1。通過已經連線的socket檔案獲取：

  int getpeermac( int sockfd, char *buf ) { int ret =0; struct arpreq arpreq; struct sockaddr_in dstadd_in; socklen_t len = sizeof( struct sockaddr_in ); memset( &arpreq, 0, sizeof( struct arpreq )); memset( &dstadd_in, 0, sizeof( struct sockaddr_in )); if( getpeername( sockfd, (struct sockaddr*)&dstadd_in, &len ) < 0 ) err_err("getpeername()"); else { memcpy( &arpreq.arp_pa, &dstadd_in, sizeof( struct sockaddr_in )); strcpy(arpreq.arp_dev, "eth1"); arpreq.arp_pa.sa_family = AF_INET; arpreq.arp_ha.sa_family = AF_UNSPEC; if( ioctl( sockfd, SIOCGARP, &arpreq ) < 0 ) err_err("ioctl SIOCGARP"); else { unsigned char* ptr = (unsigned char *)arpreq.arp_ha.sa_data; ret = sprintf(buf, "%02x%02x%02x%02x%02x%02x", *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)); } } return ret; } 

2。 通過IP獲取：

int getpeermac_by_ip(char *ipaddr, char* buf) { int sockfd; unsigned char *ptr; struct arpreq arpreq; struct sockaddr_in *sin; struct sockaddr_storage ss; char addr[INET_ADDRSTRLEN+1]; memset(addr, 0, INET_ADDRSTRLEN+1); memset(&ss, 0, sizeof(ss)); if (argc != 2) { printf("USAGE arpg ip_addr/n"); return -1; } sockfd = socket(AF_INET, SOCK_DGRAM, 0); if (sockfd == -1) { perror("socket error"); return -1; } sin = (struct sockaddr_in *) &ss; sin->sin_family = AF_INET; if (inet_pton(AF_INET, argv[1], &(sin->sin_addr)) <= 0) { perror("inet_pton error"); return -1; } sin = (struct sockaddr_in *) &arpreq.arp_pa; memcpy(sin, &ss, sizeof(struct sockaddr_in)); strcpy(arpreq.arp_dev, "eth1"); arpreq.arp_ha.sa_family = AF_UNSPEC; if (ioctl(sockfd, SIOCGARP, &arpreq) < 0) { perror("ioctl SIOCGARP: "); return -1; } ptr = (unsigned char *)arpreq.arp_ha.sa_data; sprintf(buf,"%x:%x:%x:%x:%x:%x", *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)); return 0; }