首先，客户端的日志服务器，网络地址转换分布为本届会议的一个端口60000 ，那么伺服器收到了用户端的地址是202.187.45.3:60000 ，这是外部的客户网络地址。同样，客户乙登入伺服器， B至吨的NAT-First of all, Client A log server, NAT A distribution for the Session of a port 60000, then the Server S received the address of Client A is 202.187.45.3:60000, which is outside of the Client A network address. Likewise, Client B Login Server S, NAT B to the distribution of the Session of the port is 40000, then the Server S received B s address is 187.34.1.56:40000. At this time, Client A and Client B and Server S can be a communication. If Client A at this time would like to direct