macOS.
40_custom
This file provides a simple way to include custom boot entries into
grub.cfg
. Make sure that you do not change the
exec tail -n +3 $0
part at the beginning.
The processing sequence is set by the preceding numbers with the lowest number being executed first. If scripts are preceded by the same number the alphabetical order of the complete name decides the order.
/boot/grub2/custom.cfg
If you create /boot/grub2/custom.cfg
and fill
it with content, it will be automatically included into
/boot/grub2/grub.cfg
just after 40_custom at
boot time.
In GRUB Legacy, the device.map
configuration file was
used to derive Linux device names from BIOS drive numbers. The mapping
between BIOS drives and Linux devices cannot always be guessed correctly.
For example, GRUB Legacy would get a wrong order if the boot sequence of
IDE and SCSI drives is exchanged in the BIOS configuration.
GRUB 2 avoids this problem by using device ID strings (UUIDs) or file
system labels when generating grub.cfg
. GRUB 2
utilities create a temporary device map on the fly, which is usually
sufficient, particularly in the case of single-disk systems.
However, if you need to override the GRUB 2's automatic device mapping
mechanism, create your custom mapping file
/boot/grub2/device.map
. The following example changes
the mapping to make DISK 3
the boot disk. Note that
GRUB 2 partition numbers start with 1
and not with
0
as in GRUB Legacy.
(hd1) /dev/disk-by-id/DISK3 ID (hd2) /dev/disk-by-id/DISK1 ID (hd3) /dev/disk-by-id/DISK2 ID
Even before the operating system is booted, GRUB 2 enables access to file systems. Users without root permissions can access files in your Linux system to which they have no access after the system is booted. To block this kind of access or to prevent users from booting certain menu entries, set a boot password.
If set, the boot password is required on every boot, which means the system does not boot automatically.
Proceed as follows to set a boot password. Alternatively use YaST ().
Encrypt the password using grub2-mkpasswd-pbkdf2:
tux >
sudo
grub2-mkpasswd-pbkdf2 Password: **** Reenter password: **** PBKDF2 hash of your password is grub.pbkdf2.sha512.10000.9CA4611006FE96BC77A...
Paste the resulting string into the file
/etc/grub.d/40_custom
together with the set
superusers
command.
set superusers="root" password_pbkdf2 root grub.pbkdf2.sha512.10000.9CA4611006FE96BC77A...
To import the changes into the main configuration file, run:
tux >
sudo
grub2-mkconfig -o /boot/grub2/grub.cfg
After you reboot, you will be prompted for a user name and a password when
trying to boot a menu entry. Enter root
and the password
you typed during the grub2-mkpasswd-pbkdf2
command. If
the credentials are correct, the system will boot the selected boot entry.
For more information, see https://www.gnu.org/software/grub/manual/grub.html#Security.
The easiest way to configure general options of the boot loader in your openSUSE Leap system is to use the YaST module. In the , select › . The module shows the current boot loader configuration of your system and allows you to make changes.
Use the
tab to view and change settings related to type, location and advanced loader settings. You can choose whether to use GRUB 2 in standard or EFI mode.If you have an EFI system you can only install GRUB2-EFI, otherwise your system is no longer bootable.
To reinstall the boot loader, make sure to change a setting in YaST and then change it back. For example, to reinstall GRUB2-EFI, select
first and then immediately switch back to .Otherwise, the boot loader may only be partially reinstalled.
To use a boot loader other than the ones listed, select
. Read the documentation of your boot loader carefully before choosing this option.
The default location of the boot loader depends on the partition setup and
is either the Master Boot Record (MBR) or the boot sector of the
/
partition. To modify the location of the boot loader,
follow these steps:
Select the
tab and then choose one of the following options for :
This installs the boot loader in the MBR of the disk containing the
directory /boot
. Usually this will be the disk
mounted to /
, but if /boot
is
mounted to a separate partition on a different disk, the MBR of that
disk will be used.
This installs the boot loader in the boot sector of the
/
partition.
Use this option to specify the location of the boot loader manually.
Click
to apply your changes.The
tab includes the following additional options:
Activates the partition that contains the
/boot
directory. For POWER systems it
activates the PReP partition. Use this option on systems with
old BIOS and/or legacy operating systems because they may fail
to boot from a non-active partition. It is safe to leave this
option active.
If MBR contains a custom 'non-GRUB' code, this option replaces it with a generic, operating system independent code. If you deactivate this option, the system may become unbootable.
Starts TrustedGRUB2, which supports trusted computing functionality (Trusted Platform Module (TPM)). For more information refer to https://github.com/Sirrix-AG/TrustedGRUB2.
The
section includes the following options:This is appropriate for traditional legacy BIOS booting.
This is appropriate for UEFI booting.
This is usually the best choice if you have an already working system.
In most cases YaST defaults to the appropriate choice.
If your computer has more than one hard disk, you can specify the boot sequence of the disks. The first disk in the list is where GRUB 2 will be installed in the case of booting from MBR. It is the disk where openSUSE Leap is installed by default. The rest of the list is a hint for GRUB 2's device mapper (see Section 12.2.4, “Mapping between BIOS Drives and Linux Devices”).
The default value is usually valid for almost all deployments. If you change the boot order of disks wrongly, the system may become unbootable on the next reboot. For example, if the first disk in the list is not part of the BIOS boot order, and the other disks in the list have empty MBRs.
Open the
tab.Click
.If more than one disk is listed, select a disk and click
or to reorder the displayed disks.Click
two times to save the changes.Advanced boot parameters can be configured via the
tab.Change the value of
by typing in a new value and clicking the appropriate arrow key with your mouse.When selected, the boot loader searches for other systems like Windows or other Linux installations.
Hides the boot menu and boots the default entry.
Select the desired entry from the “Default Boot Section” list. Note that the “>” sign in the boot entry name delimits the boot section and its subsection.
Protects the boot loader and the system with an additional password. For
details on manual configuration, see Section 12.2.6, “Setting a Boot Password”.
If this option is activated, the boot password is required on every boot,
which means the system does not boot automatically. However, if you prefer
the behavior of GRUB 1, additionally enable . With this setting, anybody is allowed to select
a boot entry and boot the system, whereas the password for the GRUB 2 root
user is only required for modifying boot entries.
Specify optional kernel parameters here to enable/disable system features, add drivers, etc.
SUSE has released one or more kernel boot command line parameters for all software mitigations that have been deployed to prevent CPU side-channel attacks. Some of those may result in performance loss. Choose one the following options to strike a balance between security and performance, depending on your setting:
Enables all mitigations required for your CPU model, but does not protect against cross-CPU thread attacks. This setting may impact performance to some degree, depending on the workload. .
Provides the full set of available security mitigations. Enables all mitigations required for your CPU model. In addition, it disables Simultaneous Multithreading (SMT) to avoid side-channel attacks across multiple CPU threads. This setting may further impact performance, depending on the workload. .
Disables all mitigations. Side-channel attacks against your CPU are possible, depending on the CPU model. This setting has no impact on performance. .
Does not set any mitigation level. Specify your CPU mitigations manually by using the kernel command line options. .
When checked, the boot menu appears on a graphical splash screen rather than in a text mode. The resolution of the boot screen is set automatically by default, but you can manually set it via
. The graphical theme definition file can be specified with the file-chooser. Only change this if you want to apply your own, custom-made theme.
If your machine is controlled via a serial console, activate this option
and specify which COM port to use at which speed. See info
grub
or
http://www.gnu.org/software/grub/manual/grub.html#Serial-terminal
grub2-mkconfig
Generates a new /boot/grub2/grub.cfg
based on
/etc/default/grub
and the scripts from
/etc/grub.d/
.
grub2-mkconfig -o /boot/grub2/grub.cfg
Running grub2-mkconfig
without any parameters prints
the configuration to STDOUT where it can be reviewed. Use
grub2-script-check
after
/boot/grub2/grub.cfg
has been written to check its
syntax.
grub2-mkconfig
Cannot Repair UEFI Secure Boot TablesIf you are using UEFI Secure Boot and your system is not reaching GRUB 2 correctly anymore, you may need to additionally reinstall Shim and regenerate the UEFI boot table. To do so, use:
root #
shim-install --config-file=/boot/grub2/grub.cfg
grub2-mkrescue
Creates a bootable rescue image of your installed GRUB 2 configuration.
grub2-mkrescue -o save_path/name.iso iso
grub2-script-check
Checks the given file for syntax errors.
grub2-script-check /boot/grub2/grub.cfg
grub2-once
Set the default boot entry for the next boot only. To get the list of
available boot entries use the --list
option.
grub2-once number_of_the_boot_entry
grub2-once
HelpCall the program without any option to get a full list of all possible options.
Extensive information about GRUB 2 is available at https://www.gnu.org/software/grub/. Also refer to the
grub
info page.
Linux offers the necessary networking tools and features for integration into all types of network structures. Network access using a network card can be configured with YaST. Manual configuration is also possible. In this chapter only the fundamental mechanisms and the relevant network configuration files are covered.
Linux and other Unix operating systems use the TCP/IP protocol. It is not a single network protocol, but a family of network protocols that offer various services. The protocols listed in Several Protocols in the TCP/IP Protocol Family, are provided for exchanging data between two machines via TCP/IP. Networks combined by TCP/IP, comprising a worldwide network, are also called “the Internet.”
RFC stands for Request for Comments. RFCs are documents that describe various Internet protocols and implementation procedures for the operating system and its applications. The RFC documents describe the setup of Internet protocols. For more information about RFCs, see http://www.ietf.org/rfc.html.
Transmission Control Protocol: a connection-oriented secure protocol. The data to transmit is first sent by the application as a stream of data and converted into the appropriate format by the operating system. The data arrives at the respective application on the destination host in the original data stream format it was initially sent. TCP determines whether any data has been lost or jumbled during the transmission. TCP is implemented wherever the data sequence matters.
User Datagram Protocol: a connectionless, insecure protocol. The data to transmit is sent in the form of packets generated by the application. The order in which the data arrives at the recipient is not guaranteed and data loss is possible. UDP is suitable for record-oriented applications. It features a smaller latency period than TCP.
Internet Control Message Protocol: This is not a protocol for the end user, but a special control protocol that issues error reports and can control the behavior of machines participating in TCP/IP data transfer. In addition, it provides a special echo mode that can be viewed using the program ping.
Internet Group Management Protocol: This protocol controls machine behavior when implementing IP multicast.
As shown in Figure 13.1, “Simplified Layer Model for TCP/IP”, data exchange takes place in different layers. The actual network layer is the insecure data transfer via IP (Internet protocol). On top of IP, TCP (transmission control protocol) guarantees, to a certain extent, security of the data transfer. The IP layer is supported by the underlying hardware-dependent protocol, such as Ethernet.
The diagram provides one or two examples for each layer. The layers are ordered according to abstraction levels. The lowest layer is very close to the hardware. The uppermost layer, however, is almost a complete abstraction from the hardware. Every layer has its own special function. The special functions of each layer are mostly implicit in their description. The data link and physical layers represent the physical network used, such as Ethernet.
Almost all hardware protocols work on a packet-oriented basis. The data to transmit is collected into packets (it cannot be sent all at once). The maximum size of a TCP/IP packet is approximately 64 KB. Packets are normally quite smaller, as the network hardware can be a limiting factor. The maximum size of a data packet on an Ethernet is about fifteen hundred bytes. The size of a TCP/IP packet is limited to this amount when the data is sent over an Ethernet. If more data is transferred, more data packets need to be sent by the operating system.
For the layers to serve their designated functions, additional information regarding each layer must be saved in the data packet. This takes place in the header of the packet. Every layer attaches a small block of data, called the protocol header, to the front of each emerging packet. A sample TCP/IP data packet traveling over an Ethernet cable is illustrated in Figure 13.2, “TCP/IP Ethernet Packet”. The proof sum is located at the end of the packet, not at the beginning. This simplifies things for the network hardware.
When an application sends data over the network, the data passes through each layer, all implemented in the Linux kernel except the physical layer. Each layer is responsible for preparing the data so it can be passed to the next layer. The lowest layer is ultimately responsible for sending the data. The entire procedure is reversed when data is received. Like the layers of an onion, in each layer the protocol headers are removed from the transported data. Finally, the transport layer is responsible for making the data available for use by the applications at the destination. In this manner, one layer only communicates with the layer directly above or below it. For applications, it is irrelevant whether data is transmitted via a wireless or wired connection. Likewise, it is irrelevant for the data line which kind of data is transmitted, as long as packets are in the correct format.
The discussion in this section is limited to IPv4 networks. For information about IPv6 protocol, the successor to IPv4, refer to Section 13.2, “IPv6—The Next Generation Internet”.
Every computer on the Internet has a unique 32-bit address. These 32 bits (or 4 bytes) are normally written as illustrated in the second row in Example 13.1, “Writing IP Addresses”.
IP Address (binary): 11000000 10101000 00000000 00010100 IP Address (decimal): 192. 168. 0. 20
In decimal form, the four bytes are written in the decimal number system, separated by periods. The IP address is assigned to a host or a network interface. It can be used only once throughout the world. There are exceptions to this rule, but these are not relevant to the following passages.
The points in IP addresses indicate the hierarchical system. Until the 1990s, IP addresses were strictly categorized in classes. However, this system proved too inflexible and was discontinued. Now, classless routing (CIDR, classless interdomain routing) is used.
Netmasks are used to define the address range of a subnet. If two hosts are in the same subnet, they can reach each other directly. If they are not in the same subnet, they need the address of a gateway that handles all the traffic for the subnet. To check if two IP addresses are in the same subnet, simply “AND” both addresses with the netmask. If the result is identical, both IP addresses are in the same local network. If there are differences, the remote IP address, and thus the remote interface, can only be reached over a gateway.
To understand how the netmask works, look at
Example 13.2, “Linking IP Addresses to the Netmask”. The netmask consists of 32 bits
that identify how much of an IP address belongs to the network. All those
bits that are 1
mark the corresponding bit in the IP
address as belonging to the network. All bits that are 0
mark bits inside the subnet. This means that the more bits are
1
, the smaller the subnet is. Because the netmask always
consists of several successive 1
bits, it is also
possible to count the number of bits in the netmask. In
Example 13.2, “Linking IP Addresses to the Netmask” the first net with 24 bits could
also be written as 192.168.0.0/24
.
IP address (192.168.0.20): 11000000 10101000 00000000 00010100 Netmask (255.255.255.0): 11111111 11111111 11111111 00000000 --------------------------------------------------------------- Result of the link: 11000000 10101000 00000000 00000000 In the decimal system: 192. 168. 0. 0 IP address (213.95.15.200): 11010101 10111111 00001111 11001000 Netmask (255.255.255.0): 11111111 11111111 11111111 00000000 --------------------------------------------------------------- Result of the link: 11010101 10111111 00001111 00000000 In the decimal system: 213. 95. 15. 0
To give another example: all machines connected with the same Ethernet cable are usually located in the same subnet and are directly accessible. Even when the subnet is physically divided by switches or bridges, these hosts can still be reached directly.
IP addresses outside the local subnet can only be reached if a gateway is configured for the target network. In the most common case, there is only one gateway that handles all traffic that is external. However, it is also possible to configure several gateways for different subnets.
If a gateway has been configured, all external IP packets are sent to the appropriate gateway. This gateway then attempts to forward the packets in the same manner—from host to host—until it reaches the destination host or the packet's TTL (time to live) expires.
This is the netmask AND any address in the network, as shown in
Example 13.2, “Linking IP Addresses to the Netmask” under Result
.
This address cannot be assigned to any hosts.
This could be paraphrased as: “Access all hosts in this subnet.” To generate this, the netmask is inverted in binary form and linked to the base network address with a logical OR. The above example therefore results in 192.168.0.255. This address cannot be assigned to any hosts.
The address 127.0.0.1
is
assigned to the “loopback device” on each host. A
connection can be set up to your own machine with this address and with
all addresses from the complete
127.0.0.0/8
loopback network
as defined with IPv4. With IPv6 there is only one loopback address
(::1
).
Because IP addresses must be unique all over the world, you cannot select random addresses. There are three address domains to use if you want to set up a private IP-based network. These cannot get any connection from the rest of the Internet, because they cannot be transmitted over the Internet. These address domains are specified in RFC 1597 and listed in Table 13.1, “Private IP Address Domains”.
Network/Netmask |
Domain |
---|---|
|
|
|
|
|
|
Because of the emergence of the World Wide Web (WWW), the Internet has experienced explosive growth, with an increasing number of computers communicating via TCP/IP in the past fifteen years. Since Tim Berners-Lee at CERN (http://public.web.cern.ch) invented the WWW in 1990, the number of Internet hosts has grown from a few thousand to about a hundred million.
As mentioned, an IPv4 address consists of only 32 bits. Also, quite a few IP addresses are lost—they cannot be used because of the way in which networks are organized. The number of addresses available in your subnet is two to the power of the number of bits, minus two. A subnet has, for example, 2, 6, or 14 addresses available. To connect 128 hosts to the Internet, for example, you need a subnet with 256 IP addresses, from which only 254 are usable, because two IP addresses are needed for the structure of the subnet itself: the broadcast and the base network address.
Under the current IPv4 protocol, DHCP or NAT (network address translation) are the typical mechanisms used to circumvent the potential address shortage. Combined with the convention to keep private and public address spaces separate, these methods can certainly mitigate the shortage. The problem with them lies in their configuration, which is a chore to set up and a burden to maintain. To set up a host in an IPv4 network, you need several address items, such as the host's own IP address, the subnetmask, the gateway address and maybe a name server address. All these items need to be known and cannot be derived from somewhere else.
With IPv6, both the address shortage and the complicated configuration should be a thing of the past. The following sections tell more about the improvements and benefits brought by IPv6 and about the transition from the old protocol to the new one.
The most important and most visible improvement brought by the new protocol is the enormous expansion of the available address space. An IPv6 address is made up of 128 bit values instead of the traditional 32 bits. This provides for as many as several quadrillion IP addresses.
However, IPv6 addresses are not only different from their predecessors with regard to their length. They also have a different internal structure that may contain more specific information about the systems and the networks to which they belong. More details about this are found in Section 13.2.2, “Address Types and Structure”.
The following is a list of other advantages of the new protocol:
IPv6 makes the network “plug and play” capable, which means that a newly set up system integrates into the (local) network without any manual configuration. The new host uses its automatic configuration mechanism to derive its own address from the information made available by the neighboring routers, relying on a protocol called the neighbor discovery (ND) protocol. This method does not require any intervention on the administrator's part and there is no need to maintain a central server for address allocation—an additional advantage over IPv4, where automatic address allocation requires a DHCP server.
Nevertheless if a router is connected to a switch, the router should
send periodic advertisements with flags telling the hosts of a network
how they should interact with each other. For more information, see
RFC 2462 and the radvd.conf(5)
man page, and
RFC 3315.
IPv6 makes it possible to assign several addresses to one network interface at the same time. This allows users to access several networks easily, something that could be compared with the international roaming services offered by mobile phone companies. When you take your mobile phone abroad, the phone automatically logs in to a foreign service when it enters the corresponding area, so you can be reached under the same number everywhere and can place an outgoing call, as you would in your home area.
With IPv4, network security is an add-on function. IPv6 includes IPsec as one of its core features, allowing systems to communicate over a secure tunnel to avoid eavesdropping by outsiders on the Internet.
Realistically, it would be impossible to switch the entire Internet from IPv4 to IPv6 at one time. Therefore, it is crucial that both protocols can coexist not only on the Internet, but also on one system. This is ensured by compatible addresses (IPv4 addresses can easily be translated into IPv6 addresses) and by using several tunnels. See Section 13.2.3, “Coexistence of IPv4 and IPv6”. Also, systems can rely on a dual stack IP technique to support both protocols at the same time, meaning that they have two network stacks that are completely separate, such that there is no interference between the two protocol versions.
With IPv4, some services, such as SMB, need to broadcast their packets to all hosts in the local network. IPv6 allows a much more fine-grained approach by enabling servers to address hosts through multicasting, that is by addressing several hosts as parts of a group. This is different from addressing all hosts through broadcasting or each host individually through unicasting. Which hosts are addressed as a group may depend on the concrete application. There are some predefined groups to address all name servers (the all name servers multicast group), for example, or all routers (the all routers multicast group).
As mentioned, the current IP protocol has two major limitations: there is an increasing shortage of IP addresses, and configuring the network and maintaining the routing tables is becoming a more complex and burdensome task. IPv6 solves the first problem by expanding the address space to 128 bits. The second one is mitigated by introducing a hierarchical address structure combined with sophisticated techniques to allocate network addresses, and multihoming (the ability to assign several addresses to one device, giving access to several networks).
When dealing with IPv6, it is useful to know about three different types of addresses:
Addresses of this type are associated with exactly one network interface. Packets with such an address are delivered to only one destination. Accordingly, unicast addresses are used to transfer packets to individual hosts on the local network or the Internet.
Addresses of this type relate to a group of network interfaces. Packets with such an address are delivered to all destinations that belong to the group. Multicast addresses are mainly used by certain network services to communicate with certain groups of hosts in a well-directed manner.
Addresses of this type are related to a group of interfaces. Packets with such an address are delivered to the member of the group that is closest to the sender, according to the principles of the underlying routing protocol. Anycast addresses are used to make it easier for hosts to find out about servers offering certain services in the given network area. All servers of the same type have the same anycast address. Whenever a host requests a service, it receives a reply from the server with the closest location, as determined by the routing protocol. If this server should fail for some reason, the protocol automatically selects the second closest server, then the third one, and so forth.
An IPv6 address is made up of eight four-digit fields, each representing 16
bits, written in hexadecimal notation. They are separated by colons
(:
). Any leading zero bytes within a given field may be
dropped, but zeros within the field or at its end may not. Another
convention is that more than four consecutive zero bytes may be collapsed
into a double colon. However, only one such ::
is
allowed per address. This kind of shorthand notation is shown in
Example 13.3, “Sample IPv6 Address”, where all three lines represent the
same address.
fe80 : 0000 : 0000 : 0000 : 0000 : 10 : 1000 : 1a4 fe80 : 0 : 0 : 0 : 0 : 10 : 1000 : 1a4 fe80 : : 10 : 1000 : 1a4
Each part of an IPv6 address has a defined function. The first bytes form
the prefix and specify the type of address. The center part is the network
portion of the address, but it may be unused. The end of the address forms
the host part. With IPv6, the netmask is defined by indicating the length
of the prefix after a slash at the end of the address. An address, as shown
in Example 13.4, “IPv6 Address Specifying the Prefix Length”, contains the information that
the first 64 bits form the network part of the address and the last 64 form
its host part. In other words, the 64
means that the
netmask is filled with 64 1-bit values from the left. As with IPv4, the IP
address is combined with AND with the values from the netmask to determine
whether the host is located in the same subnet or in another one.
fe80::10:1000:1a4/64
IPv6 knows about several predefined types of prefixes. Some are shown in Various IPv6 Prefixes.
00
IPv4 addresses and IPv4 over IPv6 compatibility addresses. These are used to maintain compatibility with IPv4. Their use still requires a router able to translate IPv6 packets into IPv4 packets. Several special addresses, such as the one for the loopback device, have this prefix as well.
2
or
3
as the
first digit
Aggregatable global unicast addresses. As is the case with IPv4, an
interface can be assigned to form part of a certain subnet. Currently,
there are the following address spaces:
2001::/16
(production quality
address space) and 2002::/16
(6to4 address space).
fe80::/10
Link-local addresses. Addresses with this prefix should not be routed and should therefore only be reachable from within the same subnet.
fec0::/10
Site-local addresses. These may be routed, but only within the network
of the organization to which they belong. In effect, they are the IPv6
equivalent of the current private network address space, such as
10.x.x.x
.
ff
These are multicast addresses.
A unicast address consists of three basic components:
The first part (which also contains one of the prefixes mentioned above) is used to route packets through the public Internet. It includes information about the company or institution that provides the Internet access.
The second part contains routing information about the subnet to which to deliver the packet.
The third part identifies the interface to which to deliver the packet.
This also allows for the MAC to form part of the address. Given that the
MAC is a globally unique, fixed identifier coded into the device by the
hardware maker, the configuration procedure is substantially simplified.
In fact, the first 64 address bits are consolidated to form the
EUI-64
token, with the last 48 bits taken from the
MAC, and the remaining 24 bits containing special information about the
token type. This also makes it possible to assign an
EUI-64
token to interfaces that do not have a MAC,
such as those based on PPP.
On top of this basic structure, IPv6 distinguishes between five different types of unicast addresses:
::
(unspecified) This address is used by the host as its source address when the interface is initialized for the first time (at which point, the address cannot yet be determined by other means).
::1
(loopback) The address of the loopback device.
The IPv6 address is formed by the IPv4 address and a prefix consisting of 96 zero bits. This type of compatibility address is used for tunneling (see Section 13.2.3, “Coexistence of IPv4 and IPv6”) to allow IPv4 and IPv6 hosts to communicate with others operating in a pure IPv4 environment.
This type of address specifies a pure IPv4 address in IPv6 notation.
There are two address types for local use:
This type of address can only be used in the local subnet. Packets
with a source or target address of this type should not be routed to
the Internet or other subnets. These addresses contain a special
prefix (fe80::/10
) and the
interface ID of the network card, with the middle part consisting of
zero bytes. Addresses of this type are used during automatic
configuration to communicate with other hosts belonging to the same
subnet.
Packets with this type of address may be routed to other subnets, but
not to the wider Internet—they must remain inside the
organization's own network. Such addresses are used for intranets and
are an equivalent of the private address space defined by IPv4. They
contain a special prefix
(fec0::/10
), the interface
ID, and a 16 bit field specifying the subnet ID. Again, the rest is
filled with zero bytes.
As a completely new feature introduced with IPv6, each network interface normally gets several IP addresses, with the advantage that several networks can be accessed through the same interface. One of these networks can be configured completely automatically using the MAC and a known prefix with the result that all hosts on the local network can be reached when IPv6 is enabled (using the link-local address). With the MAC forming part of it, any IP address used in the world is unique. The only variable parts of the address are those specifying the site topology and the public topology, depending on the actual network in which the host is currently operating.
For a host to go back and forth between different networks, it needs at least two addresses. One of them, the home address, not only contains the interface ID but also an identifier of the home network to which it normally belongs (and the corresponding prefix). The home address is a static address and, as such, it does not normally change. Still, all packets destined to the mobile host can be delivered to it, regardless of whether it operates in the home network or somewhere outside. This is made possible by the completely new features introduced with IPv6, such as stateless autoconfiguration and neighbor discovery. In addition to its home address, a mobile host gets one or more additional addresses that belong to the foreign networks where it is roaming. These are called care-of addresses. The home network has a facility that forwards any packets destined to the host when it is roaming outside. In an IPv6 environment, this task is performed by the home agent, which takes all packets destined to the home address and relays them through a tunnel. On the other hand, those packets destined to the care-of address are directly transferred to the mobile host without any special detours.
The migration of all hosts connected to the Internet from IPv4 to IPv6 is a gradual process. Both protocols will coexist for some time to come. The coexistence on one system is guaranteed where there is a dual stack implementation of both protocols. That still leaves the question of how an IPv6 enabled host should communicate with an IPv4 host and how IPv6 packets should be transported by the current networks, which are predominantly IPv4-based. The best solutions offer tunneling and compatibility addresses (see Section 13.2.2, “Address Types and Structure”).
IPv6 hosts that are more or less isolated in the (worldwide) IPv4 network can communicate through tunnels: IPv6 packets are encapsulated as IPv4 packets to move them across an IPv4 network. Such a connection between two IPv4 hosts is called a tunnel. To achieve this, packets must include the IPv6 destination address (or the corresponding prefix) and the IPv4 address of the remote host at the receiving end of the tunnel. A basic tunnel can be configured manually according to an agreement between the hosts' administrators. This is also called static tunneling.
However, the configuration and maintenance of static tunnels is often too labor-intensive to use them for daily communication needs. Therefore, IPv6 provides for three different methods of dynamic tunneling:
IPv6 packets are automatically encapsulated as IPv4 packets and sent over an IPv4 network capable of multicasting. IPv6 is tricked into seeing the whole network (Internet) as a huge local area network (LAN). This makes it possible to determine the receiving end of the IPv4 tunnel automatically. However, this method does not scale very well and is also hampered because IP multicasting is far from widespread on the Internet. Therefore, it only provides a solution for smaller corporate or institutional networks where multicasting can be enabled. The specifications for this method are laid down in RFC 2529.
With this method, IPv4 addresses are automatically generated from IPv6 addresses, enabling isolated IPv6 hosts to communicate over an IPv4 network. However, several problems have been reported regarding the communication between those isolated IPv6 hosts and the Internet. The method is described in RFC 3056.
This method relies on special servers that provide dedicated tunnels for IPv6 hosts. It is described in RFC 3053.
To configure IPv6, you normally do not need to make any changes on the
individual workstations. IPv6 is enabled by default. To disable or enable
IPv6 on an installed system, use the YaST modprobe
-i ipv6
as
root
. It is impossible to unload
the IPv6 module after it has been loaded.
Because of the autoconfiguration concept of IPv6, the network card is assigned an address in the link-local network. Normally, no routing table management takes place on a workstation. The network routers can be queried by the workstation, using the router advertisement protocol, for what prefix and gateways should be implemented. The radvd program can be used to set up an IPv6 router. This program informs the workstations which prefix to use for the IPv6 addresses and which routers. Alternatively, use zebra/quagga for automatic configuration of both addresses and routing.
For information about how to set up various types of tunnels using the
/etc/sysconfig/network
files, see the man page of
ifcfg-tunnel
(man ifcfg-tunnel
).
The above overview does not cover the topic of IPv6 comprehensively. For a more in-depth look at the new protocol, refer to the following online documentation and books:
The starting point for everything about IPv6.
All information needed to start your own IPv6 network.
The list of IPv6-enabled products.
Here, find the Linux IPv6-HOWTO and many links related to the topic.
The fundamental RFC about IPv6.
A book describing all the important aspects of the topic is IPv6 Essentials by Silvia Hagen (ISBN 0-596-00125-8).
DNS assists in assigning an IP address to one or more names and assigning a name to an IP address. In Linux, this conversion is usually carried out by a special type of software known as bind. The machine that takes care of this conversion is called a name server. The names make up a hierarchical system in which each name component is separated by a period. The name hierarchy is, however, independent of the IP address hierarchy described above.
Consider a complete name, such as
jupiter.example.com
, written in the
format hostname.domain
. A full
name, called a fully qualified domain name (FQDN),
consists of a host name and a domain name
(example.com
). The latter
also includes the top level domain or TLD
(com
).
TLD assignment has become quite confusing for historical reasons.
Traditionally, three-letter domain names are used in the USA. In the rest of
the world, the two-letter ISO national codes are the standard. In addition
to that, longer TLDs were introduced in 2000 that represent certain spheres
of activity (for example, .info
,
.name
,
.museum
).
In the early days of the Internet (before 1990), the file
/etc/hosts
was used to store the names of all the
machines represented over the Internet. This quickly proved to be
impractical in the face of the rapidly growing number of computers connected
to the Internet. For this reason, a decentralized database was developed to
store the host names in a widely distributed manner. This database, similar
to the name server, does not have the data pertaining to all hosts in the
Internet readily available, but can dispatch requests to other name servers.
The top of the hierarchy is occupied by root name servers. These root name servers manage the top level domains and are run by the Network Information Center (NIC). Each root name server knows about the name servers responsible for a given top level domain. Information about top level domain NICs is available at http://www.internic.net.
DNS can do more than resolve host names. The name server also knows which host is receiving e-mails for an entire domain—the mail exchanger (MX).
For your machine to resolve an IP address, it must know about at least one name server and its IP address. Easily specify such a name server using YaST. The configuration of name server access with openSUSE® Leap is described in Section 13.4.1.4, “Configuring Host Name and DNS”. Setting up your own name server is described in Chapter 19, The Domain Name System.
The protocol whois
is closely related to DNS. With this
program, quickly find out who is responsible for a given domain.
The .local
top level domain is treated as link-local
domain by the resolver. DNS requests are send as multicast DNS requests
instead of normal DNS requests. If you already use the
.local
domain in your name server configuration, you
must switch this option off in /etc/host.conf
. For
more information, see the host.conf
manual page.
To switch off MDNS during installation, use
nomdns=1
as a boot parameter.
For more information on multicast DNS, see http://www.multicastdns.org.
There are many supported networking types on Linux. Most of them use different device names and the configuration files are spread over several locations in the file system. For a detailed overview of the aspects of manual network configuration, see Section 13.6, “Configuring a Network Connection Manually”.
All network interfaces with link up (with a network cable connected) are automatically configured. Additional hardware can be configured any time on the installed system. The following sections describe the network configuration for all types of network connections supported by openSUSE Leap.
To configure your Ethernet or Wi-Fi/Bluetooth card in YaST, select
› . After starting the module, YaST displays the dialog with four tabs: , , and .The Section 13.4.1.1, “Configuring Global Networking Options”.
tab allows you to set general networking options such as the network setup method, IPv6, and general DHCP options. For more information, seeThe Section 13.4.1.3, “Configuring an Undetected Network Card”. To change the configuration of an already configured card, see Section 13.4.1.2, “Changing the Configuration of a Network Card”.
tab contains information about installed network interfaces and configurations. Any properly detected network card is listed with its name. You can manually configure new cards, remove or change their configuration in this dialog. To manually configure a card that was not automatically detected, seeThe Section 13.4.1.4, “Configuring Host Name and DNS”.
tab allows to set the host name of the machine and name the servers to be used. For more information, seeThe Section 13.4.1.5, “Configuring Routing” for more information.
tab is used for the configuration of routing. SeeThe
tab of the YaST module allows you to set important global networking options, such as the use of NetworkManager, IPv6 and DHCP client options. These settings are applicable for all network interfaces.
In the nm-applet
should be used to configure
network options and the ,
and tabs of the
module are disabled.
For more information on NetworkManager, see
Chapter 28, Using NetworkManager.
In the
choose whether to use the IPv6 protocol. It is possible to use IPv6 together with IPv4. By default, IPv6 is enabled. However, in networks not using IPv6 protocol, response times can be faster with IPv6 protocol disabled. To disable IPv6, deactivate . If IPv6 is disabled, the kernel no longer loads the IPv6 module automatically. This setting will be applied after reboot.In the
configure options for the DHCP client. The must be different for each DHCP client on a single network. If left empty, it defaults to the hardware address of the network interface. However, if you are running several virtual machines using the same network interface and, therefore, the same hardware address, specify a unique free-form identifier here.
The AUTO
to
send the current host name (that is the one defined in
/etc/HOSTNAME
). Make the option field empty for not
sending any host name.
If you do not want to change the default route according to the information from DHCP, deactivate
.To change the configuration of a network card, select a card from the list of the detected cards in
› in YaST and click . The dialog appears in which to adjust the card configuration using the , and tabs.You can set the IP address of the network card or the way its IP address is determined in the
tab of the dialog. Both IPv4 and IPv6 addresses are supported. The network card can have (which is useful for bonding devices), a (IPv4 or IPv6) or a assigned via or or both.If using
, select whether to use (for IPv4), (for IPv6) or .If possible, the first network card with link that is available during the installation is automatically configured to use automatic address setup via DHCP.
DHCP should also be used if you are using a DSL line but with no static IP assigned by the ISP (Internet Service Provider). If you decide to use DHCP, configure the details in
in the tab of the dialog of the YaST network card configuration module. If you have a virtual host setup where different hosts communicate through the same interface, an is necessary to distinguish them.DHCP is a good choice for client configuration but it is not ideal for server configuration. To set a static IP address, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST network card configuration module and click .In the
tab, choose .
Enter the /64
.
Optionally, you can enter a fully qualified /etc/hosts
configuration file.
Click
.To activate the configuration, click
.
During activation of a network interface, wicked
checks for a carrier and only applies the IP configuration when a link
has been detected. If you need to apply the configuration regardless of
the link status (for example, when you want to test a service listening to a
certain address), you can skip link detection by adding the variable
LINK_REQUIRED=no
to the configuration file of the
interface in /etc/sysconfig/network/ifcfg
.
Additionally, you can use the variable
LINK_READY_WAIT=5
to
specify the timeout for waiting for a link in seconds.
For more information about the ifcfg-*
configuration
files, refer to Section 13.6.2.5, “/etc/sysconfig/network/ifcfg-*
” and
man 5 ifcfg
.
If you use the static address, the name servers and default gateway are not configured automatically. To configure name servers, proceed as described in Section 13.4.1.4, “Configuring Host Name and DNS”. To configure a gateway, proceed as described in Section 13.4.1.5, “Configuring Routing”.
One network device can have multiple IP addresses.
These so-called aliases or labels, respectively, work with IPv4 only.
With IPv6 they will be ignored. Using iproute2
network
interfaces can have one or more addresses.
Using YaST to set additional addresses for your network card, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST dialog and click .In the
› tab, click .Enter
, , and . Do not include the interface name in the alias name.To activate the configuration, confirm the settings.
It is possible to change the device name of the network card when it is used. It is also possible to determine whether the network card should be identified by udev via its hardware (MAC) address or via the bus ID. The latter option is preferable in large servers to simplify hotplugging of cards. To set these options with YaST, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST dialog and click .Go to the
tab. The current device name is shown in . Click .Select whether udev should identify the card by its
or . The current MAC address and bus ID of the card are shown in the dialog.To change the device name, check the
option and edit the name.To activate the configuration, confirm the settings.
For some network cards, several kernel drivers may be available. If the card is already configured, YaST allows you to select a kernel driver to be used from a list of available suitable drivers. It is also possible to specify options for the kernel driver. To set these options with YaST, proceed as follows:
Select a card from the list of detected cards in the
tab of the YaST Network Settings module and click .Go to the
tab.
Select the kernel driver to be used in =
=VALUE. If more options
are used, they should be space-separated.
To activate the configuration, confirm the settings.
If you use the method with wicked
, you can configure
your device to either start during boot, on cable connection, on card
detection, manually, or never. To change device start-up, proceed as
follows:
In YaST select a card from the list of detected cards in
› and click .In the
tab, select the desired entry from .
Choose ifup
. Choose to not start
the device. The is similar to , but the interface does not shut down with the
systemctl stop network
command; the
network
service also cares about the
wicked
service if wicked
is active.
Use this if you use an NFS or iSCSI root file system.
To activate the configuration, confirm the settings.
On (diskless) systems where the root partition is mounted via network as an NFS share, you need to be careful when configuring the network device with which the NFS share is accessible.
When shutting down or rebooting the system, the default processing order is to turn off network connections, then unmount the root partition. With NFS root, this order causes problems as the root partition cannot be cleanly unmounted as the network connection to the NFS share is already not activated. To prevent the system from deactivating the relevant network device, open the network device configuration tab as described in Section 13.4.1.2.5, “Activating the Network Device” and choose in the pane.
You can set a maximum transmission unit (MTU) for the interface. MTU refers to the largest allowed packet size in bytes. A higher MTU brings higher bandwidth efficiency. However, large packets can block up a slow interface for some time, increasing the lag for further packets.
In YaST select a card from the list of detected cards in
› and click .In the
tab, select the desired entry from the list.To activate the configuration, confirm the settings.
Multifunction devices that support LAN, iSCSI, and FCoE are supported.
The YaST FCoE client (yast2 fcoe-client
) shows the
private flags in additional columns to allow the user to select the device
meant for FCoE. The YaST network module (yast2 lan
)
excludes “storage only devices” for network configuration.
In YaST select the InfiniBand device in
› and click .In the
tab, select one of the (IPoIB) modes: (default) or .To activate the configuration, confirm the settings.
For more information about InfiniBand, see
/usr/src/linux/Documentation/infiniband/ipoib.txt
.
Without having to perform the detailed firewall setup as described in
Book “Security and Hardening Guide”, Chapter 25 “Masquerading and Firewalls”, Section 25.4 “firewalld
”, you can determine the
basic firewall configuration for your device as part of the device setup.
Proceed as follows:
Open the YaST
› module. In the tab, select a card from the list of detected cards and click .Enter the
tab of the dialog.Determine the
to which your interface should be assigned. The following options are available:This option is available only if the firewall is disabled and the firewall does not run. Only use this option if your machine is part of a greater network that is protected by an outer firewall.
This option is available only if the firewall is enabled. The
firewall is running and the interface is automatically assigned to a
firewall zone. The zone which contains the keyword
any
or the external zone will be used for such an
interface.
The firewall is running, but does not enforce any rules to protect this interface. Use this option if your machine is part of a greater network that is protected by an outer firewall. It is also useful for the interfaces connected to the internal network, when the machine has more network interfaces.
A demilitarized zone is an additional line of defense in front of an internal network and the (hostile) Internet. Hosts assigned to this zone can be reached from the internal network and from the Internet, but cannot access the internal network.
The firewall is running on this interface and fully protects it against other—presumably hostile—network traffic. This is the default option.
To activate the configuration, confirm the settings.
If a network card is not detected correctly, the card is not included in the list of detected cards. If you are sure that your system includes a driver for your card, you can configure it manually. You can also configure special network device types, such as bridge, bond, TUN or TAP. To configure an undetected network card (or a special device) proceed as follows:
In the
› › dialog in YaST click .In the
dialog, set the of the interface from the available options and . If the network card is a USB device, activate the respective check box and exit this dialog with . Otherwise, you can define the kernel to be used for the card and its , if necessary.
In ethtool
options used by ifup
for
the interface. For information about available options, see the
ethtool
manual page.
If the option string starts with a
-
(for example, -K
INTERFACE_NAME rx on
), the second
word in the string is replaced with the current interface name. Otherwise
(for example, autoneg off speed 10
)
ifup
adds -s
INTERFACE_NAME
to the beginning.
Click
.Configure any needed options, such as the IP address, device activation or firewall zone for the interface in the Section 13.4.1.2, “Changing the Configuration of a Network Card”.
, , and tabs. For more information about the configuration options, seeIf you selected
as the device type of the interface, configure the wireless connection in the next dialog.To activate the new network configuration, confirm the settings.
If you did not change the network configuration during installation and the Ethernet card was already available, a host name was automatically generated for your computer and DHCP was activated. The same applies to the name service information your host needs to integrate into a network environment. If DHCP is used for network address setup, the list of domain name servers is automatically filled with the appropriate data. If a static setup is preferred, set these values manually.
To change the name of your computer and adjust the name server search list, proceed as follows:
Go to the
› tab in the module in YaST.Enter the
. Note that the host name is global and applies to all network interfaces.If you are using DHCP to get an IP address, the host name of your computer will be automatically set by the DHCP server. You should disable this behavior if you connect to different networks, because they may assign different host names and changing the host name at runtime may confuse the graphical desktop. To disable using DHCP to get an IP address deactivate
.
127.0.0.2
(loopback) IP address in
/etc/hosts
. This is a useful option if you want to
have the host name resolvable at all times, even without active network.
In /run/netconfig/resolv.conf
file) is modified.
If the netconfig
script which
merges the data defined statically (with YaST or in the configuration
files) with data obtained dynamically (from the DHCP client or
NetworkManager). This default policy is usually sufficient.
If the netconfig
is not allowed to modify the
/run/netconfig/resolv.conf
file. However, this file can be
edited manually.
If the eth* ppp?
will
first target all eth and then all ppp0-ppp9 interfaces. There are two
special policy values that indicate how to apply the static settings
defined in the /etc/sysconfig/network/config
file:
STATIC
The static settings need to be merged together with the dynamic settings.
STATIC_FALLBACK
The static settings are used only when no dynamic configuration is available.
For more information, see the man page of netconfig
(8)
(man 8 netconfig
).
Enter the
and fill in the list. Name servers must be specified by IP addresses, such as 192.168.1.116, not by host names. Names specified in the tab are domain names used for resolving host names without a specified domain. If more than one is used, separate domains with commas or white space.To activate the configuration, confirm the settings.
It is also possible to edit the host name using YaST from the command
line. The changes made by YaST take effect immediately (which is not the
case when editing the /etc/HOSTNAME
file manually). To
change the host name, use the following command:
root #
yast dns edit hostname=HOSTNAME
To change the name servers, use the following commands:
root #
yast dns edit nameserver1=192.168.1.116root #
yast dns edit nameserver2=192.168.1.117root #
yast dns edit nameserver3=192.168.1.118
To make your machine communicate with other machines and other networks, routing information must be given to make network traffic take the correct path. If DHCP is used, this information is automatically provided. If a static setup is used, this data must be added manually.
In YaST go to
› .Enter the IP address of the
(IPv4 and IPv6 if necessary). The default gateway matches every possible destination, but if a routing table entry exists that matches the required address, this will be used instead of the default route via the Default Gateway.
More entries can be entered in the -
. To
enter a default gateway into the table, use default
in
the field.
If more default routes are used, it is possible to specify the metric
option to determine which route has a higher priority. To specify the
metric option, enter - metric
NUMBER
in
. The route with the highest metric is used as
default. If the network device is disconnected, its route will be
removed and the next one will be used. However, the current kernel does
not use metric in static routing, only routing daemons like
multipathd
do.
If the system is a router, enable
and in the as needed.To activate the configuration, confirm the settings.
NetworkManager is the ideal solution for laptops and other portable computers. With NetworkManager, you do not need to worry about configuring network interfaces and switching between networks when you are moving.
wicked
#Edit source
However, NetworkManager is not a suitable solution for all cases, so you can
still choose between the wicked
controlled method for
managing network connections and NetworkManager. If you want to manage your
network connection with NetworkManager, enable NetworkManager in the YaST Network
Settings module as described in Section 28.2, “Enabling or Disabling NetworkManager” and
configure your network connections with NetworkManager. For a list of use cases
and a detailed description of how to configure and use NetworkManager, refer to
Chapter 28, Using NetworkManager.
Some differences between wicked and NetworkManager:
root
Privileges
If you use NetworkManager for network setup, you can easily switch, stop or
start your network connection at any time from within your desktop
environment using an applet. NetworkManager also makes it possible to change
and configure wireless card connections without requiring
root
privileges. For this reason, NetworkManager is the ideal
solution for a mobile workstation.
wicked
also provides some ways to switch, stop or
start the connection with or without user intervention, like
user-managed devices. However, this always requires root
privileges to change or configure a network device. This is often a
problem for mobile computing, where it is not possible to preconfigure
all the connection possibilities.
Both wicked
and NetworkManager can handle network
connections with a wireless network (with WEP, WPA-PSK, and
WPA-Enterprise access) and wired networks using DHCP and static
configuration. They also support connection through dial-up and VPN.
With NetworkManager you can also connect a mobile broadband (3G) modem
or set up a DSL connection, which is not possible with the traditional
configuration.
NetworkManager tries to keep your computer connected at all times using the
best connection available. If the network cable is accidentally
disconnected, it tries to reconnect. It can find the network with the
best signal strength from the list of your wireless connections and
automatically use it to connect. To get the same functionality with
wicked
, more configuration effort is required.
The individual network connection settings created with NetworkManager are
stored in configuration profiles. The system
connections configured with either NetworkManager or YaST are saved in
/etc/NetworkManager/system-connections/*
or in
/etc/sysconfig/network/ifcfg-*
. For GNOME, all
user-defined connections are stored in GConf.
In case no profile is configured, NetworkManager automatically creates one and
names it Auto $INTERFACE-NAME
. That is made in an
attempt to work without any configuration for as many cases as (securely)
possible. If the automatically created profiles do not suit your needs,
use the network connection configuration dialogs provided by GNOME to
modify them as desired. For more information, see
Section 28.3, “Configuring Network Connections”.
On centrally administered machines, certain NetworkManager features can be controlled or disabled with PolKit, for example if a user is allowed to modify administrator defined connections or if a user is allowed to define their own network configurations. To view or change the respective NetworkManager policies, start the graphical Book “Security and Hardening Guide”, Chapter 19 “Authorization with PolKit”.
tool for PolKit. In the tree on the left side, find them below the entry. For an introduction to PolKit and details on how to use it, refer toManual configuration of the network software should be the last alternative. Using YaST is recommended. However, this background information about the network configuration can also assist your work with YaST.
wicked
Network Configuration #Edit source
The tool and library called wicked
provides a new
framework for network configuration.
One of the challenges with traditional network interface management is that different layers of network management get jumbled together into one single script, or at most two different scripts. These scripts interact with each other in a way that is not well defined. This leads to unpredictable issues, obscure constraints and conventions, etc. Several layers of special hacks for a variety of different scenarios increase the maintenance burden. Address configuration protocols are being used that are implemented via daemons like dhcpcd, which interact rather poorly with the rest of the infrastructure. Funky interface naming schemes that require heavy udev support are introduced to achieve persistent identification of interfaces.
The idea of wicked is to decompose the problem in several ways. None of them is entirely novel, but trying to put ideas from different projects together is hopefully going to create a better solution overall.
One approach is to use a client/server model. This allows wicked to define standardized facilities for things like address configuration that are well integrated with the overall framework. For example, using a specific address configuration, the administrator may request that an interface should be configured via DHCP or IPv4 zeroconf. In this case, the address configuration service simply obtains the lease from its server and passes it on to the wicked server process that installs the requested addresses and routes.
The other approach to decomposing the problem is to enforce the layering aspect. For any type of network interface, it is possible to define a dbus service that configures the network interface's device layer—a VLAN, a bridge, a bonding, or a paravirtualized device. Common functionality, such as address configuration, is implemented by joint services that are layered on top of these device specific services without having to implement them specifically.
The wicked framework implements these two aspects by using a variety of dbus services, which get attached to a network interface depending on its type. Here is a rough overview of the current object hierarchy in wicked.
Each network interface is represented via a child object of
/org/opensuse/Network/Interfaces
. The name of the
child object is given by its ifindex. For example, the loopback interface,
which usually gets ifindex 1, is
/org/opensuse/Network/Interfaces/1
, the first
Ethernet interface registered is
/org/opensuse/Network/Interfaces/2
.
Each network interface has a “class” associated with it, which
is used to select the dbus interfaces it supports. By default, each network
interface is of class netif
, and
wickedd
will automatically
attach all interfaces compatible with this class. In the current
implementation, this includes the following interfaces:
Generic network interface functions, such as taking the link up or down, assigning an MTU, etc.
Address configuration services for DHCP, IPv4 zeroconf, etc.
Beyond this, network interfaces may require or offer special configuration
mechanisms. For an Ethernet device, for example, you should be able to
control the link speed, offloading of checksumming, etc. To achieve this,
Ethernet devices have a class of their own, called
netif-ethernet
, which is a subclass of
netif
. As a consequence, the dbus interfaces assigned to
an Ethernet interface include all the services listed above, plus the
org.opensuse.Network.Ethernet
service available only to objects belonging to the netif-ethernet
class.
Similarly, there exist classes for interface types like bridges, VLANs, bonds, or infinibands.
How do you interact with an interface like VLAN (which is really a virtual network interface that
sits on top of an Ethernet device) that needs to be created
first? For this, wicked defines factory
interfaces, such as
org.opensuse.Network.VLAN.Factory
. Such a factory
interface offers a single function that lets you create an interface of the
requested type. These factory interfaces are attached to the
/org/opensuse/Network/Interfaces
list node.
wicked
Architecture and Features #Edit source
The wicked
service comprises several parts as depicted
in Figure 13.4, “wicked
architecture”.
wicked
architecture #
wicked
currently supports the following:
Configuration file back-ends to parse SUSE style
/etc/sysconfig/network
files.
An internal configuration back-end to represent network interface configuration in XML.
Bring up and shutdown of “normal” network interfaces such as Ethernet or InfiniBand, VLAN, bridge, bonds, tun, tap, dummy, macvlan, macvtap, hsi, qeth, iucv, and wireless (currently limited to one wpa-psk/eap network) devices.
A built-in DHCPv4 client and a built-in DHCPv6 client.
The nanny daemon (enabled by default) helps to automatically bring up configured interfaces when the device is available (interface hotplugging) and set up the IP configuration when a link (carrier) is detected. See Section 13.6.1.3, “Nanny” for more information.
wicked
was implemented as a group of DBus services
that are integrated with systemd. So the usual
systemctl
commands will apply to
wicked
.
wicked
#Edit source
On openSUSE Leap, wicked
runs by default on desktop or
server hardware. On mobile hardware NetworkManager runs by default. If you want to
check what is currently enabled and whether it is running, call:
systemctl status network
If wicked
is enabled, you will see something along these
lines:
wicked.service - wicked managed network interfaces Loaded: loaded (/usr/lib/systemd/system/wicked.service; enabled) ...
In case something different is running (for example, NetworkManager) and you want to
switch to wicked
, first stop what is running and then
enable wicked
:
systemctl is-active network && \ systemctl stop network systemctl enable --force wicked
This enables the wicked services, creates the
network.service
to wicked.service
alias link, and starts the network at the next boot.
Starting the server process:
systemctl start wickedd
This starts wickedd
(the main server) and associated
supplicants:
/usr/lib/wicked/bin/wickedd-auto4 --systemd --foreground /usr/lib/wicked/bin/wickedd-dhcp4 --systemd --foreground /usr/lib/wicked/bin/wickedd-dhcp6 --systemd --foreground /usr/sbin/wickedd --systemd --foreground /usr/sbin/wickedd-nanny --systemd --foreground
Then bringing up the network:
systemctl start wicked
Alternatively use the network.service
alias:
systemctl start network
These commands are using the default or system configuration sources as
defined in /etc/wicked/client.xml
.
To enable debugging, set WICKED_DEBUG
in
/etc/sysconfig/network/config
, for example:
WICKED_DEBUG="all"
Or, to omit some:
WICKED_DEBUG="all,-dbus,-objectmodel,-xpath,-xml"
Use the client utility to display interface information for all interfaces or the interface specified with IFNAME:
wicked show all wicked show IFNAME
In XML output:
wicked show-xml all wicked show-xml IFNAME
Bringing up one interface:
wicked ifup eth0 wicked ifup wlan0 ...
Because there is no configuration source specified, the wicked client
checks its default sources of configuration defined in
/etc/wicked/client.xml
:
firmware:
iSCSI Boot Firmware Table (iBFT)
compat:
ifcfg
files—implemented for compatibility
Whatever wicked
gets from those sources for a given
interface is applied. The intended order of importance is
firmware
, then compat
—this may
be changed in the future.
For more information, see the wicked
man page.
Nanny is an event and policy driven daemon that is responsible for
asynchronous or unsolicited scenarios such as hotplugging devices. Thus the
nanny daemon helps with starting or restarting delayed or temporarily gone
devices. Nanny monitors device and link changes, and integrates new devices
defined by the current policy set. Nanny continues to set up even if
ifup
already exited because of specified timeout
constraints.
By default, the nanny daemon is active on the system. It is enabled in the
/etc/wicked/common.xml
configuration file:
<config> ... <use-nanny>true</use-nanny> </config>
This setting causes ifup and ifreload to apply a policy with the effective
configuration to the nanny daemon; then, nanny configures
wickedd
and thus ensures
hotplug support. It waits in the background for events or changes (such as
new devices or carrier on).
For bonds and bridges, it may make sense to define the entire device topology in one file (ifcfg-bondX), and bring it up in one go. wicked then can bring up the whole configuration if you specify the top level interface names (of the bridge or bond):
wicked ifup br0
This command automatically sets up the bridge and its dependencies in the appropriate order without the need to list the dependencies (ports, etc.) separately.
To bring up multiple interfaces in one command:
wicked ifup bond0 br0 br1 br2
Or also all interfaces:
wicked ifup all
When you need to use tunnels with Wicked, the TUNNEL_DEVICE
is used for this. It permits to specify an optional device name to bind
the tunnel to the device. The tunneled packets will only be routed via this
device.
For more information, refer to man 5 ifcfg-tunnel
.
With wicked
, there is no need to actually take down an
interface to reconfigure it (unless it is required by the kernel). For
example, to add another IP address or route to a statically configured
network interface, add the IP address to the interface definition, and do
another “ifup” operation. The server will try hard to update
only those settings that have changed. This applies to link-level options
such as the device MTU or the MAC address, and network-level settings, such
as addresses, routes, or even the address configuration mode (for example,
when moving from a static configuration to DHCP).
Things get tricky of course with virtual interfaces combining several real devices such as bridges or bonds. For bonded devices, it is not possible to change certain parameters while the device is up. Doing that will result in an error.
However, what should still work, is the act of adding or removing the child devices of a bond or bridge, or choosing a bond's primary interface.
wicked
is designed to be extensible with shell scripts.
These extensions can be defined in the config.xml
file.
Currently, several classes of extensions are supported:
link configuration: these are scripts responsible for setting up a device's link layer according to the configuration provided by the client, and for tearing it down again.
address configuration: these are scripts responsible for managing a
device's address configuration. Usually address configuration and DHCP
are managed by wicked
itself, but can be implemented
by means of extensions.
firewall extension: these scripts can apply firewall rules.
Typically, extensions have a start and a stop command, an optional “pid file”, and a set of environment variables that get passed to the script.
To illustrate how this is supposed to work, look at a firewall extension
defined in etc/server.xml
:
<dbus-service interface="org.opensuse.Network.Firewall"> <action name="firewallUp" command="/etc/wicked/extensions/firewall up"/> <action name="firewallDown" command="/etc/wicked/extensions/firewall down"/> <!-- default environment for all calls to this extension script --> <putenv name="WICKED_OBJECT_PATH" value="$object-path"/> <putenv name="WICKED_INTERFACE_NAME" value="$property:name"/> <putenv name="WICKED_INTERFACE_INDEX" value="$property:index"/> </dbus-service>
The extension is attached to the
<dbus-service>
tag and defines commands to execute for the actions of this interface.
Further, the declaration can define and initialize environment variables
passed to the actions.
You can extend the handling of configuration files with scripts as well.
For example, DNS updates from leases are ultimately handled by the
extensions/resolver
script, with behavior configured
in server.xml
:
<system-updater name="resolver"> <action name="backup" command="/etc/wicked/extensions/resolver backup"/> <action name="restore" command="/etc/wicked/extensions/resolver restore"/> <action name="install" command="/etc/wicked/extensions/resolver install"/> <action name="remove" command="/etc/wicked/extensions/resolver remove"/> </system-updater>
When an update arrives in wickedd
, the system
updater routines parse the lease and call the appropriate commands
(backup
, install
, etc.) in the
resolver script. This in turn configures the DNS settings using
/sbin/netconfig
, or by manually writing
/run/netconfig/resolv.conf
as a fallback.
This section provides an overview of the network configuration files and explains their purpose and the format used.
/etc/wicked/common.xml
#Edit source
The /etc/wicked/common.xml
file contains common
definitions that should be used by all applications. It is sourced/included
by the other configuration files in this directory. Although you can use
this file to enable debugging across all
wicked
components, we recommend to use the file
/etc/wicked/local.xml
for this purpose. After applying
maintenance updates you might lose your changes as the
/etc/wicked/common.xml
might be overwritten. The
/etc/wicked/common.xml
file includes the
/etc/wicked/local.xml
in the default installation, thus
you typically do not need to modify the
/etc/wicked/common.xml
.
In case you want to disable nanny
by setting the
<use-nanny>
to false
, restart
the wickedd.service
and then run the following command to
apply all configurations and policies:
tux >
sudo
wicked ifup all
The wickedd
, wicked
, or
nanny
programs try to read
/etc/wicked/common.xml
if their own configuration
files do not exist.
/etc/wicked/server.xml
#Edit source
The file /etc/wicked/server.xml
is read by the
wickedd
server process at start-up. The file stores
extensions to the /etc/wicked/common.xml
. On top of
that this file configures handling of a resolver and receiving information
from addrconf
supplicants, for example DHCP.
We recommend to add changes required to this file into a separate file
/etc/wicked/server-local.xml
, that gets included by
/etc/wicked/server.xml
. By using a separate file
you avoid overwriting of your changes during maintenance updates.
/etc/wicked/client.xml
#Edit source
The /etc/wicked/client.xml
is used by the
wicked
command. The file specifies the location of a
script used when discovering devices managed by ibft and configures
locations of network interface configurations.
We recommend to add changes required to this file into a separate file
/etc/wicked/client-local.xml
, that gets included by
/etc/wicked/server.xml
. By using a separate file
you avoid overwriting of your changes during maintenance updates.
/etc/wicked/nanny.xml
#Edit source
The /etc/wicked/nanny.xml
configures types of link
layers. We recommend to add specific configuration into a separate file:
/etc/wicked/nanny-local.xml
to avoid losing the changes
during maintenance updates.
/etc/sysconfig/network/ifcfg-*
#Edit sourceThese files contain the traditional configurations for network interfaces. In openSUSE prior to Leap, this was the only supported format besides iBFT firmware.
wicked
and the ifcfg-*
Files
wicked
reads these files if you specify the
compat:
prefix. According to the openSUSE Leap default
configuration in /etc/wicked/client.xml
,
wicked
tries these files before the XML configuration
files in /etc/wicked/ifconfig
.
The --ifconfig
switch is provided mostly for testing only.
If specified, default configuration sources defined in
/etc/wicked/ifconfig
are not applied.
The ifcfg-*
files include information such as the start
mode and the IP address. Possible parameters are described in the manual
page of ifup
. Additionally, most variables from the
dhcp
and wireless
files can be
used in the ifcfg-*
files if a general setting should
be used for only one interface. However, most of the
/etc/sysconfig/network/config
variables are global and
cannot be overridden in ifcfg-files. For example,
NETCONFIG_*
variables are global.
For configuring macvlan
and
macvtab
interfaces, see the
ifcfg-macvlan
and
ifcfg-macvtap
man pages. For example, for a macvlan
interface provide a ifcfg-macvlan0
with settings as
follows:
STARTMODE='auto' MACVLAN_DEVICE='eth0' #MACVLAN_MODE='vepa' #LLADDR=02:03:04:05:06:aa
For ifcfg.template
, see
Section 13.6.2.6, “/etc/sysconfig/network/config
, /etc/sysconfig/network/dhcp
, and /etc/sysconfig/network/wireless
”.
/etc/sysconfig/network/config
, /etc/sysconfig/network/dhcp
, and /etc/sysconfig/network/wireless
#Edit source
The file config
contains general settings for the
behavior of ifup
, ifdown
and
ifstatus
. dhcp
contains settings for
DHCP and wireless
for wireless LAN cards. The variables
in all three configuration files are commented. Some variables from
/etc/sysconfig/network/config
can also be used in
ifcfg-*
files, where they are given a higher priority.
The /etc/sysconfig/network/ifcfg.template
file lists
variables that can be specified in a per interface scope. However, most of
the /etc/sysconfig/network/config
variables are global
and cannot be overridden in ifcfg-files. For example,
NETWORKMANAGER
or
NETCONFIG_*
variables are global.
In openSUSE prior to Leap, DHCPv6 used to work even on networks where IPv6 Router Advertisements (RAs) were not configured properly. Starting with openSUSE Leap, DHCPv6 will correctly require that at least one of the routers on the network sends out RAs that indicate that this network is managed by DHCPv6.
For networks where the router cannot be configured correctly, the ifcfg
option allows the user to override this
behavior by specifying DHCLIENT6_MODE='managed'
in the
ifcfg
file.
You can also activate this workaround with a boot parameter in the
installation system:
ifcfg=eth0=dhcp6,DHCLIENT6_MODE=managed
/etc/sysconfig/network/routes
and /etc/sysconfig/network/ifroute-*
#Edit source
The static routing of TCP/IP packets is determined by the
/etc/sysconfig/network/routes
and
/etc/sysconfig/network/ifroute-*
files. All the static
routes required by the various system tasks can be specified in
/etc/sysconfig/network/routes
: routes to a host, routes
to a host via a gateway and routes to a network. For each interface that
needs individual routing, define an additional configuration file:
/etc/sysconfig/network/ifroute-*
. Replace the wild card
(*
) with the name of the interface. The entries in the
routing configuration files look like this:
# Destination Gateway Netmask Interface Options
The route's destination is in the first column. This column may contain the
IP address of a network or host or, in the case of
reachable name servers, the fully qualified network or
host name. The network should be written in CIDR notation (address with the
associated routing prefix-length) such as 10.10.0.0/16 for IPv4 or fc00::/7
for IPv6 routes. The keyword default
indicates that the
route is the default gateway in the same address family as the gateway. For
devices without a gateway use explicit 0.0.0.0/0 or ::/0 destinations.
The second column contains the default gateway or a gateway through which a host or network can be accessed.
The third column is deprecated; it used to contain the IPv4 netmask of the
destination. For IPv6 routes, the default route, or when using a
prefix-length (CIDR notation) in the first column, enter a dash
(-
) here.
The fourth column contains the name of the interface. If you leave it empty
using a dash (-
), it can cause unintended behavior in
/etc/sysconfig/network/routes
. For more information,
see the routes
man page.
An (optional) fifth column can be used to specify special options. For
details, see the routes
man page.
# --- IPv4 routes in CIDR prefix notation: # Destination [Gateway] - Interface 127.0.0.0/8 - - lo 204.127.235.0/24 - - eth0 default 204.127.235.41 - eth0 207.68.156.51/32 207.68.145.45 - eth1 192.168.0.0/16 207.68.156.51 - eth1 # --- IPv4 routes in deprecated netmask notation" # Destination [Dummy/Gateway] Netmask Interface # 127.0.0.0 0.0.0.0 255.255.255.0 lo 204.127.235.0 0.0.0.0 255.255.255.0 eth0 default 204.127.235.41 0.0.0.0 eth0 207.68.156.51 207.68.145.45 255.255.255.255 eth1 192.168.0.0 207.68.156.51 255.255.0.0 eth1 # --- IPv6 routes are always using CIDR notation: # Destination [Gateway] - Interface 2001:DB8:100::/64 - - eth0 2001:DB8:100::/32 fe80::216:3eff:fe6d:c042 - eth0
/var/run/netconfig/resolv.conf
#Edit source
The domain to which the host belongs is specified in
/var/run/netconfig/resolv.conf
(keyword
search
). Up to six domains with a total of 256
characters can be specified with the search
option.
When resolving a name that is not fully qualified, an attempt is made to
generate one by attaching the individual search
entries. Up to three name servers can be specified with the
nameserver
option, each on a line of its own.
Comments are preceded by hash mark or semicolon signs (#
or ;
). As an example, see
Example 13.6, “/var/run/netconfig/resolv.conf
”.
However, /etc/resolv.conf
should not be edited by
hand. It is generated by the netconfig
script and is a
symbolic link to /run/netconfig/resolv.conf
.
To define static DNS configuration without using YaST, edit the
appropriate variables manually in the
/etc/sysconfig/network/config
file:
NETCONFIG_DNS_STATIC_SEARCHLIST
list of DNS domain names used for host name lookup
NETCONFIG_DNS_STATIC_SERVERS
list of name server IP addresses to use for host name lookup
NETCONFIG_DNS_FORWARDER
the name of the DNS forwarder that needs to be configured, for example
bind
or resolver
NETCONFIG_DNS_RESOLVER_OPTIONS
arbitrary options that will be written to
/var/run/netconfig/resolv.conf
, for example:
debug attempts:1 timeout:10
For more information, see the resolv.conf
man page.
NETCONFIG_DNS_RESOLVER_SORTLIST
list of up to 10 items, for example:
130.155.160.0/255.255.240.0 130.155.0.0
For more information, see the resolv.conf
man
page.
To disable DNS configuration using netconfig, set
NETCONFIG_DNS_POLICY=''
. For more information about
netconfig
, see the netconfig(8)
man page (man 8 netconfig
).
/var/run/netconfig/resolv.conf
## Our domain search example.com # # We use dns.example.com (192.168.1.116) as nameserver nameserver 192.168.1.116
/sbin/netconfig
#Edit source
netconfig
is a modular tool to manage additional network
configuration settings. It merges statically defined settings with settings
provided by autoconfiguration mechanisms as DHCP or PPP according to a
predefined policy. The required changes are applied to the system by calling
the netconfig modules that are responsible for modifying a configuration
file and restarting a service or a similar action.
netconfig
recognizes three main actions. The
netconfig modify
and netconfig remove
commands are used by daemons such as DHCP or PPP to provide or remove
settings to netconfig. Only the netconfig update
command
is available for the user:
modify
The netconfig modify
command modifies the current
interface and service specific dynamic settings and updates the network
configuration. Netconfig reads settings from standard input or from a
file specified with the --lease-file
FILENAME
option and internally stores
them until a system reboot (or the next modify or remove action). Already
existing settings for the same interface and service combination are
overwritten. The interface is specified by the -i
INTERFACE_NAME
parameter. The service
is specified by the -s
SERVICE_NAME
parameter.
remove
The netconfig remove
command removes the dynamic
settings provided by an editing action for the specified interface
and service combination and updates the network configuration. The
interface is specified by the -i
INTERFACE_NAME
parameter. The service
is specified by the -s
SERVICE_NAME
parameter.
update
The netconfig update
command updates the network
configuration using current settings. This is useful when the policy or
the static configuration has changed. Use the -m
MODULE_TYPE
parameter to
update a specified service only (dns
,
nis
, or ntp
).
The netconfig policy and the static configuration settings are defined
either manually or using YaST in the
/etc/sysconfig/network/config
file. The dynamic
configuration settings provided by autoconfiguration tools such as DHCP or
PPP are delivered directly by these tools with the netconfig
modify
and netconfig remove
actions.
When NetworkManager is enabled, netconfig (in policy mode auto
)
uses only NetworkManager settings, ignoring settings from any other interfaces
configured using the traditional ifup method. If NetworkManager does not provide any
setting, static settings are used as a fallback. A mixed usage of NetworkManager and
the wicked
method is not supported.
For more information about netconfig
, see man 8
netconfig
.
/etc/hosts
#Edit source
In this file, shown in Example 13.7, “/etc/hosts
”, IP addresses
are assigned to host names. If no name server is implemented, all hosts to
which an IP connection will be set up must be listed here. For each host,
enter a line consisting of the IP address, the fully qualified host name,
and the host name into the file. The IP address must be at the beginning of
the line and the entries separated by blanks and tabs. Comments are always
preceded by the #
sign.
/etc/hosts
#127.0.0.1 localhost 192.168.2.100 jupiter.example.com jupiter 192.168.2.101 venus.example.com venus
/etc/networks
#Edit source
Here, network names are converted to network addresses. The format is
similar to that of the hosts
file, except the network
names precede the addresses. See Example 13.8, “/etc/networks
”.
/etc/networks
#loopback 127.0.0.0 localnet 192.168.0.0
/etc/host.conf
#Edit source
Name resolution—the translation of host and network names via the
resolver library—is controlled by this file. This
file is only used for programs linked to libc4 or libc5. For current glibc
programs, refer to the settings in /etc/nsswitch.conf
.
Each parameter must always be entered on a separate line. Comments are
preceded by a #
sign.
Table 13.2, “Parameters for /etc/host.conf” shows the parameters available. A
sample /etc/host.conf
is shown in
Example 13.9, “/etc/host.conf
”.
order hosts, bind |
Specifies in which order the services are accessed for the name resolution. Available arguments are (separated by blank spaces or commas): |
hosts: searches the
| |
bind: accesses a name server | |
nis: uses NIS | |
multi on/off |
Defines if a host entered in |
nospoof on spoofalert on/off |
These parameters influence the name server spoofing but do not exert any influence on the network configuration. |
trim domainname |
The specified domain name is separated from the host name after host
name resolution (as long as the host name includes the domain name).
This option is useful only if names from the local domain are in the
|
/etc/host.conf
## We have named running order hosts bind # Allow multiple address multi on
/etc/nsswitch.conf
#Edit source
The introduction of the GNU C Library 2.0 was accompanied by the
introduction of the Name Service Switch (NSS). Refer to
the nsswitch.conf(5)
man page and The GNU
C Library Reference Manual for details.
The order for queries is defined in the file
/etc/nsswitch.conf
. A sample
nsswitch.conf
is shown in
Example 13.10, “/etc/nsswitch.conf
”. Comments are preceded by
#
signs. In this example, the entry under the
hosts
database means that a request is sent to
/etc/hosts
(files
) via
DNS (see Chapter 19, The Domain Name System).
/etc/nsswitch.conf
#passwd: compat group: compat hosts: files dns networks: files dns services: db files protocols: db files rpc: files ethers: files netmasks: files netgroup: files nis publickey: files bootparams: files automount: files nis aliases: files nis shadow: compat
The “databases” available over NSS are listed in Table 13.3, “Databases Available via /etc/nsswitch.conf”. The configuration options for NSS databases are listed in Table 13.4, “Configuration Options for NSS “Databases””.
|
Mail aliases implemented by |
|
Ethernet addresses. |
|
List of networks and their subnet masks. Only needed, if you use subnetting. |
|
User groups used by |
|
Host names and IP addresses, used by |
|
Valid host and user lists in the network for controlling access
permissions; see the |
|
Network names and addresses, used by |
|
Public and secret keys for Secure_RPC used by NFS and NIS+. |
|
User passwords, used by |
|
Network protocols, used by |
|
Remote procedure call names and addresses, used by
|
|
Network services, used by |
|
Shadow passwords of users, used by |
|
directly access files, for example, |
|
access via a database |
|
NIS, see also Book “Security and Hardening Guide”, Chapter 4 “Using NIS” |
|
can only be used as an extension for |
|
can only be used as an extension for |
/etc/nscd.conf
#Edit source
This file is used to configure nscd (name service cache daemon). See the
nscd(8)
and nscd.conf(5)
man pages. By default, the system entries of passwd
,
groups
and hosts
are cached by nscd. This is important for the
performance of directory services, like NIS and LDAP, because otherwise the
network connection needs to be used for every access to names, groups or
hosts.
If the caching for passwd
is activated, it usually takes
about fifteen seconds until a newly added local user is recognized. Reduce
this waiting time by restarting nscd with:
tux >
sudo
systemctl restart nscd
/etc/HOSTNAME
#Edit source
/etc/HOSTNAME
contains the fully qualified host name
(FQHN). The fully qualified host name is the host name with the domain name
attached. This file must contain only one line (in which the host name is
set). It is read while the machine is booting.
Before you write your configuration to the configuration files, you can test
it. To set up a test configuration, use the ip
command.
To test the connection, use the ping
command.
The command ip
changes the network configuration directly
without saving it in the configuration file. Unless you enter your
configuration in the correct configuration files, the changed network
configuration is lost on reboot.
ifconfig
and route
Are Obsolete
The ifconfig
and route
tools are
obsolete. Use ip
instead. ifconfig
,
for example, limits interface names to 9 characters.
ip
#Edit source
ip
is a tool to show and configure network devices,
routing, policy routing, and tunnels.
ip
is a very complex tool. Its common syntax is
ip
OPTIONS
OBJECT
COMMAND
. You can work with the
following objects:
This object represents a network device.
This object represents the IP address of device.
This object represents an ARP or NDISC cache entry.
This object represents the routing table entry.
This object represents a rule in the routing policy database.
This object represents a multicast address.
This object represents a multicast routing cache entry.
This object represents a tunnel over IP.
If no command is given, the default command is used (usually
list
).
Change the state of a device with the command:
tux >
sudo
ip link set DEV_NAME
For example, to deactivate device eth0, enter
tux >
sudo
ip link set eth0 down
To activate it again, use
tux >
sudo
ip link set eth0 up
If you deactivate a device with
tux >
sudo
ip link set DEV_NAME down
it disables the network interface on a software level.
If you want to simulate losing the link as if the Ethernet cable is unplugged or the connected switch is turned off, run
tux >
sudo
ip link set DEV_NAME carrier off
For example, while ip link set
DEV_NAME down
drops all routes using
DEV_NAME, ip link set DEV carrier
off
does not. Be aware that carrier off
requires support from the network device driver.
To connect the device back to the physical network, run
tux >
sudo
ip link set DEV_NAME carrier on
After activating a device, you can configure it. To set the IP address, use
tux >
sudo
ip addr add IP_ADDRESS + dev DEV_NAME
For example, to set the address of the interface eth0 to 192.168.12.154/30
with standard broadcast (option brd
), enter
tux >
sudo
ip addr add 192.168.12.154/30 brd + dev eth0
To have a working connection, you must also configure the default gateway. To set a gateway for your system, enter
tux >
sudo
ip route add default via gateway_ip_address
To display all devices, use
tux >
sudo
ip link ls
To display the running interfaces only, use
tux >
sudo
ip link ls up
To print interface statistics for a device, enter
tux >
sudo
ip -s link ls DEV_NAME
To view additional useful information, specifically about virtual network devices, enter
tux >
sudo
ip -d link ls DEV_NAME
Moreover, to view network layer (IPv4, IPv6) addresses of your devices, enter
tux >
sudo
ip addr
In the output, you can find information about MAC addresses of your devices. To show all routes, use
tux >
sudo
ip route show
For more information about using ip
, enter
ip
help
or see the
man 8 ip
manual page. The help
option
is also available for all ip
subcommands, such as:
tux >
sudo
ip addr help
Find the ip
manual in
/usr/share/doc/packages/iproute2/ip-cref.pdf
.
The ping
command is the standard tool for testing
whether a TCP/IP connection works. It uses the ICMP protocol to send a
small data packet, ECHO_REQUEST datagram, to the destination host,
requesting an immediate reply. If this works, ping
displays a message to that effect. This indicates that the network link is
functioning.
ping
does more than only test the function of the
connection between two computers: it also provides some basic information
about the quality of the connection. In
Example 13.11, “Output of the Command ping”, you can see an example of the
ping
output. The second-to-last line contains
information about the number of transmitted packets, packet loss, and total
time of ping
running.
As the destination, you can use a host name or IP address, for example,
ping
example.com
or
ping
192.168.3.100
. The program sends
packets until you press
Ctrl–C.
If you only need to check the functionality of the connection, you can
limit the number of the packets with the -c
option. For
example to limit ping to three packets, enter
ping
-c 3 example.com
.
ping -c 3 example.com PING example.com (192.168.3.100) 56(84) bytes of data. 64 bytes from example.com (192.168.3.100): icmp_seq=1 ttl=49 time=188 ms 64 bytes from example.com (192.168.3.100): icmp_seq=2 ttl=49 time=184 ms 64 bytes from example.com (192.168.3.100): icmp_seq=3 ttl=49 time=183 ms --- example.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2007ms rtt min/avg/max/mdev = 183.417/185.447/188.259/2.052 ms
The default interval between two packets is one second. To change the
interval, ping provides the option -i
. For example, to
increase the ping interval to ten seconds, enter
ping
-i 10 example.com
.
In a system with multiple network devices, it is sometimes useful to send
the ping through a specific interface address. To do so, use the
-I
option with the name of the selected device, for
example, ping
-I wlan1
example.com
.
For more options and information about using ping, enter
ping
-h
or see the
ping (8)
man page.
For IPv6 addresses use the ping6
command. Note, to ping
link-local addresses, you must specify the interface with
-I
. The following command works, if the address is
reachable via eth1
:
ping6 -I eth1 fe80::117:21ff:feda:a425
Apart from the configuration files described above, there are also systemd
unit files and various scripts that load the network services while the
machine is booting. These are started when the system is switched to the
multi-user.target
target. Some of these unit files
and scripts are described in Some Unit Files and Start-Up Scripts for Network Programs. For
more information about systemd
, see
Chapter 10, The systemd
Daemon and for more information about the
systemd
targets, see the man page of
systemd.special
(man
systemd.special
).
network.target
network.target
is the systemd target for
networking, but its mean depends on the settings provided by the system
administrator.
For more information, see http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/.
multi-user.target
multi-user.target
is the systemd target for a
multiuser system with all required network services.
rpcbind
Starts the rpcbind utility that converts RPC program numbers to universal addresses. It is needed for RPC services, such as an NFS server.
ypserv
Starts the NIS server.
ypbind
Starts the NIS client.
/etc/init.d/nfsserver
Starts the NFS server.
/etc/init.d/postfix
Controls the postfix process.
A router is a networking device that delivers and receives data (network packets) to or from more than one network back and forth. You often use a router to connect your local network to the remote network (Internet) or to connect local network segments. With openSUSE Leap you can build a router with features such as NAT (Network Address Translation) or advanced firewalling.
The following are basic steps to turn openSUSE Leap into a router.
Enable forwarding, for example in
/etc/sysctl.d/50-router.conf
net.ipv4.conf.all.forwarding = 1 net.ipv6.conf.all.forwarding = 1
Then provide a static IPv4 and IPv6 IP setup for the interfaces. Enabling forwarding disables several mechanisms, for example IPv6 does not accept an IPv6 RA (router advertisement) anymore, which also prevents the creation of a default route.
In many situations (for example, when you can reach the same network via more than one interface, or when VPN usually is used and already on “normal multi-home hosts”), you must disable the IPv4 reverse path filter (this feature does not currently exist for IPv6):
net.ipv4.conf.all.rp_filter = 0
You can also filter with firewall settings instead.
To accept an IPv6 RA (from the router on an external, uplink, or ISP interface) and create a default (or also a more specific) IPv6 route again, set:
net.ipv6.conf.${ifname}.accept_ra = 2 net.ipv6.conf.${ifname}.autoconf = 0
(Note: “eth0.42
” needs to be written as
eth0/42
in a dot-separated sysfs path.)
More router behavior and forwarding dependencies are described in https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt.
To provide IPv6 on your internal (DMZ) interfaces, and announce yourself as
an IPv6 router and “autoconf networks” to the clients, install
and configure radvd
in
/etc/radvd.conf
, for example:
interface eth0 { IgnoreIfMissing on; # do not fail if interface missed AdvSendAdvert on; # enable sending RAs AdvManagedFlag on; # IPv6 addresses managed via DHCPv6 AdvOtherConfigFlag on; # DNS, NTP... only via DHCPv6 AdvDefaultLifetime 3600; # client default route lifetime of 1 hour prefix 2001:db8:0:1::/64 # (/64 is default and required for autoconf) { AdvAutonomous off; # Disable address autoconf (DHCPv6 only) AdvValidLifetime 3600; # prefix (autoconf addr) is valid 1 h AdvPreferredLifetime 1800; # prefix (autoconf addr) is prefered 1/2 h } }
Configure the firewall to masquerade traffic with NAT from the LAN into the WAN and to block inbound traffic on the WAN interface:
tux >
sudo
firewall-cmd
--permanent --zone=external --change-interface=WAN_INTERFACEtux >
sudo
firewall-cmd
--permanent --zone=external --add-masqueradetux >
sudo
firewall-cmd
--permanent --zone=internal --change-interface=LAN_INTERFACEtux >
sudo
firewall-cmd
--reload
For some systems, there is a desire to implement network connections that comply to more than the standard data security or availability requirements of a typical Ethernet device. In these cases, several Ethernet devices can be aggregated to a single bonding device.
The configuration of the bonding device is done by means of bonding module
options. The behavior is mainly affected by the mode of the bonding device.
By default, this is active-backup
which means
that a different slave device will become active if the active slave fails.
The following bonding modes are available:
Packets are transmitted in round-robin fashion from the first to the last available interface. Provides fault tolerance and load balancing.
Only one network interface is active. If it fails, a different interface becomes active. This setting is the default for openSUSE Leap. Provides fault tolerance.
Traffic is split between all available interfaces based on the following
policy: [(source MAC address XOR'd with destination MAC address
XOR packet type ID) modulo slave count]
Requires support from
the switch. Provides fault tolerance and load balancing.
All traffic is broadcast on all interfaces. Requires support from the switch. Provides fault tolerance.
Aggregates interfaces into groups that share the same speed and duplex
settings. Requires ethtool
support in the interface
drivers, and a switch that supports and is configured for IEEE 802.3ad
Dynamic link aggregation. Provides fault tolerance and load balancing.
Adaptive transmit load balancing. Requires ethtool
support in the interface drivers but not switch support. Provides fault
tolerance and load balancing.
Adaptive load balancing. Requires ethtool
support in
the interface drivers but not switch support. Provides fault tolerance and
load balancing.
For a more detailed description of the modes, see https://www.kernel.org/doc/Documentation/networking/bonding.txt.
Using bonding devices is only of interest for machines where you have multiple real network cards available. In most configurations, this means that you should use the bonding configuration only in Dom0. Only if you have multiple network cards assigned to a VM Guest system it may also be useful to set up the bond in a VM Guest.
To configure a bonding device, use the following procedure:
Run
› › .Use
and change the to . Proceed with .Select how to assign the IP address to the bonding device. Three methods are at your disposal:
No IP Address
Dynamic Address (with DHCP or Zeroconf)
Statically assigned IP Address
Use the method that is appropriate for your environment.
In the
tab, select the Ethernet devices that should be included into the bond by activating the related check box.Edit the
and choose a bonding mode.
Make sure that the parameter miimon=100
is added to the
. Without this parameter, the data
integrity is not checked regularly.
Click
and leave YaST with to create the device.In specific network environments (such as High Availability), there are cases when you need to replace a bonding slave interface with another one. The reason may be a constantly failing network device. The solution is to set up hotplugging of bonding slaves.
The bond is configured as usual (according to man 5
ifcfg-bonding
), for example:
ifcfg-bond0 STARTMODE='auto' # or 'onboot' BOOTPROTO='static' IPADDR='192.168.0.1/24' BONDING_MASTER='yes' BONDING_SLAVE_0='eth0' BONDING_SLAVE_1='eth1' BONDING_MODULE_OPTS='mode=active-backup miimon=100'
The slaves are specified with STARTMODE=hotplug
and
BOOTPROTO=none
:
ifcfg-eth0 STARTMODE='hotplug' BOOTPROTO='none' ifcfg-eth1 STARTMODE='hotplug' BOOTPROTO='none'
BOOTPROTO=none
uses the ethtool
options (when provided), but does not set the link up on ifup
eth0
. The reason is that the slave interface is controlled by the
bond master.
STARTMODE=hotplug
causes the slave interface to join the
bond automatically when it is available.
The udev
rules in
/etc/udev/rules.d/70-persistent-net.rules
need to be
changed to match the device by bus ID (udev KERNELS
keyword equal to "SysFS BusID" as visible in hwinfo
--netcard
) instead of by MAC address. This allows replacement of
defective hardware (a network card in the same slot but with a different
MAC) and prevents confusion when the bond changes the MAC address of all its
slaves.
For example:
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", KERNELS=="0000:00:19.0", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"
At boot time, the systemd network.service
does not
wait for the hotplug slaves, but for the bond to become ready, which
requires at least one available slave. When one of the slave interfaces gets
removed (unbind from NIC driver, rmmod
of the NIC driver
or true PCI hotplug remove) from the system, the kernel removes it from the
bond automatically. When a new card is added to the system (replacement of
the hardware in the slot), udev
renames it using
the bus-based persistent name rule to the name of the slave, and calls
ifup
for it. The ifup
call
automatically joins it into the bond.
The term “link aggregation” is the general term which describes combining (or aggregating) a network connection to provide a logical layer. Sometimes you find the terms “channel teaming”, “Ethernet bonding”, “port truncating”, etc. which are synonyms and refer to the same concept.
This concept is widely known as “bonding” and was originally integrated into the Linux kernel (see Section 13.8, “Setting Up Bonding Devices” for the original implementation). The term Network Teaming is used to refer to the new implementation of this concept.
The main difference between bonding and Network Teaming is that teaming supplies a set of small kernel modules responsible for providing an interface for teamd instances. Everything else is handled in user space. This is different from the original bonding implementation which contains all of its functionality exclusively in the kernel. For a comparison refer to Table 13.5, “Feature Comparison between Bonding and Team”.
Feature | Bonding | Team |
---|---|---|
broadcast, round-robin TX policy | yes | yes |
active-backup TX policy | yes | yes |
LACP (802.3ad) support | yes | yes |
hash-based TX policy | yes | yes |
user can set hash function | no | yes |
TX load-balancing support (TLB) | yes | yes |
TX load-balancing support for LACP | no | yes |
Ethtool link monitoring | yes | yes |
ARP link monitoring | yes | yes |
NS/NA (IPV6) link monitoring | no | yes |
RCU locking on TX/RX paths | no | yes |
port prio and stickiness | no | yes |
separate per-port link monitoring setup | no | yes |
multiple link monitoring setup | limited | yes |
VLAN support | yes | yes |
multiple device stacking | yes | yes |
Source: http://libteam.org/files/teamdev.pp.pdf |
Both implementations, bonding and Network Teaming, can be used in parallel. Network Teaming is an alternative to the existing bonding implementation. It does not replace bonding.
Network Teaming can be used for different use cases. The two most important use cases are explained later and involve:
Load balancing between different network devices.
Failover from one network device to another in case one of the devices should fail.
Currently, there is no YaST module to support creating a teaming device. You need to configure Network Teaming manually. The general procedure is shown below which can be applied for all your Network Teaming configurations:
Make sure you have all the necessary packages installed. Install the packages libteam-tools, libteamdctl0, and python-libteam.
Create a configuration file under
/etc/sysconfig/network/
. Usually it will be
ifcfg-team0
. If you need more than one Network Teaming
device, give them ascending numbers.
This configuration file contains several variables which are explained in
the man pages (see man ifcfg
and man
ifcfg-team
). An example configuration can be found in your
system in the file /etc/sysconfig/network/ifcfg.template
.
Remove the configuration files of the interfaces which will be used for the
teaming device (usually ifcfg-eth0
and
ifcfg-eth1
).
It is recommended to make a backup and remove both files. Wicked will re-create the configuration files with the necessary parameters for teaming.
Optionally, check if everything is included in Wicked's configuration file:
tux >
sudo
wicked show-config
Start the Network Teaming device team0
:
tux >
sudo
wicked ifup all team0
In case you need additional debug information, use the option
--debug all
after the all
subcommand.
Check the status of the Network Teaming device. This can be done by the following commands:
Get the state of the teamd instance from Wicked:
tux >
sudo
wicked ifstatus --verbose team0
Get the state of the entire instance:
tux >
sudo
teamdctl team0 state
Get the systemd state of the teamd instance:
tux >
sudo
systemctl status teamd@team0
Each of them shows a slightly different view depending on your needs.
In case you need to change something in the
ifcfg-team0
file afterward, reload its configuration
with:
tux >
sudo
wicked ifreload team0
Do not use systemctl
for starting or
stopping the teaming device! Instead, use the wicked
command as shown above.
To completely remove the team device, use this procedure: