icmp_seq
icmp->icmp_seq = htons(arg);
icp.icmp_seq = htons(ntransmitted);
seq = ntohs(icp.icmp_seq);
icmph->icmp_seq = htons(0);
icmpheader->icmp_seq = htons(outdata->seq);
&& icmpheader->icmp_seq == htons(seq));