[119731] in North American Network Operators' Group
Re: Finding asymmetric path
daemon@ATHENA.MIT.EDU (William Herrin)
Sat Nov 28 17:28:55 2009
In-Reply-To: <4B11767F.4070907@kenweb.org>
Date: Sat, 28 Nov 2009 17:28:01 -0500
From: William Herrin <herrin-nanog@dirtside.com>
To: ML <ml@kenweb.org>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Sat, Nov 28, 2009 at 2:14 PM, ML <ml@kenweb.org> wrote:
> Brielle is correct. =A0The customer in question is spamming networks and =
we
> are having trouble filtering them because another provider allows them to
> source traffic however they please.
What trouble? SMTP requires two-way traffic with a static port number
that nothing else uses. If for some reason you don't want to simply
terminate their account altogether, block packets outbound to your
customer sourced from TCP port 25 but not from your SMTP smarthosts.
Seriously though, if you can prove they're spamming (regardless of
whether the packets pass through your network) save yourself some
grief and just terminate the account.
Regards,
Bill Herrin
--=20
William D. Herrin ................ herrin@dirtside.com bill@herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
