Persistent network interfaces, NixOS and USB WiFi dongles - how can I get all three to play nicely?

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1

I have a USB WiFi dongle on my PC, attached to a USB hub.
If I move either the dongle to another USB slot on the hub, or the hub to another USB port on the PC, my network breaks on reboot.

For example, when I move the dongle in the hub, it changes from wlp47s0f3u4u4 to wlp47s0f3u3u4.
When I move the hub, but leave the dongle in place, it changes from wlp47s0f3u4u4 to wlp47s0f3u4u3.

Worse, I can’t update the config to reflect the change, because I’ve got no WiFi connection to rebuild my config from, so I have to put my hub and USB dongle back in the right slots.

Can I harden my configuration.nix so that dhcpcd will ask for an IP address for the dongle interface regardless of my USB configuration?

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2

Did you consider using network manager?

3

I think networking.useDHCP still works, although it’s deprecated. See Undeprecate networking.useDHCP · Issue #75515 · NixOS/nixpkgs · GitHub.

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4

You could set useDHCP for both interfaces if you don’t want to use the deprecated setting or networkmanager. Maybe tune the timeout so it doesn’t take so long.

On a related note, why do you need an internet connection to rebuild? It should all be cached, if the DHCP setting is the only change rebuilding should work fine.

5

That might result in nixos-generate-config produces network configuration that times out when interface is removed · Issue #107908 · NixOS/nixpkgs · GitHub.

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