1.8 KiB
Renaming network interfaces
NixOS uses the udev predictable naming
scheme to assign names
to network interfaces. This means that by default cards are not given
the traditional names like eth0 or eth1, whose order can change
unpredictably across reboots. Instead, relying on physical locations and
firmware information, the scheme produces names like ens1, enp2s0,
etc.
These names are predictable but less memorable and not necessarily
stable: for example installing new hardware or changing firmware
settings can result in a name
change.
If this is undesirable, for example if you have a single ethernet card,
you can revert to the traditional scheme by setting
to false.
Assigning custom names
In case there are multiple interfaces of the same type, it's better to
assign custom names based on the device hardware address. For example,
we assign the name wan to the interface with MAC address
52:54:00:12:01:01 using a netword link unit:
systemd.network.links."10-wan" = {
matchConfig.PermanentMACAddress = "52:54:00:12:01:01";
linkConfig.Name = "wan";
};
Note that links are directly read by udev, not networkd, and will work even if networkd is disabled.
Alternatively, we can use a plain old udev rule:
services.udev.initrdRules = ''
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", \
ATTR{address}=="52:54:00:12:01:01", KERNEL=="eth*", NAME="wan"
'';
::: {.warning}
The rule must be installed in the initrd using
services.udev.initrdRules, not the usual services.udev.extraRules
option. This is to avoid race conditions with other programs controlling
the interface.
:::