What determines whether new interface is treated as WAN or LAN type for routing

[laczik]

If I add a new interface, what settings determine whether it will be treated as WAN or LAN for routing?
Thanks, John

[franco]

Gateway setting for each IPv4 and IPv6 config, which is automatically implied when you set it to DHCP or a similar "upstream" connectivity mode.


Cheers,
Franco

[chemlud]

...hmmm, but if I set the interface to DHCP just because I want the DHCP server to be something else but the sense box? Some linux machine doing it for this LAN?

[franco]

I don't think this matters in real life. When your firewall is DHCP in a LAN the firewall is 99,9% of the time a router between other networks and uses the upstream gateway offered by DHCP. Otherwise you only have an endpoint device, which is fine, but it won't firewall/route.


Cheers,
Franco

[chemlud]

So if I want to use an alternative DHCP server on a LAN interface I would keep "Static IP" and use an IP from the relevant subnet, but outside the range of this alternative DHCP server?