Date: Thu, 17 Aug 2000 07:14:30 -0700 (PDT) From: David Wolfskill <dhw@whistle.com> To: achilov@granch.ru, Egon.Rath@lsr-ooe.gv.at Cc: freebsd-security@FreeBSD.ORG Subject: Re: AW: deny incoming icmp Message-ID: <200008171414.HAA02662@pau-amma.whistle.com> In-Reply-To: <C96996C3D753D311A5400001FAF86B258E2A08@ntli02-003.lsr-ooe.gv.at>
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>From: Egon.Rath@lsr-ooe.gv.at >Date: Thu, 17 Aug 2000 15:48:02 +0200 >|> What type of ICMP messages uses traceroute? I'd like to mask >|> internal network structure from tracing... >Traceroute uses ICMP types 0 (Echo Reply), 8 (Echo request) and 11 (TTL >expired) to determine the route to the host. That didn't seem quite right to me, so I looked (in /usr/src/contrib/traceroute/traceroute.c); there is a rather large comment block near the beginning of the file tagged * -- Van Jacobson (van@ee.lbl.gov) * Tue Dec 20 03:50:13 PST 1988 that explains how & why the program uses high-numbered UDP datagrams for the probes. It does rely on ICMP (time exceeded; ICMP type 11) for receiving notification from a router, though. Cheers, david -- David Wolfskill dhw@whistle.com UNIX System Administrator Desk: 650/577-7158 TIE: 8/499-7158 Cell: 650/759-0823 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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