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 From:  "Klaus Stock" <ks at stock dash consulting dot com>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Limit SMTP?
 Date:  Thu, 05 Apr 2007 17:31:51 +0200
> Does anyone know of a way to limit the number of smtp connections per 
> minute?  I don't want to disable them, but I do want to discourage 
> access points from being spammer friendly.

Not really.

However, you might try somethng really dorky to reach a similar effect:

In the traffic shaper, build a pipe which you use exclusively for outgoing
SMTP traffic. Specify a delay. Anythings which now passes though this pipe
gets delayed. Most mail programs can typically accomodate a few seconds of
delay. Spam programs may or may not give up earlier when connecting to an
SMTP server. Spam programs may also use multiple concurrent connections, so
a simple delay would be ineffective in such a case. So you'll have to try to
tweak the queue size. If a mail client now fires SMTP faster than the pipe
allows, the queue should overflow and drop packets.

You will require some trial-and-error to find a setting which allows the
popular mail clients to work when normal SMTP traffic occurs.

To prevent one "SMTP power user" from bogging down all SMTP access, you
might want to create a dynamic pipe per user mask = source).

Best regards, Klaus

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