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788f37c725
udevadm test-builtin can be very useful for testing .link files, so add a reference. Addresses issue #2406.
478 lines
17 KiB
XML
478 lines
17 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Tom Gundersen
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.link">
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<refentryinfo>
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<title>systemd.link</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Tom</firstname>
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<surname>Gundersen</surname>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.link</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.link</refname>
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<refpurpose>Network device configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename><replaceable>link</replaceable>.link</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>Network link configuration is performed by the
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<command>net_setup_link</command> udev builtin.</para>
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<para>The link files are read from the files located in the system
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network directory <filename>/usr/lib/systemd/network</filename>,
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the volatile runtime network directory
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<filename>/run/systemd/network</filename>, and the local
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administration network directory
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<filename>/etc/systemd/network</filename>. Link files must have
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the extension <filename>.link</filename>; other extensions are
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ignored. All link files are collectively sorted and processed in
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lexical order, regardless of the directories in which they live.
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However, files with identical filenames replace each other. Files
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in <filename>/etc</filename> have the highest priority, files in
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<filename>/run</filename> take precedence over files with the same
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name in <filename>/usr/lib</filename>. This can be used to
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override a system-supplied link file with a local file if needed.
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As a special case, an empty file (file size 0) or symlink with the
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same name pointing to <filename>/dev/null</filename> disables the
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configuration file entirely (it is "masked").</para>
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<para>The link file contains a <literal>[Match]</literal> section,
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which determines if a given link file may be applied to a given
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device, as well as a <literal>[Link]</literal> section specifying
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how the device should be configured. The first (in lexical order)
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of the link files that matches a given device is applied. Note
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that a default file <filename>99-default.link</filename> is
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shipped by the system, any user-supplied
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<filename>.link</filename> should hence have a lexically earlier
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name to be considered at all.</para>
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<para>See
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<citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for diagnosing problems with <filename>.link</filename> files.</para>
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</refsect1>
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<refsect1>
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<title>[Match] Section Options</title>
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<para>A link file is said to match a device if each of the entries
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in the <literal>[Match]</literal> section matches, or if the
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section is empty. The following keys are accepted:</para>
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<variablelist class='network-directives'>
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<varlistentry>
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<term><varname>MACAddress=</varname></term>
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<listitem>
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<para>The hardware address.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>OriginalName=</varname></term>
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<listitem>
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<para>A whitespace-separated list of shell-style globs matching
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the device name, as exposed by the udev property
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"INTERFACE". This can not be used to match on names that have
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already been changed from userspace. Caution is advised when matching on
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kernel-assigned names, as they are known to be unstable
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between reboots.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Path=</varname></term>
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<listitem>
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<para>A whitespace-separated list of shell-style globs matching
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the persistent path, as exposed by the udev property
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<literal>ID_PATH</literal>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Driver=</varname></term>
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<listitem>
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<para>A whitespace-separated list of shell-style globs matching
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the driver currently bound to the device,
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as exposed by the udev property <literal>DRIVER</literal>
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of its parent device, or if that is not set, the
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driver as exposed by <literal>ethtool -i</literal>
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of the device itself.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Type=</varname></term>
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<listitem>
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<para>A whitespace-separated list of shell-style globs matching
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the device type, as exposed by the udev
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property <literal>DEVTYPE</literal>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Host=</varname></term>
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<listitem>
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<para>Matches against the hostname or machine
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ID of the host. See <literal>ConditionHost=</literal> in
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Virtualization=</varname></term>
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<listitem>
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<para>Checks whether the system is executed in
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a virtualized environment and optionally test
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whether it is a specific implementation. See
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<literal>ConditionVirtualization=</literal> in
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>KernelCommandLine=</varname></term>
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<listitem>
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<para>Checks whether a specific kernel command line option
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is set (or if prefixed with the exclamation mark unset). See
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<literal>ConditionKernelCommandLine=</literal> in
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Architecture=</varname></term>
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<listitem>
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<para>Checks whether the system is running on a specific
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architecture. See <literal>ConditionArchitecture=</literal>
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in
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>[Link] Section Options</title>
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<para>The <literal>[Link]</literal> section accepts the following
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keys:</para>
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<variablelist class='network-directives'>
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<varlistentry>
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<term><varname>Description=</varname></term>
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<listitem>
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<para>A description of the device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Alias=</varname></term>
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<listitem>
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<para>The <literal>ifalias</literal> is set to this
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value.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MACAddressPolicy=</varname></term>
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<listitem>
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<para>The policy by which the MAC address should be set. The
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available policies are:
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</para>
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<variablelist>
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<varlistentry>
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<term><literal>persistent</literal></term>
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<listitem>
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<para>If the hardware has a persistent MAC address, as
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most hardware should, and if it is used by the kernel,
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nothing is done. Otherwise, a new MAC address is
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generated which is guaranteed to be the same on every
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boot for the given machine and the given device, but
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which is otherwise random. This feature depends on ID_NET_NAME_*
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properties to exist for the link. On hardware where these
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properties are not set, the generation of a persistent MAC address
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will fail.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>random</literal></term>
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<listitem>
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<para>If the kernel is using a random MAC address,
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nothing is done. Otherwise, a new address is randomly
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generated each time the device appears, typically at
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boot. Either way, the random address will have the
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<literal>unicast</literal> and
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<literal>locally administered</literal> bits set.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>none</literal></term>
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<listitem>
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<para>Keeps the MAC address assigned by the kernel.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MACAddress=</varname></term>
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<listitem>
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<para>The MAC address to use, if no
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<literal>MACAddressPolicy=</literal>
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is specified.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>NamePolicy=</varname></term>
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<listitem>
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<para>An ordered, space-separated list of policies by which
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the interface name should be set.
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<literal>NamePolicy</literal> may be disabled by specifying
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<literal>net.ifnames=0</literal> on the kernel command line.
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Each of the policies may fail, and the first successful one
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is used. The name is not set directly, but is exported to
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udev as the property <literal>ID_NET_NAME</literal>, which
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is, by default, used by a udev rule to set
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<literal>NAME</literal>. If the name has already been set by
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userspace, no renaming is performed. The available policies
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are:</para>
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<variablelist>
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<varlistentry>
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<term><literal>kernel</literal></term>
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<listitem>
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<para>If the kernel claims that the name it has set
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for a device is predictable, then no renaming is
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performed.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>database</literal></term>
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<listitem>
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<para>The name is set based on entries in the udev's
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Hardware Database with the key
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<literal>ID_NET_NAME_FROM_DATABASE</literal>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>onboard</literal></term>
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<listitem>
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<para>The name is set based on information given by
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the firmware for on-board devices, as exported by the
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udev property <literal>ID_NET_NAME_ONBOARD</literal>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>slot</literal></term>
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<listitem>
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<para>The name is set based on information given by
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the firmware for hot-plug devices, as exported by the
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udev property <literal>ID_NET_NAME_SLOT</literal>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>path</literal></term>
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<listitem>
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<para>The name is set based on the device's physical
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location, as exported by the udev property
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<literal>ID_NET_NAME_PATH</literal>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>mac</literal></term>
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<listitem>
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<para>The name is set based on the device's persistent
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MAC address, as exported by the udev property
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<literal>ID_NET_NAME_MAC</literal>.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Name=</varname></term>
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<listitem>
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<para>The interface name to use in case all the
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policies specified in
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<varname>NamePolicy=</varname> fail, or in case
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<varname>NamePolicy=</varname> is missing or
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disabled.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MTUBytes=</varname></term>
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<listitem>
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<para>The maximum transmission unit in bytes to set for the
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device. The usual suffixes K, M, G, are supported and are
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understood to the base of 1024.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>BitsPerSecond=</varname></term>
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<listitem>
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<para>The speed to set for the device, the value is rounded
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down to the nearest Mbps. The usual suffixes K, M, G, are
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supported and are understood to the base of 1000.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Duplex=</varname></term>
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<listitem>
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<para>The duplex mode to set for the device. The accepted
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values are <literal>half</literal> and
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<literal>full</literal>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>WakeOnLan=</varname></term>
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<listitem>
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<para>The Wake-on-LAN policy to set for the device. The
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supported values are:</para>
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<variablelist>
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<varlistentry>
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<term><literal>phy</literal></term>
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<listitem>
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<para>Wake on PHY activity.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>magic</literal></term>
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<listitem>
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<para>Wake on receipt of a magic packet.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>off</literal></term>
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<listitem>
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<para>Never wake.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<example>
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<title>/usr/lib/systemd/network/99-default.link</title>
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<para>The link file <filename>99-default.link</filename> that is
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shipped with systemd defines the default naming policy for
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links.</para>
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<programlisting>[Link]
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NamePolicy=kernel database onboard slot path
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MACAddressPolicy=persistent</programlisting>
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</example>
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<example>
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<title>/etc/systemd/network/10-dmz.link</title>
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<para>This example assigns the fixed name
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<literal>dmz0</literal> to the interface with the MAC address
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00:a0:de:63:7a:e6:</para>
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<programlisting>[Match]
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MACAddress=00:a0:de:63:7a:e6
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[Link]
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Name=dmz0</programlisting>
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</example>
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<example>
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<title>/etc/systemd/network/10-internet.link</title>
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<para>This example assigns the fixed name
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<literal>internet0</literal> to the interface with the device
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path <literal>pci-0000:00:1a.0-*</literal>:</para>
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<programlisting>[Match]
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Path=pci-0000:00:1a.0-*
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[Link]
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Name=internet0</programlisting>
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</example>
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<example>
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<title>/etc/systemd/network/25-wireless.link</title>
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<para>Here's an overly complex example that shows the use of a large number of [Match] and [Link] settings.</para>
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<programlisting>[Match]
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MACAddress=12:34:56:78:9a:bc
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Driver=brcmsmac
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Path=pci-0000:02:00.0-*
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Type=wlan
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Virtualization=no
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Host=my-laptop
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Architecture=x86-64
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[Link]
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Name=wireless0
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MTUBytes=1450
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BitsPerSecond=10M
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WakeOnLan=magic
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MACAddress=cb:a9:87:65:43:21</programlisting>
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</example>
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</refsect1>
|
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|
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<refsect1>
|
|
<title>See Also</title>
|
|
<para>
|
|
<citerefentry>
|
|
<refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry>,
|
|
<citerefentry>
|
|
<refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry>,
|
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<citerefentry>
|
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<refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum>
|
|
</citerefentry>,
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<citerefentry>
|
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<refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum>
|
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</citerefentry>
|
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</para>
|
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</refsect1>
|
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|
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</refentry>
|