Traceroute Anomaly

[Chuck Swiger]

Gregory Kuhn wrote:
[ ... ]
> Why can I do a traceroute using the DOS version of traceroute (tracert) 
> to any of my FreeBSD boxes, but I am not able to do so from another 
> FreeBSD box?  Furthermore, it is not just from my own boxes that I am 
> unable to do a traceroute.  Using the traceroutes listed at 
> www.traceroute.org I again am unable to trace back to my FBSD boxes.

Different traceroute programs use different protocols; in fact, the BSD 
traceroute supports:

        -P     Send  packets  of specified IP protocol. The currently supported
               protocols are: UDP, TCP, GRE and ICMP. Other protocols may  also
               be  specified  (either  by name or by number), though traceroute
               does not implement any special knowledge of  their  packet  for-
               mats. This option is useful for determining which router along a
               path may be blocking packets based on IP  protocol  number.  But
               see BUGS below.

...and if you read the rest of the manpage, it will discuss the fact that it 
is fairly common for traceroute to not show the last hop when using protocols 
other than UDP.

-- 
-Chuck