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<refentry id="systemd.netdev" 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.netdev</refentrytitle>
                <manvolnum>5</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>systemd.netdev</refname>
                <refpurpose>Virtual Network Device configuration</refpurpose>
        </refnamediv>

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

        <refsect1>
                <title>Description</title>

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

                <para>Virtual Network Device files must have the extension
                <filename>.netdev</filename>; other extensions are ignored. Virtual
                network devices are created as soon as networkd is started. If a netdev
                with the specified name already exists, networkd will use that as-is
                rather than create its own. Note that the settings of the pre-existing
                netdev will not be changed by networkd.</para>

                <para>The <filename>.netdev</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>A virtual network device is only created if the
                <literal>[Match]</literal> section matches the current
                environment, or if the section is empty. The following keys are accepted:</para>

                        <variablelist class='network-directives'>
                                <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>[NetDev] Section Options</title>

                        <para>The <literal>[NetDev]</literal> section accepts the following
                        keys:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Description=</varname></term>
                                        <listitem>
                                                <para>A free-form description of the netdev.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Name=</varname></term>
                                        <listitem>
                                                <para>The interface name used when creating the
                                                netdev. This option is compulsory.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Kind=</varname></term>
                                        <listitem>
                                                <para>The netdev kind. Currently, <literal>bridge</literal>,
                                                <literal>bond</literal>, <literal>vlan</literal>,
                                                <literal>macvlan</literal>, <literal>vxlan</literal>,
                                                <literal>ipip</literal>, <literal>gre</literal>,
                                                <literal>sit</literal>, <literal>vti</literal>,
                                                <literal>veth</literal>, <literal>tun</literal>,
                                                <literal>tap</literal> and <literal>dummy</literal>
                                                are supported. This option is compulsory.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MTUBytes=</varname></term>
                                        <listitem>
                                                <para>The maximum transmission unit in bytes to
                                                set for the device. The usual suffixes K, M, G,
                                                are supported and are understood to the base of
                                                1024. This key is not currently suported for
                                                <literal>tun</literal> or <literal>tap</literal> devices.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MACAddress=</varname></term>
                                        <listitem>
                                                <para>The MAC address to use for the device.
                                                If none is given, one is generated based on
                                                the interface name and the
                                                <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
                                                This key is not currently suported for <literal>tun</literal> or <literal>tap</literal> devices.
                                                </para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>

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

                        <para>The <literal>[VLAN]</literal> section only applies for netdevs of kind <literal>vlan</literal>,
                        and accepts the following key:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Id=</varname></term>
                                        <listitem>
                                                <para>The VLAN ID to use. An integer in the range 0–4094.
                                                This option is compulsory.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>

        </refsect1>

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

                        <para>The <literal>[MACVLAN]</literal> section only applies for netdevs of kind
                        <literal>macvlan</literal>, and accepts the following key:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Mode=</varname></term>
                                        <listitem>
                                                <para>The MACVLAN mode to use. The supported options are
                                                <literal>private</literal>, <literal>vepa</literal>,
                                                <literal>bridge</literal> and <literal>passthru</literal>.
                                                </para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>

        </refsect1>
        <refsect1>
                <title>[VXLAN] Section Options</title>
                        <para>The <literal>[VXLAN]</literal> section only applies for netdevs of kind
                        <literal>vxlan</literal>, and accepts the following key:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Id=</varname></term>
                                        <listitem>
                                                <para>The VXLAN ID to use.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Group=</varname></term>
                                        <listitem>
                                                <para>An assigned multicast group IP address.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>TOS=</varname></term>
                                        <listitem>
                                                <para>The Type Of Service byte value for a vxlan interface.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>TTL=</varname></term>
                                        <listitem>
                                                <para>A fixed Time To Live N on Virtual eXtensible Local Area Network packets.
                                                N is a number in the range 1-255. 0 is a special value meaning that packets
                                                inherit the TTL value.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MacLearning=</varname></term>
                                        <listitem>
                                                <para>A boolean. When true, enables dynamic MAC learning
                                                to discover remote MAC addresses.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>
        <refsect1>
                <title>[Tunnel] Section Options</title>

                        <para>The <literal>[Tunnel]</literal> section only applies for netdevs of kind
                        <literal>ipip</literal>, <literal>sit</literal>, <literal>gre</literal> and
                        <literal>vti</literal> and accepts the following keys:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Local=</varname></term>
                                        <listitem>
                                                <para>A static local address for tunneled packets.
                                                It must be an address on another interface of this host.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Remote=</varname></term>
                                        <listitem>
                                                <para>The remote endpoint of the tunnel.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>TOS=</varname></term>
                                        <listitem>
                                                <para>The Type Of Service byte value for a tunnel interface.
                                                For details about the TOS see the
                                                <ulink url="http://tools.ietf.org/html/rfc1349">
                                                Type of Service in the Internet Protocol Suite
                                                </ulink> document.
                                                </para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>TTL=</varname></term>
                                        <listitem>
                                                <para>A fixed Time To Live N on tunneled packets.
                                                N is a number in the range 1-255. 0 is a special value meaning that packets
                                                inherit the TTL value. The default value for IPv4 tunnels is: inherit.
                                                The default value for IPv6 tunnels is: 64.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>DiscoverPathMTU=</varname></term>
                                        <listitem>
                                                <para>A boolean. When true, enables Path MTU Discovery on the tunnel.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>
        <refsect1>
                <title>[Peer] Section Options</title>

                        <para>The <literal>[Peer]</literal> section only applies for netdevs of kind <literal>veth</literal>
                        and accepts the following key:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Name=</varname></term>
                                        <listitem>
                                                <para>The interface name used when creating the netdev.
                                                This option is compulsory.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MACAddress=</varname></term>
                                        <listitem>
                                                <para>The peer MACAddress, if not set it is generated in the same
                                                way as the MAC address of the main interface.</para>
                                        </listitem>
                                </varlistentry>
                        </variablelist>
        </refsect1>
        <refsect1>
                <title>[Tun] Section Options</title>

                        <para>The <literal>[Tun]</literal> section only applies for netdevs of kind
                        <literal>tun</literal>, and accepts the following keys:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>OneQueue=</varname></term>
                                        <listitem><para>Takes a boolean argument. Configures whether
                                        all packets are queued at the device (enabled), or a fixed number
                                        of packets are queued at the device and the rest at the
                                        <literal>qdisc</literal>. Defaults to <literal>no</literal>.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>MultiQueue=</varname></term>
                                        <listitem><para>Takes a boolean argument. Configures whether to
                                        use multiple file descriptors (queues) to parallelize packets
                                        sending and receiving. Defaults to <literal>no</literal>.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>PacketInfo=</varname></term>
                                        <listitem><para>Takes a boolean argument. Configures whether packets
                                        should be prepened with four extra bytes (two flag bytes and two
                                        protocol bytes). If disabled it indicates that the packets will be
                                        pure IP packets. Defaults to <literal>no</literal>.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>User=</varname></term>
                                        <listitem><para>User to grant access to the <filename>/dev/net/tun</filename>
                                        device.</para>
                                        </listitem>
                                </varlistentry>
                                <varlistentry>
                                        <term><varname>Group=</varname></term>
                                        <listitem><para>Group to grant access to the <filename>/dev/net/tun</filename>
                                        device.</para>
                                        </listitem>
                                </varlistentry>

                        </variablelist>

        </refsect1>

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

                        <para>The <literal>[Tap]</literal> section only applies for netdevs of kind
                        <literal>tap</literal>, and accepts the same keys as the
                        <literal>[Tun]</literal> section.</para>
        </refsect1>

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

                        <para>The <literal>[Bond]</literal> section accepts the following
                        key:</para>

                        <variablelist class='network-directives'>
                                <varlistentry>
                                        <term><varname>Mode=</varname></term>
                                        <listitem>
                                          <para>Specifies one of the bonding policies. The default is
                                          <literal>balance-rr</literal> (round robin). Possible values are
                                                <literal>balance-rr</literal>,
                                                <literal>active-backup</literal>,
                                                <literal>balance-xor</literal>,
                                                <literal>broadcast</literal>,
                                                <literal>802.3ad</literal>,
                                                <literal>balance-tlb</literal>, and
                                                <literal>balance-alb</literal>.
                                          </para>
                                        </listitem>
                                </varlistentry>

                                <varlistentry>
                                  <term><varname>TransmitHashPolicy=</varname></term>
                                  <listitem>
                                    <para>Selects the transmit hash policy to use for slave selection in
                                    balance-xor, 802.3ad, and tlb modes. Possible values are
                                    <literal>layer2</literal>,
                                    <literal>layer3+4</literal>,
                                    <literal>layer2+3</literal>,
                                    <literal>encap2+3</literal>,
                                    <literal>802.3ad</literal>, and
                                    <literal>encap3+4</literal>.
                                    </para>
                                  </listitem>
                                </varlistentry>

                                <varlistentry>
                                  <term><varname>LACPTransmitRate=</varname></term>
                                  <listitem>
                                    <para>Specifies the rate with which link partner
                                    transmits Link Aggregation Control Protocol Data Unit packets
                                    in 802.3ad mode. Possible values are
                                    <literal>slow</literal>, which requests partner to transmit LACPDUs every 30 seconds, and
                                    <literal>fast</literal>, which requests partner to transmit LACPDUs every second.
                                    The default value is <literal>slow</literal>.</para>
                                  </listitem>
                                </varlistentry>

                                <varlistentry>
                                  <term><varname>MIIMonitorSec=</varname></term>
                                  <listitem>
                                    <para>Specifies the frequency that Media Independent Interface link
                                    monitoring will occur. A value of zero disables MII link monitoring.
                                    This values is rounded down to the nearest millisecond. The default
                                    value is 0.</para>
                                  </listitem>
                                </varlistentry>

                                <varlistentry>
                                  <term><varname>UpDelaySec=</varname></term>
                                  <listitem>
                                    <para>Specifies the delay before a link is enabled after a link up
                                    status has been detected. This value is rounded down to a multiple of
                                    MIIMonitorSec. The default value is 0.</para>
                                  </listitem>
                                </varlistentry>

                                <varlistentry>
                                  <term><varname>DownDelaySec=</varname></term>
                                  <listitem>
                                    <para>Specifies the delay before a link is disabled after a link down
                                    status has been detected. This value is rounded down to a multiple of
                                    MIIMonitorSec. The default value is 0.</para>
                                  </listitem>
                                </varlistentry>

                        </variablelist>
        </refsect1>

        <refsect1>
                <title>Example</title>
                <example>
                        <title>/etc/systemd/network/bridge.netdev</title>

                        <programlisting>[NetDev]
Name=bridge0
Kind=bridge</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/vlan1.netdev</title>

                        <programlisting>[Match]
Virtualization=no

[NetDev]
Name=vlan1
Kind=vlan

[VLAN]
Id=1</programlisting>
                </example>
                <example>
                        <title>/etc/systemd/network/ipip.netdev</title>
                        <programlisting>[NetDev]
Name=ipip-tun
Kind=ipip
MTUBytes=1480

[Tunnel]
Local=192.168.223.238
Remote=192.169.224.239
TTL=64</programlisting>
                </example>
                <example>
                  <title>/etc/systemd/network/tap.netdev</title>
                  <programlisting>[NetDev]
Name=tap-test
Kind=tap

[Tap]
MultiQueue=true
PacketInfo=true</programlisting> </example>

                <example>
                        <title>/etc/systemd/network/sit.netdev</title>
                        <programlisting>[NetDev]
Name=sit-tun
Kind=sit
MTUBytes=1480

[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/gre.netdev</title>
                        <programlisting>[NetDev]
Name=gre-tun
Kind=gre
MTUBytes=1480

[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239</programlisting>
                </example>

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

                        <programlisting>[NetDev]
Name=vti-tun
Kind=vti
MTUBytes=1480

[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/veth.netdev</title>
                        <programlisting>[NetDev]
Name=veth-test
Kind=veth

[Peer]
Name=veth-peer</programlisting>
                </example>

                <example>
                        <title>/etc/systemd/network/dummy.netdev</title>
                        <programlisting>[NetDev]
Name=dummy-test
Kind=dummy
MACAddress=12:34:56:78:9a:bc</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.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
