对Sniffer软件的功能和使用作了介绍，讲述了利用工具软件解决问题的思路和一些分析方法。对IP协议，ARP协议，PPPOE协议，Radius的解码做了详解-Sniffer software on the function and use were presented about the use of tools to solve the problem of thinking and some analysis. On the IP protocol, ARP protocol, PPPOE protocol, Radius decoding done a detailed