Did you start nmap as unpriviledged user? Nmap does not use ICMP echo requests when run as unpriviledged user, instead it sends a SYN packet to port 80 of the target.
If you want to be sure to use icmp ping types, use the -PE, -PP and -PM options of nmap and be sure to have the right priviledges. -- nmap wrongly reports host is blocking ping probes https://launchpad.net/bugs/91004 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
