put_16aligned_be32(&arp->ar_spa, htonl(0));
memcpy(arp->ar_tha, eth_src, ETH_ADDR_LEN);
put_16aligned_be32(&arp->ar_tpa, htonl(0));
put_16aligned_be32(&arp->ar_spa, htonl(0));
memcpy(arp->ar_tha, eth_src, ETH_ADDR_LEN);
put_16aligned_be32(&arp->ar_tpa, htonl(0));