How to get my computer Wan IP that is behind a firewall?

[123456programmer]

i couldn t find any site that tells me the way to get the wan ip that is behind a firewall...
anyone knows it? is there anyway?

 

[Griffyn]

As far as my knowledge of IP addressing goes, a website you contact will be told to return every packet to you and that your IP address is your firewall's WAN IP. The firewall then changes the incoming packet after determining it's valid so that it gets sent on correctly to your private IP address.

But, getting this packet unchanged is pretty much an impossibility because it will be invisible to your computer while it's in this state (coz it's not intended for you). There way around this is to have control of the website your computer is trying to contact. It will only ever know your firewall's WAN IP and not your own computer's. Checking it's logs, or writing a script that e-mails you the IP addresses of computers trying to contact it, for example, would tell you what you want to know.

There's a few things that can change this though. eg. If you have a NAT router and behind that (closer to your side of the LAN) is a firewall. In this scenario there's no way to ever know the firewall's WAN IP because it exists in the IP packet only while a packet is being sent between the NAT router and the firewall.