用tcpdump收集某个主机或者路由器所连接的某个物理网络上的traffic，存放到文件source.txt中。通过该程序实现对报文的简单解析，类似于Ethereal中的报文解析.Using tcpdump to collect a host or router is connected to a physical network traffic, storage of documents in source.txt. Through the program to achieve a simpl