From: "Eric Germann" <ekgermann@cctec.com> Date: Mon, 29 Sep 2003 15:56:04 -0400 Sender: owner-nanog@merit.edu

winders does use udp instead of icmp in their tracert program, IIRC (or at least they used to). At the risk of getting my head blown off, could we say that was foresight :)

You have it backwards. Windows tracert uses ICMP while most Unix boxes use the LBNL traceroute program (or something derived from it) which uses UDP. But both rely on the return of ICMP TTL expired or unreachable messages and blocking all ICMP breaks both. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634