nixos/network-interfaces-systemd: improve default ethernet network ma…

…tching

Reliably match physical ethernet interfaces by using `Kind=!*` with `Type=ether`.
This will exclude veth interfaces, which have `Kind=veth`.

nixos/modules/tasks/network-interfaces-systemd.nix

@@ -45,25 +45,14 @@ let
 
  genericDhcpNetworks = initrd: mkIf cfg.useDHCP {
  networks."99-ethernet-default-dhcp" = {
- # We want to match physical ethernet interfaces as commonly
- # found on laptops, desktops and servers, to provide an
- # "out-of-the-box" setup that works for common cases. This
- # heuristic isn't perfect (it could match interfaces with
- # custom names that _happen_ to start with en or eth), but
- # should be good enough to make the common case easy and can
- # be overridden on a case-by-case basis using
- # higher-priority networks or by disabling useDHCP.
-
- # Type=ether matches veth interfaces as well, and this is
- # more likely to result in interfaces being configured to
- # use DHCP when they shouldn't.
-
- matchConfig.Name = ["en*" "eth*"];
+ matchConfig = {
+ Type = "ether";
+ Kind = "!*"; # physical interfaces have no kind
+ };
  DHCP = "yes";
  networkConfig.IPv6PrivacyExtensions = "kernel";
  };
  networks."99-wireless-client-dhcp" = {
- # Like above, but this is much more likely to be correct.
  matchConfig.WLANInterfaceType = "station";
  DHCP = "yes";
  networkConfig.IPv6PrivacyExtensions = "kernel";