Current Peer-to-Peer (P2P) systems were developed and implemented as a result of a direct requirement/demand without an overall functional architecture. This makes the performance of the resulting systems far from optimal because other aspects

这是基于TCP协议的NAT穿透技术在P2P中的研究与实现的pdf文件，包括原理，穿透过程，很有参考价值-This is the penetration process of TCP NAT traversal in P2P pdf file, including the principle of great reference value! !

这里面有3篇关于tcp如何打洞建立p2p连接的文章，介绍了原理，也有实例的代码。-There are three articles to establish p2p connection on tcp how holes, introduced the principle, there are also instances of code.