George Perkins said:
> Traceroute does not use pings, which are ICMP packets (ECHO_REQUEST sent,
> ECHO_RESPONSE returned) by default, it uses UDP packets (on many systems
> one can choose, however, to alter the default and send the ICMP "ECHO"
> family packets instead). What I forgot in my initial suggestion was that
> the responses traceroute listens for are ICMP TIME_EXCEEDED and/or
> UNREACHABLE packets (depending on which is appropriate), so even though
> the UDP packets it's sending out may get through an ICMP block, the ICMP
> packets it's listening for may not.
>
> There are network utilities available which use repeated TCP or UDP
> connection attempts in order to simulate pings in an environment where
> ICMP is not useful/useable. Many hacker toolkits make use of them
> (though actual hackers tend to use other features beyond the simple
> "can I get through to system A?" functionality).
Actually, Windows traceroute ("tracert") DOES use ICMP ECHO packets.
If anyone has a lead on a good ping/traceroute for Windows that uses
UDP (or TCP or either), can you let us know?
Doug
Doug Nelson [log in to unmask]
Network Manager Ph: (517) 353-2980
Computer Laboratory http://www.msu.edu/~nelson/
Michigan State University
