Python connect 2 pc over internet with sockets

Hi, need to communicate 2 pc over the internet. Those are behind a NAT router, so I need a working example of a communication like this. Internet server: A python listener Pc 1: python script that ask server for ip and port of second pc Pc 2: same I'd like to make socket connections, and I don't know exactly how it works. Schema is like a typical p2p sctructure. Pc log into sever, so it opens a connection through a public port, and then I guess Pc1 is allowed to send sockets directly to the pc2 without going over the server. Like torrent does. Port 80 is desired if possible, like teamviewer. Routines have to be coded, very small and simple. 10 lines better than 20. I don't want libraries, popular scripts, etc. Code from scratch, simple and in Python. Only people capable to do this, with experience if possible, 1 or 2 days to complete it.