Date: Tue, 26 Jun 2001 18:59:20 -0400 From: "Ryan Masse" <mail@max-info.net> To: "alexus" <ml@db.nexgen.com> Cc: <freebsd-security@freebsd.org> Subject: Re: disable traceroute to my host Message-ID: <003401c0fe93$a3f405e0$3200a8c0@Home> References: <006a01c0fb6b$2d64d830$9865fea9@book> <3B36267B.5B5FDBE@inforta.com> <20010625093731.A934@ringworld.oblivion.bg> <01ec01c0fdb1$6c9cada0$9865fea9@book> <20010626085804.E780@ringworld.oblivion.bg> <002701c0fe76$7530eab0$01000001@book>
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did u get my post about blackhole?
man blackhole
<snip>
In the UDP instance, enabling blackhole behaviour turns off the sending
of an ICMP port unreachable message in response to a UDP datagram which
arrives on a port where there is no socket listening. It must be noted
that this behaviour will prevent remote systems from running
traceroute(8) to your system.
<snip>
The following would enable the use of backhole of your system;
sysctl -w net.inet.tcp.blackhole=2
sysctl -w net.inet.udp.blackhole=1
The above would block *nix traceroutes using the udp method. Simply use ipfw
icmptype to block all MS attempts
Ryan
> someone else using ttl=1? that's sux.. oh well i guess its imposible to
> disable it.. cuz i dont want to block something that should work..
>
> thanks everyone
>
> ----- Original Message -----
> From: "Peter Pentchev" <roam@orbitel.bg>
> To: "alexus" <ml@db.nexgen.com>
> Cc: "Simon Rakovec" <simon@inforta.com>; <freebsd-security@freebsd.org>
> Sent: Tuesday, June 26, 2001 1:58 AM
> Subject: Re: disable traceroute to my host
>
>
> > On Mon, Jun 25, 2001 at 04:00:03PM -0400, alexus wrote:
> > > i agree this is not a solution.. looks like tty=1 is best solution so
> far
> >
> > TTL=1 is not a general solution, because it only blocks traceroutes to
> this
> > particular host, not to any machines that it is acting as a gateway for.
> >
> > Moreover, TTL=1 is not a real-world solution, because some *legitimate*
> > packets might arrive with TTL=1 (yes, there are some OS's that set too
> > low TTL's on outgoing packets, and there are some global backbone ISP's
> > which have a *lot* of routers, so it is possible that a normal packet
> > destined for your host should reach you with TTL=1).
> >
> > And just btw.. Really, why do you want to block traceroutes?
> >
> > G'luck,
> > Peter
> >
> > --
> > because I didn't think of a good beginning of it.
> >
> > > ----- Original Message -----
> > > From: "Peter Pentchev" <roam@orbitel.bg>
> > > To: "Simon Rakovec" <simon@inforta.com>
> > > Cc: <freebsd-security@freebsd.org>
> > > Sent: Monday, June 25, 2001 2:37 AM
> > > Subject: Re: disable traceroute to my host
> > >
> > >
> > > > On Sun, Jun 24, 2001 at 07:42:19PM +0200, Simon Rakovec wrote:
> > > > > Try this:
> > > > >
> > > > > ipfw add deny udp from any 32769-65535 to <your-host> 33434-33523
> > > >
> > > > As Karsten noted in a followup, this is not proper network practice.
> > > > There might be a LOT of things listening on those UDP ports,
including
> > > > ephemeral outgoing UDP connections.
> > > >
> > > > As many other people noted, this does not stop Windows traceroute,
> > > > which goes via ICMP.
> > > >
> > > > As the traceroute(8) manpage notes, this does not stop people who
> > > > know how to use the traceroute '-p port' option to select a starting
> > > > port != 32768.
> > > >
> > > > As Dag-Erling Smoerdgrav noted, in general it is impossible to
disable
> > > > a person determined to traceroute you, and in practice, there is
> > > > no need to.
> > > >
> > > > G'luck,
> > > > Peter
> > > >
> > > > PS. How was that now... one source: plagiarism, two sources:
> comparative
> > > > study, three sources: an academic thesis.. I did even better than
> that!
> > > ;)
> > > >
> > > > --
> > > > Thit sentence is not self-referential because "thit" is not a word.
> > > >
> > > > > alexus wrote:
> > > > > >
> > > > > > is it possible to disable using ipfw so people won't be able to
> > > traceroute
> > > > > > me?
> >
>
>
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