On Sat, May 15, 2010 at 12:51 PM, Pieter Smit <mlist2010@xxxxxxxxxxx> wrote: > You would send an ICMP time exceeded (type 11) packet if you receive a > packet with a ttl=1 you will decrement it one realize it is 0 and send > the ICMP time exceeded. > > Traceroute could also use ping ICMP echo request (type 8). Or TCP SYN packets. From "man traceroute" on my Ubuntu system: -I Use ICMP ECHO for probes -T Use TCP SYN for probes Actually the "LIST OF AVAILABLE METHODS" section is quite extensive. Apparently people have been hacking on traceroute while I wasn't watching. Bill Bogstad -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html