Hi, In p->icmpv4vars and p->icmpv6vars, should integer (MTU in this case) values be stored in host or network byte order in them? On a somewhat related note, ICMPV4Vars.mtu is a uint32_t, but I think it should be a uint16_t. Also, ICMPV4_GET_MTU() doesn't work because icmpv4b isn't a member of ICMPV4Hdr.