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<refentry id="systemd.network" conditional='ENABLE_NETWORKD'>

        <refentryinfo>
                <title>systemd.network</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.network</refentrytitle>
                <manvolnum>5</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>systemd.network</refname>
                <refpurpose>Network configuration</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <para><filename><replaceable>network</replaceable>.network</filename></para>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

		<para>Network setup is performed by
		<citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
		</para>

                <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 <filename>.network</filename> 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>

        </refsect1>

        <refsect1>
                <title>[Match] Section Options</title>

                        <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>. May contain shell
                                                style globs.</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>
                                                of its parent device, or if that is not set the driver
                                                as exposed by <literal>ethtool -i</literal> of the
                                                device itself.</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>. May contain shell style
                                                globs.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Host=</varname></term>
                                        <listitem>
                                                <para>Matches against the hostname or machine ID of the
                                                host. See <literal>ConditionHost=</literal> in
                                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                                                for details.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Virtualization=</varname></term>
                                        <listitem>
                                                <para>Checks whether the system is executed in a virtualized
                                                environment and optionally test whether it is a specific
                                                implementation. See <literal>ConditionVirtualization=</literal> in
                                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                                                for details.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>KernelCommandLine=</varname></term>
                                        <listitem>
                                                <para>Checks whether a specific kernel command line option is
                                                set (or if prefixed with the exclamation mark unset). See
                                                <literal>ConditionKernelCommandLine=</literal> in
                                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                                                for details.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Architecture=</varname></term>
                                        <listitem>
                                                <para>Checks whether the system is running on a specific
                                                architecture. See <literal>ConditionArchitecture=</literal> in
                                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                                                for details.
                                                </para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>

        </refsect1>

        <refsect1>
                <title>[Network] Section Options</title>

                        <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>Enables DHCPv4 and/or DHCPv6 support. Accepts
                                                <literal>both</literal>, <literal>none</literal>,
                                                <literal>v4</literal> or <literal>v6</literal>.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>DHCPServer=</varname></term>
                                        <listitem>
                                                <para>A boolean. Enables a basic DHCPv4 server on the
                                                device. Mostly useful for handing out leases to container
                                                instances.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>IPv4LL=</varname></term>
                                        <listitem>
                                                <para>A boolean. When true, enables IPv4 link-local support.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>IPv4LLRoute=</varname></term>
                                        <listitem>
                                                <para>A boolean. When true, sets up the route needed for
                                                non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
                                                to false.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>LLMNR=</varname></term>
                                        <listitem>
                                                <para>A boolean or <literal>resolve</literal>. When true, enables
                                                Link-Local Multicast Name Resolution on the link, when set to
                                                <literal>resolve</literal> only resolution is enabled, but not
                                                announcement. Defaults to true.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Address=</varname></term>
                                        <listitem>
                                                <para>A static IPv4 or IPv6 address and its prefix length,
                                                separated by a <literal>/</literal> character. Specify this
                                                key more than once to configure several addresses.
                                                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). This option may be specified
                                                more than once.
                                                </para>

                                                <para>If the specified
                                                address is 0.0.0.0
                                                (for IPv4) or [::]
                                                (for IPv6), a new
                                                address range of the
                                                requested size is
                                                automatically
                                                allocated from a
                                                system-wide pool of
                                                unused ranges. The
                                                allocated range is
                                                checked against all
                                                current network
                                                interfaces and all
                                                known network
                                                configuration files to
                                                avoid address range
                                                conflicts. The default
                                                system-wide pool
                                                consists of
                                                192.168.0.0/16,
                                                172.16.0.0/12 and
                                                10.0.0.0/8 for IPv4,
                                                and fc00::/7 for
                                                IPv6. This
                                                functionality is
                                                useful to manage a
                                                large number of
                                                dynamically created
                                                network interfaces
                                                with the same network
                                                configuration and
                                                automatic address
                                                range
                                                assignment.</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. This option may be specified more than once.</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>.
                                                This option may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Domains=</varname></term>
                                        <listitem>
                                                <para>The domains used for DNS resolution over this link.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>NTP=</varname></term>
                                        <listitem>
                                                <para>An NTP server address. This option may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Bridge=</varname></term>
                                        <listitem>
                                                <para>The name of the bridge to add the link to.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Bond=</varname></term>
                                        <listitem>
                                                <para>The name of the bond to add the link to.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>VLAN=</varname></term>
                                        <listitem>
                                                <para>The name of a VLAN to create on the link. This option
                                                may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MACVLAN=</varname></term>
                                        <listitem>
                                                <para>The name of a MACVLAN to create on the link. This option
                                                may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>VXLAN=</varname></term>
                                        <listitem>
                                                <para>The name of a VXLAN to create on the link. This option
                                                may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Tunnel=</varname></term>
                                        <listitem>
                                                <para>The name of a Tunnel to create on the link. This option
                                                may be specified more than once.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>

        </refsect1>

        <refsect1>
                <title>[Address] Section Options</title>

                        <para>An <literal>[Address]</literal> section accepts the following keys.
                        Specify several <literal>[Address]</literal> sections to configure several
                        addresses.</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>Peer=</varname></term>
                                        <listitem>
                                                <para>The peer address in a point-to-point connection. Accepts the same format as
                                                the <literal>Address</literal> key.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Broadcast=</varname></term>
                                        <listitem>
                                                <para>The broadcast address, which must be in the format described in
                                                <citerefentry><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
                                                This key only applies to IPv4 addresses. If it is not given, it is
                                                derived from the <literal>Address</literal> key.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Label=</varname></term>
                                        <listitem>
                                                <para>An address label.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>

        <refsect1>
                <title>[Route] Section Options</title>
                        <para>The <literal>[Route]</literal> section accepts the following keys. Specify
                        several <literal>[Route]</literal> sections to configure several routes.</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 omitted, a full-length host route is assumed.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Metric=</varname></term>
                                        <listitem>
                                                <para>The metric of the route. An unsigned integer</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>

        <refsect1>
                <title>[DHCP] Section Options</title>
                        <para>The <literal>[DHCP]</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>SendHostname=</varname></term>
                                        <listitem>
                                                <para>When true (the default), the machine's hostname will be sent to the DHCP
                                                server</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>
                                <varlistentry>
                                        <term><varname>UseDomains=</varname></term>
                                        <listitem>
                                                <para>When true (not the default), the domain name received from the DHCP server
                                                will be used for DNS resolution over this link.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>UseRoutes=</varname></term>
                                        <listitem>
                                                <para>When true (the default), the static routes will be requested from the DHCP server
                                                and added to the routing table with metric of 1024.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>CriticalConnection=</varname></term>
                                        <listitem>
                                                <para>When true, the connection will never be torn down even if the DHCP lease
                                                expires. This is contrary to the DHCP specification, but may be the best choice
                                                if, say, the root filesystem relies on this connection. Defaults to false.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>VendorClassIdentifier=</varname></term>
                                        <listitem>
                                                <para>The vendor class identifier used to identify vendor type and configuration.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>RequestBroadcast=</varname></term>
                                        <listitem>
                                                <para>Request the server to use broadcast messages before the IP address has been
                                                configured. This is necessary for devices that cannot receive RAW packets, or that
                                                cannot receive packets at all before an IP address has been configured. On the other
                                                hand, this must not be enabled on networks where broadcasts are filtered out.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>RouteMetric=</varname></term>
                                        <listitem>
                                                <para>Set the routing metric for routes specified by the DHCP server.</para>
                                        </listitem>
                                </varlistentry>
                       </variablelist>

        </refsect1>

        <refsect1>
                <title>Example</title>
                <example>
                        <title>/etc/systemd/network/50-static.network</title>

                        <programlisting>[Match]
Name=enp2s0

[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/80-dhcp.network</title>

                        <programlisting>[Match]
Name=en*

[Network]
DHCP=both</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/bridge-static.network</title>

                        <programlisting>[Match]
Name=bridge0

[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/bridge-slave-interface.network</title>

                        <programlisting>[Match]
Name=enp2s0

[Network]
Bridge=bridge0</programlisting>
                </example>
                <example>
                        <title>/etc/systemd/network/ipip.network</title>

                        <programlisting>[Match]
Name=em1

[Network]
Tunnel=ipip-tun</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/sit.network</title>

                        <programlisting>[Match]
Name=em1

[Network]
Tunnel=sit-tun</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/gre.network</title>

                        <programlisting>[Match]
Name=em1

[Network]
Tunnel=gre-tun</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/vti.network</title>

                        <programlisting>[Match]
Name=em1

[Network]
Tunnel=vti-tun</programlisting>
                </example>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
