I am very interested in at least trying to implement NAT break through for my senior project. (I am doing a networking API). It's not even a requirement of my project, just a interest of mine. I know the basics of how it works, correct me if I'm wrong: Two clients connect to a server that isn't behind a NAT and this server, knowing the IP of these two clients, tell the clients to connect to each other at the same time. Thus the "Breakthrough".
This seems not terribly easy or terribly hard to code. However, the part I'm stuck at is the testing of this. Is there a reasonable setup I can do with just one router/one NAT and my three available computers?
Thanks for any advice!
In terms of code/theory on NAT breaking, I cannot offer advice, but I can make some suggestions on setting up a test environment.
You can download a copy of m0n0wall and run it inside of a Virtual PC image (both free). This will give you a second router w/out purchasing any additional hardware. With this extra router, you can create a seperate subnet for your two clients.
Another, easier to grasp option is simply to pickup a second router, you can get a good one pretty cheap.
Then setup your existing router and server as they are now, a 192.168.1.x /24 subnet; then setup your second router (m0n0wall/hardware router) as 192.168.2.x /24 subnet, and plug the second router's "internet" port into one of the "PC" ports on your first router. Then plug both clients into the second router.
(I realize thats a bit confusing, comment if you cannot follow what I mean)