SYSTEMD.LINK(5)systemd.linkSYSTEMD.LINK(5)NAMEsystemd.link - Network device configuration
SYNOPSIS
link.link
DESCRIPTION
Network link configuration is performed by the net_setup_link udev
builtin.
The link 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. Link files must have the extension
.link; other extensions are ignored. All link files are collectively
sorted and processed in lexical order, regardless of the directories in
which they live. However, files with identical filenames replace each
other. Files in /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 link file with a local file if needed; a
symlink in /etc with the same name as a link file in /usr/lib, pointing
to /dev/null, disables the link file entirely.
The link file contains a "[Match]" section, which determines if a given
link file may be applied to a given device; and a "[Link]" section
specifying how the device should be configured. The first (in lexical
order) of the link files that matches a given device is applied.
A link 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".
Host=
Matches against the hostname or machine ID of the host. See
"ConditionHost=" in systemd.unit(5) 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.unit(5) 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.unit(5) for details.
Architecture=
Checks whether the system is running on a specific architecture.
See "ConditionArchitecture=" in systemd.unit(5) for details.
The "[Link]" section accepts the following keys:
Description=
A description of the device.
Alias=
The "ifalias" is set to this value.
MACAddressPolicy=
The policy by which the MAC address should be set. The available
policies are:
"persistent"
If the hardware has a persistent MAC address, as most hardware
should, and this is used by the kernel, nothing is done.
Otherwise, a new MAC address is generated which is guaranteed
to be the same on every boot for the given machine and the
given device, but which is otherwise random.
"random"
If the kernel is using a random MAC address, nothing is done.
Otherwise, a new address is randomly generated each time the
device appears, typically at boot.
MACAddress=
The MAC address to use, if no "MACAddressPolicy=" is specified.
NamePolicy=
An ordered, space-separated list of policies by which the interface
name should be set. "NamePolicy" may be disabled by specifying
"net.ifnames=0" on the kernel commandline. Each of the policies may
fail, and the first successful one is used. The name is not set
directly, but is exported to udev as the property "ID_NET_NAME",
which is, by default, used by a udev rule to set "NAME". The
available policies are:
"database"
The name is set based on entries in the udev's Hardware
Database with the key "ID_NET_NAME_FROM_DATABASE" .
"onboard"
The name is set based on information given by the firmware for
on-board devices, as exported by the udev property
"ID_NET_NAME_ONBOARD" .
"slot"
The name is set based on information given by the firmware for
hot-plug devices, as exported by the udev property
"ID_NET_NAME_SLOT" .
"path"
The name is set based on the device's physical location, as
exported by the udev property "ID_NET_NAME_PATH".
"mac"
The name is set based on the device's persistent MAC address,
as exported by the udev property "ID_NET_NAME_MAC".
Name=
The interface name to use in case all the policies specified in
NamePolicy= fail, or in case NamePolicy= is missing or disabled.
MTUBytes=
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.
BitsPerSecond=
The speed to set for the device, the value is rounded down to the
nearest Mbps. The usual suffixes K, M, G, are supported and are
understood to the base of 1000.
Duplex=
The duplex mode to set for the device. The accepted values are
"half" and "full".
WakeOnLan=
The Wake-on-LAN policy to set for the device. The supported values
are:
"phy"
Wake on PHY activity.
"magic"
Wake on receipt of a magic packet
"off"
Never wake.
EXAMPLE
Example 1. /etc/systemd/network/wireless.link
[Match]
MACAddress=12:34:56:78:9a:bc
Driver=brcmsmac
Path=pci-0000:02:00.0-*
Type=wlan
Virtualization=no
Host=my-laptop
Architecture=x86-64
[Link]
Name=wireless0
MTUBytes=1450
BitsPerSecond=10M
WakeOnLan=magic
MACAddress=cb:a9:87:65:43:21
SEE ALSOsystemd-udevd.service(8), udevadm(8)systemd 212SYSTEMD.LINK(5)
