NAT(Network Address Translation),即网络地址转换,一定程度上解决了IPv4网络地址匮乏的问题,但也给面向P2P通信的应用程序以及协议造成通信方面的障碍。本文介绍了网络地址转换的基本原理以及其对P2P通信方式造成的冲击,简单概括目前主要的NAT穿透(NAT Traversal)技术,着重分析了UDP Hole Punching的穿透过程,最后给出一个轻量级的实现。 NAT (Network Address Translation), that is, network address translation, solves the problem of lack of IPv4 network addresses to some extent, but also causes communication obstacles for applications and protocols for P2P communication. This paper introduces the basic principle of network address translation and its impact on P2P communication. It briefly summarizes the main techniques of NAT Traversal, focuses on the penetration process of UDP Hole Punching, and finally gives a lightweight Level of achievement.