How to Customize a NIC Name

Using a systemd Link File

You can create a systemd link file with Ignition configs.

For example, to name NIC with the MAC address 12:34:56:78:9a:bc to "infra", place a systemd link file at /etc/systemd/network/25-infra.link using the Butane config snippet shown below:

Example: Customize NIC via systemd Link File

variant: fcos
version: 1.5.0
storage:
  files:
    - path: /etc/systemd/network/25-infra.link
      mode: 0644
      contents:
        inline: |
          [Match]
          MACAddress=12:34:56:78:9a:bc
          [Link]
          Name=infra

Using Udev Rules

Similarly, also through Ignition configs, to name NIC with the MAC address 12:34:56:78:9a:bc to "infra", create a udev rule at /etc/udev/rules.d/80-ifname.rules using the Butane config snippet shown below:

Example: Customize NIC via Udev Rules

variant: fcos
version: 1.5.0
storage:
  files:
    - path: /etc/udev/rules.d/80-ifname.rules
      mode: 0644
      contents:
        inline: |
          SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="12:34:56:78:9a:bc", ATTR{type}=="1", NAME="infra"

Networking in the Initramfs via Kernel Arguments

If networking in the initramfs is required, the kernel argument ifname= will dynamically create a udev rule to change the name of a NIC.

Currently, unlike other parts of the networking config from the initramfs (e.g. static IPs, hostnames, etc.), these udev rules are not persisted into the real root. If the custom name needs to be applied to the real root, either a link file or udev rule must be created, as shown above. See this issue for more details.

For example, to give the NIC with the MAC address 12:34:56:78:9a:bc a name of "infra", provide a ifname=infra:12:34:56:78:9a:bc kernel argument. A udev rule would be created in the initramfs like:

# cat /etc/udev/rules.d/80-ifname.rules
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="12:34:56:78:9a:bc", ATTR{type}=="1", NAME="infra"

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