linux下arp查询的源代码，可以检测网关MAC，自动探测IP冲突

arp protocol implementation in c.arp protocol retrieves mac address from ip address.

其中的源地址和目的地址是指网卡的硬件地址（也叫MAC地址），长度是48位，是在网卡出厂时固化的。可在shell中使用ifconfig命令查看，“HWaddr 00:15:F2:14:9E:3F”部分就是硬件地址。协议字段有三种值，分别对应IP、ARP、RARP。帧尾是CRC校验码。(The source address and destination address refer to the hardware address of the network card (also known as