[MATCH] SECTION OPTIONS¶
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=
A whitespace-separated list of hardware addresses. Use
full colon-, hyphen- or dot-delimited hexadecimal. See the example below. This
option may appear more than once, in which case the lists are merged. If the
empty string is assigned to this option, the list of hardware addresses
defined prior to this is reset.
Example:
MACAddress=01:23:45:67:89:ab 00-11-22-33-44-55 AABB.CCDD.EEFF
OriginalName=
A whitespace-separated list of shell-style globs matching
the device name, as exposed by the udev property "INTERFACE". This
cannot be used to match on names that have already been changed from
userspace. Caution is advised when matching on kernel-assigned names, as they
are known to be unstable between reboots.
Path=
A whitespace-separated list of shell-style globs matching
the persistent path, as exposed by the udev property
"ID_PATH".
Driver=
A whitespace-separated list of shell-style globs matching
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=
A whitespace-separated list of shell-style globs matching
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.
KernelVersion=
Checks whether the kernel version (as reported by
uname -r) matches a certain expression (or if prefixed with the
exclamation mark does not match it). See "ConditionKernelVersion="
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.
[LINK] SECTION OPTIONS¶
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 if it 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. This feature depends on ID_NET_NAME_* properties to exist for the
link. On hardware where these properties are not set, the generation of a
persistent MAC address will fail.
"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. Either way, the random address will have the
"unicast" and "locally administered" bits set.
"none"
Keeps the MAC address assigned by the kernel.
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 command line. 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". If the name
has already been set by userspace, no renaming is performed. The available
policies are:
"kernel"
If the kernel claims that the name it has set for a
device is predictable, then no renaming is performed.
"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". See
systemd.net-naming-scheme(7).
"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". See
systemd.net-naming-scheme(7).
"path"
The name is set based on the device's physical location,
as exported by the udev property "ID_NET_NAME_PATH". See
systemd.net-naming-scheme(7).
"mac"
The name is set based on the device's persistent MAC
address, as exported by the udev property "ID_NET_NAME_MAC". See
systemd.net-naming-scheme(7).
Name=
The interface name to use in case all the policies
specified in
NamePolicy= fail, or in case
NamePolicy= is missing
or disabled.
Note that specifying a name that the kernel might use for another
interface (for example "eth0") is dangerous because the name
assignment done by udev will race with the assignment done by the kernel,
and only one interface may use the name. Depending on the order of
operations, either udev or the kernel will win, making the naming
unpredictable. It is best to use some different prefix, for example
"internal0"/"external0" or
"lan0"/"lan1"/"lan3".
AlternativeNamesPolicy=
A space-separated list of policies by which the
interface's alternative names should be set. Each of the policies may fail,
and all successful policies are used. The available policies are
"database", "onboard", "slot", "path",
and "mac". If the kernel does not support the alternative names,
then this setting will be ignored.
AlternativeName=
The alternative interface name to use. This option can be
specified multiple times. If the empty string is assigned to this option, the
list is reset, and all prior assignments have no effect. If the kernel does
not support the alternative names, then this setting will be ignored.
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".
AutoNegotiation=
Enables or disables automatic negotiation of transmission
parameters. Autonegotiation is a procedure by which two connected ethernet
devices choose common transmission parameters, such as speed, duplex mode, and
flow control. Takes a boolean value. Unset by default, which means that the
kernel default will be used.
Note that if autonegotiation is enabled, speed and duplex settings
are read-only. If autonegotation is disabled, speed and duplex settings are
writable if the driver supports multiple link modes.
WakeOnLan=
The Wake-on-LAN policy to set for the device. The
supported values are:
"phy"
Wake on PHY activity.
"unicast"
Wake on unicast messages.
"multicast"
Wake on multicast messages.
"broadcast"
Wake on broadcast messages.
"arp"
Wake on ARP.
"magic"
Wake on receipt of a magic packet.
"secureon"
Enable secureon(tm) password for MagicPacket(tm).
"off"
Never wake.
Defaults to "off".
Port=
The port option is used to select the device port. The
supported values are:
"tp"
An Ethernet interface using Twisted-Pair cable as the
medium.
"aui"
Attachment Unit Interface (AUI). Normally used with
hubs.
"bnc"
An Ethernet interface using BNC connectors and co-axial
cable.
"mii"
An Ethernet interface using a Media Independent Interface
(MII).
"fibre"
An Ethernet interface using Optical Fibre as the
medium.
TCPSegmentationOffload=
The TCP Segmentation Offload (TSO) when true enables TCP
segmentation offload. Takes a boolean value. Defaults to
"unset".
TCP6SegmentationOffload=
The TCP6 Segmentation Offload (tx-tcp6-segmentation) when
true enables TCP6 segmentation offload. Takes a boolean value. Defaults to
"unset".
GenericSegmentationOffload=
The Generic Segmentation Offload (GSO) when true enables
generic segmentation offload. Takes a boolean value. Defaults to
"unset".
GenericReceiveOffload=
The Generic Receive Offload (GRO) when true enables
generic receive offload. Takes a boolean value. Defaults to
"unset".
LargeReceiveOffload=
The Large Receive Offload (LRO) when true enables large
receive offload. Takes a boolean value. Defaults to "unset".
RxChannels=
Sets the number of receive channels (a number between 1
and 4294967295) .
TxChannels=
Sets the number of transmit channels (a number between 1
and 4294967295).
OtherChannels=
Sets the number of other channels (a number between 1 and
4294967295).
CombinedChannels=
Sets the number of combined set channels (a number
between 1 and 4294967295).
EXAMPLES¶
Example 1. /usr/lib/systemd/network/99-default.link
The link file 99-default.link that is shipped with systemd defines
the default naming policy for links.
[Link]
NamePolicy=kernel database onboard slot path
MACAddressPolicy=persistent
Example 2. /etc/systemd/network/10-dmz.link
This example assigns the fixed name "dmz0" to the
interface with the MAC address 00:a0:de:63:7a:e6:
[Match]
MACAddress=00:a0:de:63:7a:e6
[Link]
Name=dmz0
Example 3. /etc/systemd/network/10-internet.link
This example assigns the fixed name "internet0" to the
interface with the device path "pci-0000:00:1a.0-*":
[Match]
Path=pci-0000:00:1a.0-*
[Link]
Name=internet0
Example 4. /etc/systemd/network/25-wireless.link
Here's an overly complex example that shows the use of a large
number of [Match] and [Link] settings.
[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