# systemd.link

## NAME



           systemd.link - Network device configuration
    


## SYNOPSIS



           _link_.link
    


## DESCRIPTION



           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.
    


## [MATCH] SECTION OPTIONS



           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.
    


## [LINK] SECTION OPTIONS



           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] SECTION OPTIONS



           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.
    


## [ENERGYEFFICIENTETHERNET] SECTION OPTIONS



           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.
    


## SPECIFIERS



           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.           │
           └───────────┴──────────────────┴────────────────────────┘
    


## EXAMPLES



           **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
    


## NOTES



            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
    


* * *