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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2013 Tom Gundersen
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd-networkd.service" conditional='ENABLE_NETWORKD'>
<refentryinfo>
<title>systemd-networkd.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Tom</firstname>
<surname>Gundersen</surname>
<email>teg@jklm.no</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-networkd.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-networkd.service</refname>
<refname>systemd-networkd</refname>
<refpurpose>Network manager</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-networkd.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-networkd</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-networkd</command> is a system
service that manages networks. It detects and configures
network devices as they appear, as well as creating virtual
network devices.</para>
<para>Network configurations applied before networkd is started
are not removed, and configuration applied by networkd are not
removed when networkd exits. This ensures restarting networkd
does not cut the network connection, and, in particular, that
it is safe to transition between the initrd and the real root,
and back.</para>
</refsect1>
<refsect1><title>Configuration Files</title>
<para>The configuration files are read from the files located in the
system network directory <filename>/usr/lib/systemd/network</filename>,
the volatile runtime network directory
<filename>/run/systemd/network</filename> and the local administration
network directory <filename>/etc/systemd/network</filename>.
All configuration files are collectively sorted and processed in lexical order,
regardless of the directories in which they live. However, files with
identical filenames replace each other. Files in
<filename>/etc</filename> have the highest priority, files in
<filename>/run</filename> take precedence over files with the same
name in <filename>/usr/lib</filename>. This can be used to override a
system-supplied configuration file with a local file if needed; a symlink in
<filename>/etc</filename> with the same name as a configuration file in
<filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
disables the configuration file entirely.</para>
<refsect2><title>Virtual Network Devices</title>
<para>Netdev files must have the extension <filename>.netdev</filename>;
other extensions are ignored. Virtual network devices are created as soon
as networkd is started.</para>
<para>The <literal>[Netdev]</literal> section accepts the following
keys:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>Name</varname></term>
<listitem>
<para>The interface name used when creating the
bridge. This option is compulsory.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Kind</varname></term>
<listitem>
<para>The netdev kind. Currently, 'bridge' and 'bond' are
supported. This option is compulsory.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2><title>Networks</title>
<para>Network files must have the extension <filename>.network</filename>;
other extensions are ignored. Networks are applied to links whenever the links
appear.</para>
<para>The network file contains a <literal>[Match]</literal> section,
which determines if a given network file may be applied to a given device;
and a <literal>[Network]</literal> section specifying how the device should
be configured. The first (in lexical order) of the network files that
matches a given device is applied.</para>
<para>A network file is said to match a device if each of the entries in the
<literal>[Match]</literal> section matches, or if the section is empty.
The following keys are accepted:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>MACAddress</varname></term>
<listitem>
<para>The hardware address.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Path</varname></term>
<listitem>
<para>The persistent path, as exposed by the udev
property <literal>ID_PATH</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Driver</varname></term>
<listitem>
<para>The driver currently bound to the device, as
exposed by the udev property <literal>DRIVER</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Type</varname></term>
<listitem>
<para>The device type, as exposed by the udev property
<literal>DEVTYPE</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Name</varname></term>
<listitem>
<para>The device name, as exposed by the udev property
<literal>INTERFACE</literal>.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The <literal>[Network]</literal> section accepts the following keys:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>Description</varname></term>
<listitem>
<para>A description of the device. This is only used for
presentation purposes.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>DHCP</varname></term>
<listitem>
<para>A boolean. When true enables basic DHCPv4 support.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Address</varname></term>
<listitem>
<para>A static IPv4 or IPv6 address and its prefix length,
separated by a '/' character. The format of the address must
be as described in
<citerefentry><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>
. This is a short-hand for an [Address] section only containing an Address key (see below).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Gateway</varname></term>
<listitem>
<para>The gateway address, which must be in the format described in
<citerefentry><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>
. This is a short-hand for a [Route] section only containing a Gateway key.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>DNS</varname></term>
<listitem>
<para>A DNS server address, which must be in the format described in
<citerefentry><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>
.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Bridge</varname></term>
<listitem>
<para>The name of the bridge to add the configured link to.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Bond</varname></term>
<listitem>
<para>The name of the bond to add the configured link to.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The <literal>[Address]</literal> section accepts the following keys:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>Address</varname></term>
<listitem>
<para>As in the <literal>[Network]</literal> section. This key is mandatory.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Label</varname></term>
<listitem>
<para>An address label.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The <literal>[Route]</literal> section accepts the following keys:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>Gateway</varname></term>
<listitem>
<para>As in the <literal>[Network]</literal> section. This key is mandatory.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>Destination</varname></term>
<listitem>
<para>The destination prefix of the route. Possibly followed by a slash and the
prefixlength, if ommitted a full-length host route is assumed.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The <literal>[DHCPv4]</literal> section accepts the following keys:</para>
<variablelist class='network-directives'>
<varlistentry>
<term><varname>UseDNS</varname></term>
<listitem>
<para>When true (the default) the DNS servers received from the DHCP server will
be used, and take precedence over any statically configured ones.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>UseMTU</varname></term>
<listitem>
<para>When true the interface maximum transmission unit from the DHCP server will
be used on the current link. Defaults to false.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>UseHostname</varname></term>
<listitem>
<para>When true (the default) the hostname received from the DHCP server
will be used as the transient hostname.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
</para>
</refsect1>
</refentry>
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