Resolve NAT mappings

[luke-jr]

It would be useful if bandwhich could be run on routers to display the real destination IPs of NAT-routed traffic.

While it is often possible to do this by running it on the LAN interface, this would also show traffic routed between LAN devices, while the user may only want to see WAN traffic

[cyqsimon]

In order to achieve this, I guess we would have to have dynamically-updated knowledge of the firewall forwarding rules? That sounds VERY complicated considering all the different firewall implementations out there.

I could be wrong though: if I overlooked a simpler approach please feel free to point it out.