论坛上经常有对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。-regular forum for the discussion of P2P principle, but the discussion under discussion, Few things have real (source code). Oh, and here I will use one of their own to achieve