/************************************ author hjj date 2011-1-20 function: send an arp packet to all machine on local net modify: wenhao gcc arp.c -o arp -Wall -lnet **************************************/ #include 
     
       #include 
      
        #include 
       
         #include 
        
          #include 
         
           #define MAC_ADDR_LEN 6 #define IP_ADDR_LEN 4 int main(int argc,char **argv) {
           libnet_t *net_t = NULL; //定义libnet_t指针变量         char *dev = "eth0"; //定义设备名称         char err_buf[LIBNET_ERRBUF_SIZE];         libnet_ptag_t p_tag; //定义libnet_ptag_t变量                 unsigned char src_mac[MAC_ADDR_LEN] = {
   0x00,0x00,0xf1,0xe8,0x0e,0xc8};//发送者网卡地址         unsigned char dst_mac[MAC_ADDR_LEN] = {
   0xff,0xff,0xff,0xff,0xff,0xff};//接收者网卡地址         char *src_ip_str = "172.20.223.74"; //源主机IP地址         if(argc == 2)         {
   if(strcmp(argv[1],"-h") == 0||strcmp(argv[1],"--help") == 0)                 {
                           printf("%s","help message");                 }else                 {
                           src_ip_str = argv[1]; //赋值IP地址                 }         }         unsigned long src_ip,dst_ip = 0;         src_ip = libnet_name2addr4(net_t,src_ip_str,LIBNET_RESOLVE);//将字符串类型的ip转换为顺序网络字节流                net_t  = libnet_init(LIBNET_LINK_ADV, dev, err_buf);//初始化发送包结构               if(net_t == NULL)         {
                   printf("libnet_init error\n");                 exit(-1);         }         p_tag = libnet_build_arp(                         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这里的作用是更新目的地的arp表                         (u_int8_t *)&src_ip,//source ip addr                         (u_int8_t *)dst_mac,//dest mac addr                         (u_int8_t *)&dst_ip,//dest ip  addr                         NULL,//payload                         0,//payload length                         net_t,//libnet context                         0//0 stands to build a new one         ); if(-1 == p_tag)         {
                   printf("libnet_build_arp error");                 exit(-1);         } //以太网头部         p_tag = libnet_build_ethernet(//create ethernet header                         (u_int8_t *)dst_mac,//dest mac addr                         (u_int8_t *)src_mac,//source mac addr                         ETHERTYPE_ARP,//protocol type                         NULL,//payload                         0,//payload length                         net_t,//libnet context                         0//0 to build a new one         ); if(-1 == p_tag)         {
                   printf("libnet_build_ethernet error!\n");                 exit(-1);         } int res; if(-1 == (res = libnet_write(net_t)))         {
                   printf("libnet_write error!\n");                 exit(-1);         }         libnet_destroy(net_t); return 0; }