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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<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, all later files are ignored, even if they match as

well.</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>A whitespace-separated list of shell-style globs

matching the persistent path, as exposed by the udev

property <literal>ID_PATH</literal>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>Driver=</varname></term>

<listitem>

<para>A whitespace-separated list of shell-style globs

matching 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>A whitespace-separated list of shell-style globs

matching the device type, as exposed by the udev property

<literal>DEVTYPE</literal>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>Name=</varname></term>

<listitem>

<para>A whitespace-separated list of shell-style globs

matching the device name, as exposed by the udev property

<literal>INTERFACE</literal>.</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>[Link] Section Options</title>

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

<variablelist class='network-directives'>

<varlistentry>

<term><varname>MACAddress=</varname></term>

<listitem>

<para>The hardware address.</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.</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>yes</literal>, <literal>no</literal>,

<literal>ipv4</literal>, or <literal>ipv6</literal>.</para>

<para>Please note that by default the domain name

specified through DHCP is not used for name resolution.

See option <option>UseDomains=</option> below.</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>LinkLocalAddressing=</varname></term>

<listitem>

<para>Enables link-local address autoconfiguration. Accepts

<literal>yes</literal>, <literal>no</literal>,

<literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to

<literal>ipv6</literal>.</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>IPv6Token=</varname></term>

<listitem>

<para>An IPv6 address with the top 64 bits unset. When set, indicates the

64 bits interface part of SLAAC IPv6 addresses for this link. By default

it is autogenerated.</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>LLDP=</varname></term>

<listitem>

<para>A boolean. When true, enables LLDP link receive support.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>BindCarrier=</varname></term>

<listitem>

<para>A port or a list of ports. When set, controls the

behaviour of the current interface. When all ports in the list

are in an operational down state, the current interface is brought

down. When at least one port has carrier, the current interface

is brought up.

</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 project='man-pages'><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 project='man-pages'><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 project='man-pages'><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>IPForward=</varname></term>

<listitem><para>Configures IP forwarding for the network

interface. If enabled incoming packets on the network

interface will be forwarded to other interfaces according to

the routing table. Takes either a boolean argument, or the

values <literal>ipv4</literal> or <literal>ipv6</literal>,

which only enables IP forwarding for the specified address

family, or <literal>kernel</literal>, which preserves existing sysctl settings.

This controls the

<filename>net.ipv4.conf.&lt;interface&gt;.forwarding</filename>

and

<filename>net.ipv6.conf.&lt;interface&gt;.forwarding</filename>

sysctl options of the network interface (see <ulink

url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>

for details about sysctl options). Defaults to

<literal>no</literal>.</para>

<para>Note: unless this option is turned on, or set to <literal>kernel</literal>,

no IP forwarding is done on this interface, even if this is

globally turned on in the kernel, with the

<filename>net.ipv4.ip_forward</filename> and

<filename>net.ipv4.ip_forward</filename> sysctl

options.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>IPMasquerade=</varname></term>

<listitem><para>Configures IP masquerading for the network

interface. If enabled packets forwarded from the network

interface will be appear as coming from the local host.

Takes a boolean argument. Implies

<varname>IPForward=ipv4</varname>. Defaults to

<literal>no</literal>.</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 project='man-pages'><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.</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>Source=</varname></term>

<listitem>

<para>The source 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>

<varlistentry>

<term><varname>Scope=</varname></term>

<listitem>

<para>The scope of the route. One of the values <literal>global</literal>,

<literal>link</literal> or <literal>host</literal>. Defaults to

<literal>global</literal>.</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>

<para>This corresponds to the <option>nameserver</option>

option in <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>UseNTP=</varname></term>

<listitem>

<para>When true (the default), the NTP servers received

from the DHCP server will be used by systemd-timesyncd

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. When a name cannot be resolved

as specified, the domain name will be used a suffix and

name resolution of that will be attempted.</para>

<para>This corresponds to the <option>domain</option>

option in <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>

and should not be enabled on untrusted networks.</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>ClientIdentifier=</varname></term>

<listitem>

<para>DHCP client identifier to use. Either <literal>mac</literal>

to use the MAC address of the link or <literal>duid</literal>

(the default) to use a RFC4361-compliant Client ID.</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>[Bridge] Section Options</title>

<para>The <literal>[Bridge]</literal> section accepts the

following keys.</para>

<variablelist class='network-directives'>

<varlistentry>

<term><varname>Cost=</varname></term>

<listitem>

<para>Each port in a bridge may have different speed. Cost

is used to decide which link to use. Faster interfaces

should have lower costs</para>

</listitem>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>[BridgeFDB] Section Options</title>

<para>The <literal>[BridgeFDB]</literal> section manages the

forwarding database table of a port and accepts the following

keys. Specify several <literal>[BridgeFDB]</literal> sections to

configure several static MAC table entries.</para>

<variablelist class='network-directives'>

<varlistentry>

<term><varname>MACAddress=</varname></term>

<listitem>

<para>As in the <literal>[Network]</literal> section. This

key is mandatory.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><varname>VLANId=</varname></term>

<listitem>

<para>The VLAN Id for the new static MAC table entry. If

omitted, no VLAN Id info is appended to the new static MAC

table entry.</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=yes</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.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>