[barbazfoo12]

If you want some interesting precedent, do some research on "Internet2" and the testimony of the RIAA to legislators.

Do you know what a LAN is? It is an evil invention to share copyrighted works. It must be stopped.

If you want a better understanding, read everything you can find on UDP, Ethernet, firewalls, NAT and encapsulation, in that order. I would suggest not to waste time trying to figure out "pre-packaged" peer to peer software solutions (i.e. all the different approaches people have taken, e.g., aeroFS, Kicksend or whatever). They often include far more complexity than you need to accomplish peer to peer. As such, they won't help you much to understand the basics: how connections are made.