icmph_du_mtu
icmph.icmph_du_mtu = htons((uint16_t)mtu);
mtu = ntohs(icmph->icmph_du_mtu);
icmph->icmph_du_mtu = htons((uint16_t)dce->dce_pmtu);
icmp.icmph_du_mtu = htons(newmtu);
ntohs(icmph->icmph_du_mtu));
icmph->icmph_du_mtu = htons(mtu);