Handle devices with multiple interfaces properly

[pixup1]

This is an issue that appears most often when someone is using Wi-Fi and wired connections at the same time. A device with two (or more) interfaces has two (or more) MAC addresses and IPs. But it only has one browser and only sends one login request, which will only authenticate one of the interfaces.

This can be fine but if the user decides to unplug their cable thinking they can rely on Wi-Fi (or vice-versa) they can get stuck in a state where their browser thinks they are logged in and netcontrol denies them access to the network.

Then, they might try to log out and back in (unlikely), but even then they couldn't log out since netcontrol would throw an nftables error from trying to remove an item from a set in which it isn't.

I'm sure this can lead to other weird states which I haven't thought about.

I have no idea how to solve this issue (no way a website can access physical interface data, or even IPs that aren't being routed through). Maybe it would be worth looking into how other captive portals deal with this.

(Maybe don't use cookies ? idk that sounds insane)