经常有对P2P原理的讨论，但是讨论归讨论，很少有实质的东西产生（源代码）。呵呵，在这里我就用自己实现的一个源代码来说明UDP穿越NAT的原理。-often principle of peer-to-peer discussions, but the discussions under discussion, with little substantive things have (source code). Oh, I am here on their own to achieve one of the source code to illustrate the UDP Through NAT principle.