使用Libpcap库捕获局域网中的IP包，要求：

打印数据包的源与目的物理地址；

打印源ＩＰ与目的ＩＰ地址；

打印出上层协议类型；

如果上层协议为TCP或UDP协议，打印目的与源端口信息；

如果上层协议为TCP或UDP协议，将数据以16进制与ASCII的两种方式同时打印出来，不可打印字符以‘.’代替；

-Libpcap library using the LAN IP packet capture, asked: Print packet source and destination physical addresses　print the source IP address of IP and purpose　print out the upper layer protocol type　If the upper layer protocol is TCP or UDP protocol, source port printing purposes information　If the upper layer protocol is TCP or UDP protocol, the 16 hex and ASCII data to the two ways to print out the same time, non-printable characters with ' .'　instead