Date: Mon, 25 Jun 2001 15:52:53 -0400 From: "alexus" <ml@db.nexgen.com> To: "Peter Pentchev" <roam@orbitel.bg>, "Fernando Gleiser" <fgleiser@cactus.fi.uba.ar> Cc: <freebsd-security@FreeBSD.ORG> Subject: Re: disable traceroute to my host Message-ID: <018601c0fdb0$6c00b130$9865fea9@book> References: <006a01c0fb6b$2d64d830$9865fea9@book> <20010622221554.K5703-100000@cactus.fi.uba.ar> <20010623143419.A29940@ringworld.oblivion.bg>
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i can't just block whole icmp .. or udp.. i just can't.. i only wanted to block certain range,type whatever was that just for traceroute .. but i was thinking .. and yes I won't gain much (infact nothing) so ... the max thing i'll do is disable ttl=1.. this should cover the trick.. ----- Original Message ----- From: "Peter Pentchev" <roam@orbitel.bg> To: "Fernando Gleiser" <fgleiser@cactus.fi.uba.ar> Cc: "alexus" <ml@db.nexgen.com>; <freebsd-security@FreeBSD.ORG> Sent: Saturday, June 23, 2001 7:34 AM Subject: Re: disable traceroute to my host > On Fri, Jun 22, 2001 at 10:23:30PM -0300, Fernando Gleiser wrote: > > On Fri, 22 Jun 2001, alexus wrote: > > > > > is it possible to disable using ipfw so people won't be able to traceroute > > > me? > > > > I don't know if it is posible with ipfw, but with ip filter you can add > > a rule to block any packets with ttl=1: > > > > block in log quick on xl0 ttl 1 proto ip all > > > > That will stop windows traceroute (icmp based) as well as unix traceroute > > (udp based). > > > > Unix traceroute uses udp packets with destination port > 33434, but this can > > be changed. As far as I know, the only way to stop traceroute is to drop > > any packet with ttl=1. This might block legitimate trafic, but I haven't > > seen any packet in the wild with ttl=1 wich was not a traceroute. > > This shall only stop traceroutes destined for this particular machine. > If you tried this on a firewall/gateway machine, it would block the response > from the gateway itself, but the internal machines would still respond. > > The response from Igor Podlesny in the thread contains a much more > effective approach, which might block a bit too much, but it would > certainly block traceroutes. > > Oh and BTW, blocking all packets with ttl=1 could block some legitimate > packets that have simply gone down the long and winding road, and stopped > at too many auberges to rest along the way :) > > G'luck, > Peter > > -- > If wishes were fishes, the antecedent of this conditional would be true. > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-security" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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