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SYSTEMD.LINK(5) systemd.link SYSTEMD.LINK(5)
systemd.link - Network device configuration
link.link
A plain ini-style text file that encodes configuration for
matching network devices, used by systemd-udevd(8) and in
particular its net_setup_link builtin. See systemd.syntax(7) for a
general description of the syntax.
Note that some distributions may incorporate .link files in their
early boot facilities (e.g. by including copies of the .link files
in initramfs). As such it may be necessary to take manual steps to
ensure that any local changes are consistent with early-boot
storage facilities. The relevant distribution-specific
documentation should be consulted.
The .link files are read from the files located in the system
network directory /usr/lib/systemd/network and
/usr/local/lib/systemd/network [1], 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 alphanumeric order,
regardless of the directories in which they live. However, files
with identical filenames replace each other. It is recommended
that each filename is prefixed with a number smaller than "70"
(e.g. 10-eth0.link). Otherwise, the default .link files or those
generated by systemd-network-generator.service(8) may take
precedence over user configured files. 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. As a
special case, an empty file (file size 0) or symlink with the same
name pointing to /dev/null disables the configuration file
entirely (it is "masked").
Along with the link file foo.link, a "drop-in" directory
foo.link.d/ may exist. All files with the suffix ".conf" from this
directory will be merged in the alphanumeric order and parsed
after the main file itself has been parsed. This is useful to
alter or add configuration settings, without having to modify the
main configuration file. Each drop-in file must have appropriate
section headers.
In addition to /etc/systemd/network, drop-in ".d" directories can
be placed in /usr/lib/systemd/network or /run/systemd/network
directories. Drop-in files in /etc/ take precedence over those in
/run/ which in turn take precedence over those in /usr/lib/.
Drop-in files under any of these directories take precedence over
the main link file wherever located.
The link file contains a [Match] section, which determines if a
given link file may be applied to a given device, as well as 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. Note that a default file 99-default.link is
shipped by the system. Any user-supplied .link should hence have a
lexically earlier name to be considered at all.
See udevadm(8) for diagnosing problems with .link files.
A link file is said to match an interface if all matches specified
by the [Match] section are satisfied. When a link file does not
contain valid settings in [Match] section, then the file will
match all interfaces and systemd-udevd warns about that. Hint: to
avoid the warning and to make it clear that all interfaces shall
be matched, add the following:
OriginalName=*
The first (in alphanumeric order) of the link files that matches a
given interface is applied, all later files are ignored, even if
they match as well. The following keys are accepted:
MACAddress=
A whitespace-separated list of hardware addresses. The
acceptable formats are:
colon-delimited hexadecimal
Each field must be one byte. E.g. "12:34:56:78:90:ab" or
"AA:BB:CC:DD:EE:FF".
Added in version 250.
hyphen-delimited hexadecimal
Each field must be one byte. E.g. "12-34-56-78-90-ab" or
"AA-BB-CC-DD-EE-FF".
Added in version 250.
dot-delimited hexadecimal
Each field must be two bytes. E.g. "1234.5678.90ab" or
"AABB.CCDD.EEFF".
Added in version 250.
IPv4 address format
E.g. "127.0.0.1" or "192.168.0.1".
Added in version 250.
IPv6 address format
E.g. "2001:0db8:85a3::8a2e:0370:7334" or "::1".
Added in version 250.
The total length of each MAC address must be 4 (for IPv4
tunnel), 6 (for Ethernet), 16 (for IPv6 tunnel), or 20 (for
InfiniBand). 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. Defaults to unset.
Added in version 211.
PermanentMACAddress=
A whitespace-separated list of hardware's permanent addresses.
While MACAddress= matches the device's current MAC address,
this matches the device's permanent MAC address, which may be
different from the current one. Use full colon-, hyphen- or
dot-delimited hexadecimal, or IPv4 or IPv6 address format.
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.
Defaults to unset.
Added in version 245.
Path=
A whitespace-separated list of shell-style globs matching the
persistent path, as exposed by the udev property ID_PATH.
Added in version 211.
Driver=
A whitespace-separated list of shell-style globs matching the
driver currently bound to the device, as exposed by the udev
property ID_NET_DRIVER of its parent device, or if that is not
set, the driver as exposed by ethtool -i of the device itself.
If the list is prefixed with a "!", the test is inverted.
Added in version 211.
Type=
A whitespace-separated list of shell-style globs matching the
device type, as exposed by networkctl list. If the list is
prefixed with a "!", the test is inverted. Some valid values
are "ether", "loopback", "wlan", "wwan". Valid types are named
either from the udev "DEVTYPE" attribute, or "ARPHRD_" macros
in linux/if_arp.h, so this is not comprehensive.
Added in version 211.
Kind=
A whitespace-separated list of shell-style globs matching the
device kind, as exposed by networkctl status INTERFACE or ip
-d link show INTERFACE. If the list is prefixed with a "!",
the test is inverted. Some valid values are "bond", "bridge",
"gre", "tun", "veth". Valid kinds are given by netlink's
"IFLA_INFO_KIND" attribute, so this is not comprehensive.
Added in version 251.
Property=
A whitespace-separated list of udev property names with their
values after equals sign ("="). If multiple properties are
specified, the test results are ANDed. If the list is prefixed
with a "!", the test is inverted. If a value contains white
spaces, then please quote whole key and value pair. If a value
contains quotation, then please escape the quotation with "\".
Example: if a .link file has the following:
Property=ID_MODEL_ID=9999 "ID_VENDOR_FROM_DATABASE=vendor name" "KEY=with \"quotation\""
then, the .link file matches only when an interface has all
the above three properties.
Added in version 243.
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.
Added in version 218.
Host=
Matches against the hostname or machine ID of the host. See
ConditionHost= in systemd.unit(5) for details. When prefixed
with an exclamation mark ("!"), the result is negated. If an
empty string is assigned, the previously assigned value is
cleared.
Added in version 211.
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. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 211.
KernelCommandLine=
Checks whether a specific kernel command line option is set.
See ConditionKernelCommandLine= in systemd.unit(5) for
details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 211.
KernelVersion=
Checks whether the kernel version (as reported by uname -r)
matches a certain expression. See ConditionKernelVersion= in
systemd.unit(5) for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 237.
Version=
Checks whether a software version matches a certain
expression. See ConditionVersion= in systemd.unit(5) for
details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 258.
Credential=
Checks whether the specified credential was passed to the
systemd-udevd.service service. See System and Service
Credentials[2] for details. When prefixed with an exclamation
mark ("!"), the result is negated. If an empty string is
assigned, the previously assigned value is cleared.
Added in version 252.
Architecture=
Checks whether the system is running on a specific
architecture. See ConditionArchitecture= in systemd.unit(5)
for details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 211.
Firmware=
Checks whether the system is running on a machine with the
specified firmware. See ConditionFirmware= in systemd.unit(5)
for details. When prefixed with an exclamation mark ("!"), the
result is negated. If an empty string is assigned, the
previously assigned value is cleared.
Added in version 249.
The [Link] section accepts the following keys:
Description=
A description of the device.
Added in version 211.
Property=
Set specified udev properties. This takes space separated list
of key-value pairs concatenated with equal sign ("=").
Example:
Property=HOGE=foo BAR=baz
This option supports simple specifier expansion, see the
Specifiers section below. This option can be specified
multiple times. If an empty string is assigned, then the all
previous assignments are cleared.
This setting is useful to configure the "ID_NET_MANAGED_BY="
property which declares which network management service shall
manage the interface, which is respected by
systemd-networkd(8) and others. Use
Property=ID_NET_MANAGED_BY=io.systemd.Network
to declare explicitly that systemd-networkd shall manage the
interface, or set the property to something else to declare
explicitly it shall not do so. See systemd.network(5) for
details how this property is used to match interface names.
Added in version 256.
ImportProperty=
Import specified udev properties from the saved database. This
takes space separated list of property names. Example:
ImportProperty=HOGE BAR
This option supports simple specifier expansion, see the
Specifiers section below. This option can be specified
multiple times. If an empty string is assigned, then the all
previous assignments are cleared.
If the same property is also set in Property= in the above,
then the imported property value will be overridden by the
value specified in Property=.
Added in version 256.
UnsetProperty=
Unset specified udev properties. This takes space separated
list of property names. Example:
UnsetProperty=HOGE BAR
This option supports simple specifier expansion, see the
Specifiers section below. This option can be specified
multiple times. If an empty string is assigned, then the all
previous assignments are cleared.
This setting is applied after ImportProperty= and Property=
are applied. Hence, if the same property is specified in
ImportProperty= or Property=, then the imported or specified
property value will be ignored, and the property will be
unset.
Added in version 256.
Alias=
The ifalias interface property is set to this value.
Added in version 211.
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.
Added in version 211.
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.
Added in version 211.
none
Keeps the MAC address assigned by the kernel. Or use the
MAC address specified in MACAddress=.
Added in version 227.
An empty string assignment is equivalent to setting "none".
Added in version 211.
MACAddress=
The interface MAC address to use. For this setting to take
effect, MACAddressPolicy= must either be unset, empty, or
"none".
Added in version 211.
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(7),
rule to set NAME. 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.
Added in version 216.
database
The name is set based on entries in the udev's Hardware
Database with the key ID_NET_NAME_FROM_DATABASE.
Added in version 211.
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).
Added in version 211.
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).
Added in version 211.
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).
Added in version 211.
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).
Added in version 211.
keep
If the device already had a name given by userspace (as
part of creation of the device or a rename), keep it.
Added in version 241.
Added in version 211.
Name=
The interface name to use. This option has lower precedence
than NamePolicy=, so for this setting to take effect,
NamePolicy= must either be unset, empty, disabled, or all
policies configured there must fail. Also see the example
below with "Name=dmz0".
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".
Interface names must have a minimum length of 1 character and
a maximum length of 15 characters, and may contain any 7bit
ASCII character, with the exception of control characters,
":", "/" and "%". While "." is an allowed character, it is
recommended to avoid it when naming interfaces as various
tools (such as resolvconf(1)) use it as separator character.
Also, fully numeric interface names are not allowed (in order
to avoid ambiguity with interface specification by numeric
indexes), nor are the special strings ".", "..", "all" and
"default".
Added in version 211.
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.
Added in version 245.
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.
Alternative interface names may be used to identify interfaces
in various tools. In contrast to the primary name (as
configured with Name= above) there may be multiple alternative
names referring to the same interface. Alternative names may
have a maximum length of 127 characters, in contrast to the 15
allowed for the primary interface name, but otherwise are
subject to the same naming constraints.
Added in version 245.
TransmitQueues=
Specifies the device's number of transmit queues. An integer
in the range 1...4096. When unset, the kernel's default will
be used.
Added in version 248.
ReceiveQueues=
Specifies the device's number of receive queues. An integer in
the range 1...4096. When unset, the kernel's default will be
used.
Added in version 248.
TransmitQueueLength=
Specifies the transmit queue length of the device in number of
packets. An unsigned integer in the range 0...4294967294. When
unset, the kernel's default will be used.
Added in version 248.
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.
Added in version 211.
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.
Added in version 211.
Duplex=
The duplex mode to set for the device. The accepted values are
half and full.
Added in version 211.
AutoNegotiation=
Takes a boolean. If set to yes, automatic negotiation of
transmission parameters is enabled. Autonegotiation is a
procedure by which two connected ethernet devices choose
common transmission parameters, such as speed, duplex mode,
and flow control. When unset, the kernel's default will be
used.
Note that if autonegotiation is enabled, speed and duplex
settings are read-only. If autonegotiation is disabled, speed
and duplex settings are writable if the driver supports
multiple link modes.
Added in version 233.
WakeOnLan=
The Wake-on-LAN policy to set for the device. Takes the
special value "off" which disables Wake-on-LAN, or space
separated list of the following words:
phy
Wake on PHY activity.
Added in version 211.
unicast
Wake on unicast messages.
Added in version 235.
multicast
Wake on multicast messages.
Added in version 235.
broadcast
Wake on broadcast messages.
Added in version 235.
arp
Wake on ARP.
Added in version 235.
magic
Wake on receipt of a magic packet.
Added in version 211.
secureon
Enable SecureOn password for MagicPacket. Implied when
WakeOnLanPassword= is specified. If specified without
WakeOnLanPassword= option, then the password is read from
the credential "LINK.link.wol.password" (e.g.,
"60-foo.link.wol.password"), and if the credential not
found, then read from "wol.password". See
ImportCredential=/LoadCredential=/SetCredential= in
systemd.exec(5) for details. The password in the
credential, must be 6 bytes in hex format with each byte
separated by a colon (":") like an Ethernet MAC address,
e.g., "aa:bb:cc:dd:ee:ff".
Added in version 235.
Defaults to unset, and the device's default will be used. This
setting can be specified multiple times. If an empty string is
assigned, then the all previous assignments are cleared.
Added in version 211.
WakeOnLanPassword=
Specifies the SecureOn password for MagicPacket. Takes an
absolute path to a regular file or an AF_UNIX stream socket,
or the plain password. When a path to a regular file is
specified, the password is read from it. When an AF_UNIX
stream socket is specified, a connection is made to it and the
password is read from it. The password must be 6 bytes in hex
format with each byte separated by a colon (":") like an
Ethernet MAC address, e.g., "aa:bb:cc:dd:ee:ff". This implies
WakeOnLan=secureon. Defaults to unset, and the current value
will not be changed.
Added in version 250.
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.
Added in version 234.
aui
Attachment Unit Interface (AUI). Normally used with hubs.
Added in version 234.
bnc
An Ethernet interface using BNC connectors and co-axial
cable.
Added in version 234.
mii
An Ethernet interface using a Media Independent Interface
(MII).
Added in version 234.
fibre
An Ethernet interface using Optical Fibre as the medium.
Added in version 234.
Added in version 234.
Advertise=
This sets what speeds and duplex modes of operation are
advertised for auto-negotiation. This implies
"AutoNegotiation=yes". The supported values are:
Table 1. Supported advertise values
┌────────────────────────────┬──────────────┬─────────────┐
│ Advertise │ Speed (Mbps) │ Duplex Mode │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset-full │ 10 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset1brr-full │ 10 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset1l-full │ 10 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset1s-full │ 10 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset-half │ 10 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset1s-half │ 10 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 10baset1s-p2mp-half │ 10 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 100basefx-full │ 100 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100baset-full │ 100 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100baset1-full │ 100 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100basefx-half │ 100 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 100baset-half │ 100 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 1000basekx-full │ 1000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 1000baset-full │ 1000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 1000baset1-full │ 1000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 1000basex-full │ 1000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 1000baset-half │ 1000 │ half │
├────────────────────────────┼──────────────┼─────────────┤
│ 2500baset-full │ 2500 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 2500basex-full │ 2500 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 5000baset-full │ 5000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000baser-fec │ 10000 │ │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000basecr-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000baseer-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000basekr-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000basekx4-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000baselr-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000baselrm-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000basesr-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 10000baset-full │ 10000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 20000basekr2-full │ 20000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 20000basemld2-full │ 20000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 25000basecr-full │ 25000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 25000basekr-full │ 25000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 25000basesr-full │ 25000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 40000basecr4-full │ 40000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 40000basekr4-full │ 40000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 40000baselr4-full │ 40000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 40000basesr4-full │ 40000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basecr-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basecr2-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basedr-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basekr-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basekr2-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000baselr-er-fr-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basesr-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 50000basesr2-full │ 50000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 56000basecr4-full │ 56000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 56000basekr4-full │ 56000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 56000baselr4-full │ 56000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 56000basesr4-full │ 56000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basecr-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basecr2-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basecr4-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basedr-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basedr2-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basekr-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basekr2-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basekr4-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000baselr-er-fr-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000baselr2-er2-fr2-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000baselr4-er4-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basesr-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basesr2-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 100000basesr4-full │ 100000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basecr-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basecr2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basecr4-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basedr-2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basedr-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basedr2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basedr4-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basekr-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basekr2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basekr4-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000baselr2-er2-fr2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000baselr4-er4-fr4-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basesr-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basesr2-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basesr4-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 200000basevr-full │ 200000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basecr2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basecr4-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basecr8-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basedr2-2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basedr2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basedr4-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basedr8-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basekr2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basekr4-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basekr8-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000baselr4-er4-fr4-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000baselr8-er8-fr8-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basesr2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basesr4-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basesr8-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 400000basevr2-full │ 400000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basecr4-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basecr8-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basedr4-2-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basedr4-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basedr8-2-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basedr8-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basekr4-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basekr8-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basesr4-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basesr8-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basevr4-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ 800000basevr8-full │ 800000 │ full │
├────────────────────────────┼──────────────┼─────────────┤
│ asym-pause │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ aui │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ autonegotiation │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ backplane │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ bnc │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ fec-baser │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ fec-llrs │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ fec-none │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ fec-rs │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ fibre │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ mii │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ pause │ │ │
├────────────────────────────┼──────────────┼─────────────┤
│ tp │ │ │
└────────────────────────────┴──────────────┴─────────────┘
By default, this is unset, i.e. all possible modes will be
advertised. This option may be specified more than once, in
which case all specified speeds and modes are advertised. If
the empty string is assigned to this option, the list is
reset, and all prior assignments have no effect.
Added in version 240.
ReceiveChecksumOffload=
Takes a boolean. If set to true, hardware offload for
checksumming of ingress network packets is enabled. When
unset, the kernel's default will be used.
Added in version 245.
TransmitChecksumOffload=
Takes a boolean. If set to true, hardware offload for
checksumming of egress network packets is enabled. When unset,
the kernel's default will be used.
Added in version 245.
TCPSegmentationOffload=
Takes a boolean. If set to true, TCP Segmentation Offload
(TSO) is enabled. When unset, the kernel's default will be
used.
Added in version 232.
TCP6SegmentationOffload=
Takes a boolean. If set to true, TCP6 Segmentation Offload
(tx-tcp6-segmentation) is enabled. When unset, the kernel's
default will be used.
Added in version 235.
GenericSegmentationOffload=
Takes a boolean. If set to true, Generic Segmentation Offload
(GSO) is enabled. When unset, the kernel's default will be
used.
Added in version 232.
PartialGenericSegmentationOffload=
Takes a boolean. If set to true, Partial Generic Segmentation
Offload (GSO_Partial) is enabled. See Partial Generic
Segmentation Offload[3] for more details. When unset, the
kernel's default will be used.
Added in version 258.
GenericReceiveOffload=
Takes a boolean. If set to true, Generic Receive Offload (GRO)
is enabled. When unset, the kernel's default will be used.
Added in version 232.
GenericReceiveOffloadHardware=
Takes a boolean. If set to true, hardware accelerated Generic
Receive Offload (GRO) is enabled. When unset, the kernel's
default will be used.
Added in version 250.
LargeReceiveOffload=
Takes a boolean. If set to true, Large Receive Offload (LRO)
is enabled. When unset, the kernel's default will be used.
Added in version 232.
ReceivePacketSteeringCPUMask=
Configures Receive Packet Steering (RPS) list of CPUs to which
RPS may forward traffic. Takes a list of CPU indices or ranges
separated by either whitespace or commas. Alternatively, takes
the special value "all", which will include all available CPUs
in the mask. CPU ranges are specified by the lower and upper
CPU indices separated by a dash (e.g. "2-6"). This option may
be specified more than once, in which case the specified list
of CPU ranges are merged. If an empty string is assigned, the
list is reset, all assignments prior to this will have no
effect. Defaults to unset and RPS CPU list is unchanged. To
disable RPS when it was previously enabled, use the special
value "disable".
Added in version 256.
ReceiveVLANCTAGHardwareAcceleration=
Takes a boolean. If set to true, receive VLAN CTAG hardware
acceleration is enabled. When unset, the kernel's default will
be used.
Added in version 250.
TransmitVLANCTAGHardwareAcceleration=
Takes a boolean. If set to true, transmit VLAN CTAG hardware
acceleration is enabled. When unset, the kernel's default will
be used.
Added in version 250.
ReceiveVLANCTAGFilter=
Takes a boolean. If set to true, receive filtering on VLAN
CTAGs is enabled. When unset, the kernel's default will be
used.
Added in version 250.
TransmitVLANSTAGHardwareAcceleration=
Takes a boolean. If set to true, transmit VLAN STAG hardware
acceleration is enabled. When unset, the kernel's default will
be used.
Added in version 250.
NTupleFilter=
Takes a boolean. If set to true, receive N-tuple filters and
actions are enabled. When unset, the kernel's default will be
used.
Added in version 250.
ReceiveFCS=
Takes a boolean. If set to true, pass the Frame Check Sequence
(FCS) value up the stack without trimming it, and allow
userspace to calculate error rate or link health. When unset,
the kernel's default will be used.
Added in version 258.
ReceiveAll=
Takes a boolean. If set to true, allow the interface to also
receive damaged ethernet frames. When unset, the kernel's
default will be used.
Added in version 258.
RxChannels=, TxChannels=, OtherChannels=, CombinedChannels=
Specifies the number of receive, transmit, other, or combined
channels, respectively. Takes an unsigned integer in the range
1...4294967295 or "max". If set to "max", the advertised
maximum value of the hardware will be used. When unset, the
number will not be changed. Defaults to unset.
Added in version 239.
RxBufferSize=, RxMiniBufferSize=, RxJumboBufferSize=,
TxBufferSize=
Specifies the maximum number of pending packets in the NIC
receive buffer, mini receive buffer, jumbo receive buffer, or
transmit buffer, respectively. Takes an unsigned integer in
the range 1...4294967295 or "max". If set to "max", the
advertised maximum value of the hardware will be used. When
unset, the number will not be changed. Defaults to unset.
Added in version 244.
RxFlowControl=
Takes a boolean. When set, enables receive flow control, also
known as the ethernet receive PAUSE message (generate and send
ethernet PAUSE frames). When unset, the kernel's default will
be used.
Added in version 246.
TxFlowControl=
Takes a boolean. When set, enables transmit flow control, also
known as the ethernet transmit PAUSE message (respond to
received ethernet PAUSE frames). When unset, the kernel's
default will be used.
Added in version 246.
AutoNegotiationFlowControl=
Takes a boolean. When set, auto negotiation enables the
interface to exchange state advertisements with the connected
peer so that the two devices can agree on the ethernet PAUSE
configuration. When unset, the kernel's default will be used.
Added in version 246.
GenericSegmentOffloadMaxBytes=
Specifies the maximum size of a Generic Segment Offload (GSO)
packet the device should accept. The usual suffixes K, M, G
are supported and are understood to the base of 1024. An
unsigned integer in the range 1...65536. Defaults to unset.
Added in version 248.
GenericSegmentOffloadMaxSegments=
Specifies the maximum number of Generic Segment Offload (GSO)
segments the device should accept. An unsigned integer in the
range 1...65535. Defaults to unset.
Added in version 248.
UseAdaptiveRxCoalesce=, UseAdaptiveTxCoalesce=
Boolean properties that, when set, enable/disable adaptive
Rx/Tx coalescing if the hardware supports it. When unset, the
kernel's default will be used.
Added in version 250.
RxCoalesceSec=, RxCoalesceIrqSec=, RxCoalesceLowSec=,
RxCoalesceHighSec=, TxCoalesceSec=, TxCoalesceIrqSec=,
TxCoalesceLowSec=, TxCoalesceHighSec=
These properties configure the delay before Rx/Tx interrupts
are generated after a packet is sent/received. The "Irq"
properties come into effect when the host is servicing an IRQ.
The "Low" and "High" properties come into effect when the
packet rate drops below the low packet rate threshold or
exceeds the high packet rate threshold respectively if
adaptive Rx/Tx coalescing is enabled. When unset, the kernel's
defaults will be used.
Added in version 250.
RxMaxCoalescedFrames=, RxMaxCoalescedIrqFrames=,
RxMaxCoalescedLowFrames=, RxMaxCoalescedHighFrames=,
TxMaxCoalescedFrames=, TxMaxCoalescedIrqFrames=,
TxMaxCoalescedLowFrames=, TxMaxCoalescedHighFrames=
These properties configure the maximum number of frames that
are sent/received before a Rx/Tx interrupt is generated. The
"Irq" properties come into effect when the host is servicing
an IRQ. The "Low" and "High" properties come into effect when
the packet rate drops below the low packet rate threshold or
exceeds the high packet rate threshold respectively if
adaptive Rx/Tx coalescing is enabled. When unset, the kernel's
defaults will be used.
Added in version 250.
CoalescePacketRateLow=, CoalescePacketRateHigh=
These properties configure the low and high packet rate
(expressed in packets per second) threshold respectively and
are used to determine when the corresponding coalescing
settings for low and high packet rates come into effect if
adaptive Rx/Tx coalescing is enabled. If unset, the kernel's
defaults will be used.
Added in version 250.
CoalescePacketRateSampleIntervalSec=
Configures how often to sample the packet rate used for
adaptive Rx/Tx coalescing. This property cannot be zero. This
lowest time granularity supported by this property is seconds.
Partial seconds will be rounded up before being passed to the
kernel. If unset, the kernel's default will be used.
Added in version 250.
StatisticsBlockCoalesceSec=
How long to delay driver in-memory statistics block updates.
If the driver does not have an in-memory statistic block, this
property is ignored. This property cannot be zero. If unset,
the kernel's default will be used.
Added in version 250.
MDI=
Specifies the medium dependent interface (MDI) mode for the
interface. A MDI describes the interface from a physical layer
implementation to the physical medium used to carry the
transmission. Takes one of the following words: "straight" (or
equivalently: "mdi"), "crossover" (or equivalently: "mdi-x",
"mdix"), and "auto". When "straight", the MDI straight through
mode will be used. When "crossover", the MDI crossover (MDI-X)
mode will be used. When "auto", the MDI status is
automatically detected. Defaults to unset, and the kernel's
default will be used.
Added in version 251.
SR-IOVVirtualFunctions=
Specifies the number of SR-IOV virtual functions. Takes an
integer in the range 0...2147483647. Defaults to unset, and
automatically determined from the values specified in the
VirtualFunction= settings in the [SR-IOV] sections.
Added in version 251.
SR-IOV provides the ability to partition a single physical PCI
resource into virtual PCI functions which can then be e.g.
injected into a VM. In the case of network VFs, SR-IOV reduces
latency and CPU utilisation for north-south network traffic (that
is, traffic with endpoints outside the host machine), by allowing
traffic to bypass the host machine’s network stack.
The presence of an [SR-IOV] section in a .link file will cause the
creation and configuration of the specified virtual function.
Within a .network file, the specified virtual function will be
configured, but must already exist. Specify several [SR-IOV]
sections to configure several SR-IOVs.
The [SR-IOV] section accepts the following keys.
VirtualFunction=
Specifies a Virtual Function (VF), lightweight PCIe function
designed solely to move data in and out. Takes an integer in
the range 0...2147483646. This option is compulsory.
Added in version 251.
VLANId=
Specifies VLAN ID of the virtual function. Takes an integer in
the range 1...4095.
Added in version 251.
QualityOfService=
Specifies quality of service of the virtual function. Takes an
integer in the range 1...4294967294.
Added in version 251.
VLANProtocol=
Specifies VLAN protocol of the virtual function. Takes
"802.1Q" or "802.1ad".
Added in version 251.
MACSpoofCheck=
Takes a boolean. Controls the MAC spoof checking. When unset,
the kernel's default will be used.
Added in version 251.
QueryReceiveSideScaling=
Takes a boolean. Toggle the ability of querying the receive
side scaling (RSS) configuration of the virtual function (VF).
The VF RSS information like RSS hash key may be considered
sensitive on some devices where this information is shared
between VF and the physical function (PF). When unset, the
kernel's default will be used.
Added in version 251.
Trust=
Takes a boolean. Allows one to set trust mode of the virtual
function (VF). When set, VF users can set a specific feature
which may impact security and/or performance. When unset, the
kernel's default will be used.
Added in version 251.
LinkState=
Allows one to set the link state of the virtual function (VF).
Takes a boolean or a special value "auto". Setting to "auto"
means a reflection of the physical function (PF) link state,
"yes" lets the VF to communicate with other VFs on this host
even if the PF link state is down, "no" causes the hardware to
drop any packets sent by the VF. When unset, the kernel's
default will be used.
Added in version 251.
MACAddress=
Specifies the MAC address for the virtual function.
Added in version 251.
The [EnergyEfficientEthernet] section controls the Energy
Efficient Ethernet (EEE) feature of the interface, and accepts the
following keys.
Enable=
Takes a boolean argument. When true, the Energy Efficient
Ethernet (EEE) feature will be enabled on the interface.
Defaults to unset, and the enablement of EEE will be
unchanged.
Added in version 258.
TxLowPowerIdle=
Takes a boolean argument. When true, the transmit Low Power
Idle (Tx-LPI) mode of the Energy Efficient Ethernet feature
will be enabled on the interface. Defaults to unset, and the
enablement of the mode will be unchanged.
Added in version 258.
TxLowPowerIdleSec=
Takes a timespan. This configures how long the interface
should not enter the Low Power Idle mode after transmission.
If it is too short, may decrease performance. If it is too
long, may not gain energy saving. Defaults to unset, and the
timespan will be unchanged.
Added in version 258.
LinkMode=
Takes a list of link modes, e.g. "1000baset-full". See the
table for Advertise= setting in [Link] section in the above
for possible values. This configures the Energy Efficient
Ethernet capable connection modes to be advertised. Defaults
to unset, and the advertised modes will be unchanged.
Added in version 258.
Some settings resolve specifiers which may be used to write
generic unit files referring to runtime or unit parameters that
are replaced when the unit files are loaded. Specifiers must be
known and resolvable for the setting to be valid. The following
specifiers are understood:
Table 2. Specifiers available in unit files
┌───────────┬──────────────────┬────────────────────────┐
│ Specifier │ Meaning │ Details │
├───────────┼──────────────────┼────────────────────────┤
│ "%a" │ Architecture │ A short string │
│ │ │ identifying the │
│ │ │ architecture of │
│ │ │ the local system. │
│ │ │ A string such as │
│ │ │ x86, x86-64 or │
│ │ │ arm64. See the │
│ │ │ architectures │
│ │ │ defined for │
│ │ │ ConditionArchitecture= │
│ │ │ in systemd.unit(5) │
│ │ │ for a full list. │
├───────────┼──────────────────┼────────────────────────┤
│ "%A" │ Operating system │ The operating system │
│ │ image version │ image version │
│ │ │ identifier of the │
│ │ │ running system, as │
│ │ │ read from the │
│ │ │ IMAGE_VERSION= field │
│ │ │ of /etc/os-release. If │
│ │ │ not set, resolves to │
│ │ │ an empty string. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%b" │ Boot ID │ The boot ID of the │
│ │ │ running system, │
│ │ │ formatted as string. │
│ │ │ See random(4) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%B" │ Operating system │ The operating system │
│ │ build ID │ build identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ BUILD_ID= field of │
│ │ │ /etc/os-release. If │
│ │ │ not set, resolves to │
│ │ │ an empty string. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%H" │ Host name │ The hostname of the │
│ │ │ running system. │
├───────────┼──────────────────┼────────────────────────┤
│ "%l" │ Short host name │ The hostname of the │
│ │ │ running system, │
│ │ │ truncated at the first │
│ │ │ dot to remove any │
│ │ │ domain component. │
├───────────┼──────────────────┼────────────────────────┤
│ "%m" │ Machine ID │ The machine ID of the │
│ │ │ running system, │
│ │ │ formatted as string. │
│ │ │ See machine-id(5) for │
│ │ │ more information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%M" │ Operating system │ The operating system │
│ │ image identifier │ image identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ IMAGE_ID= field of │
│ │ │ /etc/os-release. If │
│ │ │ not set, resolves to │
│ │ │ an empty string. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%o" │ Operating system │ The operating system │
│ │ ID │ identifier of the │
│ │ │ running system, as │
│ │ │ read from the ID= │
│ │ │ field of │
│ │ │ /etc/os-release. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%q" │ Pretty host name │ The pretty hostname of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ PRETTY_HOSTNAME= field │
│ │ │ of /etc/machine-info. │
│ │ │ If not set, resolves │
│ │ │ to the short hostname. │
│ │ │ See machine-info(5) │
│ │ │ for more information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%T" │ Directory for │ This is either /tmp or │
│ │ temporary files │ the path "$TMPDIR", │
│ │ │ "$TEMP" or "$TMP" are │
│ │ │ set to. (Note that the │
│ │ │ directory may be │
│ │ │ specified without a │
│ │ │ trailing slash.) │
├───────────┼──────────────────┼────────────────────────┤
│ "%v" │ Kernel release │ Identical to uname -r │
│ │ │ output. │
├───────────┼──────────────────┼────────────────────────┤
│ "%V" │ Directory for │ This is either │
│ │ larger and │ /var/tmp or the path │
│ │ persistent │ "$TMPDIR", "$TEMP" or │
│ │ temporary files │ "$TMP" are set to. │
│ │ │ (Note that the │
│ │ │ directory may be │
│ │ │ specified without a │
│ │ │ trailing slash.) │
├───────────┼──────────────────┼────────────────────────┤
│ "%w" │ Operating system │ The operating system │
│ │ version ID │ version identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ VERSION_ID= field of │
│ │ │ /etc/os-release. If │
│ │ │ not set, resolves to │
│ │ │ an empty string. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
├───────────┼──────────────────┼────────────────────────┤
│ "%W" │ Operating system │ The operating system │
│ │ variant ID │ variant identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ VARIANT_ID= field of │
│ │ │ /etc/os-release. If │
│ │ │ not set, resolves to │
│ │ │ an empty string. See │
│ │ │ os-release(5) for more │
│ │ │ information. │
└───────────┴──────────────────┴────────────────────────┘
Example 1. /usr/lib/systemd/network/99-default.link
The link file 99-default.link that is shipped with systemd defines
the default policies for the interface name, alternative names,
and MAC address of links.
[Match]
OriginalName=*
[Link]
NamePolicy=keep kernel database onboard slot path
AlternativeNamesPolicy=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
NamePolicy= is not set, so Name= takes effect. We use the "10-"
prefix to order this file early in the list. Note that it needs to
be before 99-default.link, i.e. it needs a numerical prefix, to
have any effect at all.
Example 3. (Re-)applying a .link file to an interface
After a new .link file has been created, or an existing .link file
modified, the new settings may be applied to the matching
interface with the following commands:
$ sudo udevadm control --reload
$ sudo ip link set eth0 down
$ sudo udevadm trigger --verbose --settle --action add /sys/class/net/eth0
You may also need to stop the service that manages the network
interface, e.g. systemd-networkd.service(8) or
NetworkManager.service before the above operation, and then
restart the service after that. For more details about udevadm
command, see udevadm(8).
Example 4. Debugging NamePolicy= assignments
$ sudo SYSTEMD_LOG_LEVEL=debug udevadm test-builtin net_setup_link /sys/class/net/hub0
...
Parsed configuration file /usr/lib/systemd/network/99-default.link
Parsed configuration file /etc/systemd/network/10-eth0.link
ID_NET_DRIVER=cdc_ether
Config file /etc/systemd/network/10-eth0.link applies to device hub0
link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
hub0: Device has name_assign_type=4
Using default interface naming scheme 'v240'.
hub0: Policies did not yield a name, using specified Name=hub0.
ID_NET_LINK_FILE=/etc/systemd/network/10-eth0.link
ID_NET_NAME=hub0
...
Explicit Name= configuration wins in this case.
sudo SYSTEMD_LOG_LEVEL=debug udevadm test-builtin net_setup_link /sys/class/net/enp0s31f6
...
Parsed configuration file /usr/lib/systemd/network/99-default.link
Parsed configuration file /etc/systemd/network/10-eth0.link
Created link configuration context.
ID_NET_DRIVER=e1000e
Config file /usr/lib/systemd/network/99-default.link applies to device enp0s31f6
link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
enp0s31f6: Device has name_assign_type=4
Using default interface naming scheme 'v240'.
enp0s31f6: Policy *keep*: keeping existing userspace name
enp0s31f6: Device has addr_assign_type=0
enp0s31f6: MAC on the device already matches policy *persistent*
ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
...
In this case, the interface was already renamed, so the keep
policy specified as the first option in 99-default.link means that
the existing name is preserved. If keep was removed, or if were in
boot before the renaming has happened, we might get the following
instead:
enp0s31f6: Policy *path* yields "enp0s31f6".
enp0s31f6: Device has addr_assign_type=0
enp0s31f6: MAC on the device already matches policy *persistent*
ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
ID_NET_NAME=enp0s31f6
...
Please note that the details of output are subject to change.
Example 5. /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 6. /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
systemd-udevd.service(8), udevadm(8), systemd.netdev(5),
systemd.network(5), systemd-network-generator.service(8)
1. 💣💥🧨💥💥💣 Please note that those configuration files must
be available at all times. If /usr/local/ is a separate
partition, it may not be available during early boot, and must
not be used for configuration.
2. System and Service Credentials
https://systemd.io/CREDENTIALS
3. Partial Generic Segmentation Offload
https://docs.kernel.org/networking/segmentation-offloads.html#partial-generic-segmentation-offload
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SYSTEMD.LINK(5)
Pages that refer to this page: networkctl(1), systemd.netdev(5), systemd.network(5), systemd.directives(7), systemd.index(7), systemd.net-naming-scheme(7), systemd.syntax(7), systemd.system-credentials(7), udev(7), systemd-networkd.service(8), systemd-network-generator.service(8), systemd-udevd.service(8)
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