systemd-networkd.service
systemd
Developer
Tom
Gundersen
teg@jklm.no
systemd-networkd.service
8
systemd-networkd.service
systemd-networkd
Network manager
systemd-networkd.service
/usr/lib/systemd/systemd-networkd
Description
systemd-networkd is a system
service that manages networks. It detects and configures
network devices as they appear, as well as creating virtual
network devices.
To configure low-level link settings independently of
networks, see
systemd.link5
.
Network configurations applied before networkd is started
are not removed, and static configuration applied by networkd
is 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.
Configuration Files
The configuration files are read from the files located in the
system network directory /usr/lib/systemd/network,
the volatile runtime network directory
/run/systemd/network and the local administration
network directory /etc/systemd/network.
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
/etc have the highest priority, files in
/run take precedence over files with the same
name in /usr/lib. This can be used to override a
system-supplied configuration file with a local file if needed; a symlink in
/etc with the same name as a configuration file in
/usr/lib, pointing to /dev/null,
disables the configuration file entirely.
Virtual Network Devices
Virtual Network Device files must have the extension
.netdev; other extensions are ignored. Virtual
network devices are created as soon as networkd is started.
A virtual network device is only created if the
[Match] section matches the current
environment, or if the section is empty. The following keys are accepted:
Host=
Matches against the hostname or machine ID of the
host. See ConditionHost= in
systemd.unit5
for details.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific
implementation. See ConditionVirtualization= in
systemd.unit5
for details.
KernelCommandLine=
Checks whether a specific kernel command line option is
set (or if prefixed with the exclamation mark unset). See
ConditionKernelCommandLine= in
systemd.unit5
for details.
Architecture=
Checks whether the system is running on a specific
architecture. See ConditionArchitecture= in
systemd.unit5
for details.
The [NetDev] section accepts the following
keys:
Name=
The interface name used when creating the
netdev. This option is compulsory.
Kind=
The netdev kind. Currently, bridge,
bond and vlan
are supported. This option is compulsory.
The [VLAN] section only applies for netdevs of kind vlan,
and accepts the following key:
Id=
The VLAN ID to use. An integer in the range 0–4094.
This option is compulsory.
Networks
Network files must have the extension .network;
other extensions are ignored. Networks are applied to links whenever the links
appear.
The network file contains a [Match] section,
which determines if a given network file may be applied to a given device;
and a [Network] section specifying how the device should
be configured. The first (in lexical order) of the network files that
matches a given device is applied.
A network file is said to match a device if each of the entries in the
[Match] section matches, or if the section is empty.
The following keys are accepted:
MACAddress=
The hardware address.
Path=
The persistent path, as exposed by the udev
property ID_PATH. May contain shell
style globs.
Driver=
The driver currently bound to the device, as
exposed by the udev property DRIVER
of its parent device, or if that is not set the driver
as exposed by ethtool -i of the
device itself.
Type=
The device type, as exposed by the udev property
DEVTYPE.
Name=
The device name, as exposed by the udev property
INTERFACE. May contain shell style
globs.
Host=
Matches against the hostname or machine ID of the
host. See ConditionHost= in
systemd.unit5
for details.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific
implementation. See ConditionVirtualization= in
systemd.unit5
for details.
KernelCommandLine=
Checks whether a specific kernel command line option is
set (or if prefixed with the exclamation mark unset). See
ConditionKernelCommandLine= in
systemd.unit5
for details.
Architecture=
Checks whether the system is running on a specific
architecture. See ConditionArchitecture= in
systemd.unit5
for details.
The [Network] section accepts the following keys:
Description=
A description of the device. This is only used for
presentation purposes.
DHCP=
A boolean. When true, enables basic DHCPv4 support.
Address=
A static IPv4 or IPv6 address and its prefix length,
separated by a / character. Specify this
key more than once to configure several addresses.
The format of the address must be as described in
inet_pton3
. This is a short-hand for an [Address] section only containing an Address key (see below).
Gateway=
The gateway address, which must be in the format described in
inet_pton3
. This is a short-hand for a [Route] section only containing a Gateway key.
DNS=
A DNS server address, which must be in the format described in
inet_pton3
.
Bridge=
The name of the bridge to add the link to.
Bond=
The name of the bond to add the link to.
VLAN=
The name of a VLAN to create on the link. This option
may be specified more than once.
An [Address] section accepts the following keys.
Specify several [Address] sections to configure several
addresses.
Address=
As in the [Network] section. This key is mandatory.
Broadcast=
The broadcast address, which must be in the format described in
inet_pton3
. This key only applies to IPv4 addresses. If it is not given, it is
derived from the Address key.
Label=
An address label.
The [Route] section accepts the following keys. Specify
several [Route] sections to configure several routes.
Gateway=
As in the [Network] section. This key is mandatory.
Destination=
The destination prefix of the route. Possibly followed by a slash and the
prefixlength, if ommitted a full-length host route is assumed.
The [DHCPv4] section accepts the following keys:
UseDNS=
When true (the default), the DNS servers received from the DHCP server will
be used and take precedence over any statically configured ones.
UseMTU=
When true, the interface maximum transmission unit from the DHCP server will
be used on the current link. Defaults to false.
UseHostname=
When true (the default), the hostname received from the DHCP server
will be used as the transient hostname.
CriticalConnection=
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.
See Also
systemd1,
udev7