TCP/UDP类型的套接字只能够访问传输层以及传输层以上的数据,因为当IP层把数据传递给传输层时,下层的数据包头已经被丢掉了.而原始套接字却可以访问传输层以下的数据,,所以使用raw套接字你可以实现上至应用层的数据操作,也可以实现下至链路层的数据操作(The TCP/UDP type socket can only access the transport layer and the data above the transport layer, because when the IP layer passes the data to the transport layer, the lower data Baotou has been lost. The original socket can access the data below the transport layer, so you can use the raw socket to implement the data operation to the application layer, too. Data manipulation can be implemented down to the link layer)