udevadm(8) for diagnosing problems with .link files.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:Example 3. /etc/systemd/network/10-internet.link This example assigns the fixed name "internet0" to the interface with the device path "pci-0000:00:1a.0-*":Example 4. /etc/systemd/network/25-wireless.link Here's an overly complex example that shows the use of a large number of [Match] and [Link] settings.systemd-udevd.service(8), udevadm(8), systemd.netdev(5), systemd.network(5)
The hardware address.OriginalName=
A whitespace-separated list of shell-style globs matching the device name, as exposed by the udev property "INTERFACE". This cannot be used to match on names that have already been changed from userspace. Caution is advised when matching on kernel-assigned names, as they are known to be unstable between reboots.Path=
A whitespace-separated list of shell-style globs matching the persistent path, as exposed by the udev property "ID_PATH".Driver=
A whitespace-separated list of shell-style globs matching the driver currently bound to the device, as exposed by the udev property "DRIVER" of its parent device, or if that is not set, the driver as exposed by "ethtool -i" of the device itself.Type=
A whitespace-separated list of shell-style globs matching the device type, as exposed by the udev property "DEVTYPE".Host=
Matches against the hostname or machine ID of the host. See "ConditionHost=" in systemd.unit(5) for details.Virtualization=
Checks whether the system is executed in a virtualized environment and optionally test whether it is a specific implementation. See "ConditionVirtualization=" in systemd.unit(5) for details.KernelCommandLine=
Checks whether a specific kernel command line option is set (or if prefixed with the exclamation mark unset). See "ConditionKernelCommandLine=" in systemd.unit(5) for details.KernelVersion=
Checks whether the kernel version (as reported by uname -r) matches a certain expression (or if prefixed with the exclamation mark does not match it). See "ConditionKernelVersion=" in systemd.unit(5) for details.Architecture=
Checks whether the system is running on a specific architecture. See "ConditionArchitecture=" in systemd.unit(5) for details.
A description of the device.Alias=
The "ifalias" is set to this value.MACAddressPolicy=
The policy by which the MAC address should be set. The available policies are: "persistent"MACAddress=
If the hardware has a persistent MAC address, as most hardware should, and if it is used by the kernel, nothing is done. Otherwise, a new MAC address is generated which is guaranteed to be the same on every boot for the given machine and the given device, but which is otherwise random. This feature depends on ID_NET_NAME_* properties to exist for the link. On hardware where these properties are not set, the generation of a persistent MAC address will fail."random"
If the kernel is using a random MAC address, nothing is done. Otherwise, a new address is randomly generated each time the device appears, typically at boot. Either way, the random address will have the "unicast" and "locally administered" bits set."none"
Keeps the MAC address assigned by the kernel.
The MAC address to use, if no "MACAddressPolicy=" is specified.NamePolicy=
An ordered, space-separated list of policies by which the interface name should be set. "NamePolicy" may be disabled by specifying "net.ifnames=0" on the kernel command line. Each of the policies may fail, and the first successful one is used. The name is not set directly, but is exported to udev as the property "ID_NET_NAME", which is, by default, used by a udev rule to set "NAME". If the name has already been set by userspace, no renaming is performed. The available policies are: "kernel"Name=
If the kernel claims that the name it has set for a device is predictable, then no renaming is performed."database"
The name is set based on entries in the udev's Hardware Database with the key "ID_NET_NAME_FROM_DATABASE"."onboard"
The name is set based on information given by the firmware for on-board devices, as exported by the udev property "ID_NET_NAME_ONBOARD"."slot"
The name is set based on information given by the firmware for hot-plug devices, as exported by the udev property "ID_NET_NAME_SLOT"."path"
The name is set based on the device's physical location, as exported by the udev property "ID_NET_NAME_PATH"."mac"
The name is set based on the device's persistent MAC address, as exported by the udev property "ID_NET_NAME_MAC".
The interface name to use in case all the policies specified in NamePolicy= fail, or in case NamePolicy= is missing or disabled.Note that specifying a name that the kernel might use for another interface (for example "eth0") is dangerous because the name assignment done by udev will race with the assignment done by the kernel, and only one interface may use the name. Depending on the order of operations, either udev or the kernel will win, making the naming unpredictable. It is best to use some different prefix, for example "internal0"/"external0" or "lan0"/"lan1"/"lan3".MTUBytes=
The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, G, are supported and are understood to the base of 1024.BitsPerSecond=
The speed to set for the device, the value is rounded down to the nearest Mbps. The usual suffixes K, M, G, are supported and are understood to the base of 1000.Duplex=
The duplex mode to set for the device. The accepted values are "half" and "full".AutoNegotiation=
Enables or disables automatic negotiation of transmission parameters. Autonegotiation is a procedure by which two connected ethernet devices choose common transmission parameters, such as speed, duplex mode, and flow control. Takes a boolean value. Unset by default, which means that the kernel default will be used.Note that if autonegotiation is enabled, speed and duplex settings are read-only. If autonegotation is disabled, speed and duplex settings are writable if the driver supports multiple link modes.WakeOnLan=
The Wake-on-LAN policy to set for the device. The supported values are: "phy"Defaults to "off".Port=
Wake on PHY activity."unicast"
Wake on unicast messages."multicast"
Wake on multicast messages."broadcast"
Wake on broadcast messages."arp"
Wake on ARP."magic"
Wake on receipt of a magic packet."secureon"
Enable secureon(tm) password for MagicPacket(tm)."off"
The port option is used to select the device port. The supported values are: "tp"TCPSegmentationOffload=
An Ethernet interface using Twisted-Pair cable as the medium."aui"
Attachment Unit Interface (AUI). Normally used with hubs."bnc"
An Ethernet interface using BNC connectors and co-axial cable."mii"
An Ethernet interface using a Media Independent Interface (MII)."fibre"
An Ethernet interface using Optical Fibre as the medium.
The TCP Segmentation Offload (TSO) when true enables TCP segmentation offload. Takes a boolean value. Defaults to "unset".TCP6SegmentationOffload=
The TCP6 Segmentation Offload (tx-tcp6-segmentation) when true enables TCP6 segmentation offload. Takes a boolean value. Defaults to "unset".GenericSegmentationOffload=
The Generic Segmentation Offload (GSO) when true enables generic segmentation offload. Takes a boolean value. Defaults to "unset".UDPSegmentationOffload=
The UDP Segmentation Offload (USO) when true enables UDP segmentation offload. Takes a boolean value. Defaults to "unset".GenericReceiveOffload=
The Generic Receive Offload (GRO) when true enables generic receive offload. Takes a boolean value. Defaults to "unset".LargeReceiveOffload=
The Large Receive Offload (LRO) when true enables large receive offload. Takes a boolean value. Defaults to "unset".
[Link] NamePolicy=kernel database onboard slot path MACAddressPolicy=persistent
[Match] MACAddress=00:a0:de:63:7a:e6 [Link] Name=dmz0
[Match] Path=pci-0000:00:1a.0-* [Link] Name=internet0
[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