How to get *internet* IP?

Question

Imagine a situation, I have PC with two lan cards, one is connected to internet another is connected to local network, how can I detect IP which is connected to internet wi

Answer 1

For a quick hack (that will certainly become broken with elaborate LAN configurations or IPv6), get a list of all IPs the current machine has, and strip out all IP:s that match any of the following:

10.*
127.*          // <- Kudos to Brian for spotting the mistake
172.[16-31].*
192.168.*