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<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.</para>

<para>Network devices are managed by networkd only if they

have the udev tag <literal>systemd-networkd</literal>.</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>Network Configuration</title>

<para>The network 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 link 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>/lib</filename>. This can be used to override a

system-supplied network file with a local file if needed; a symlink in

<filename>/etc</filename> with the same name as a network file in

<filename>/lib</filename>, pointing to <filename>/dev/null</filename>,

disables the network file entirely. Network files must have the extension

<filename>.network</filename>; other extensions are ignored.</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>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>

.</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>

.</para>

</listitem>

</varlistentry>

</variablelist>

</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>