From: Bernhard Reiter (bernhardintevation.de)
Date: Mon Jan 07 2008 - 07:51:59 CST

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There is a method proposed to reduce spam:
Simulate a tar pit so that spammers will give up,
by stuttering the first n bytes of an SMTP connection.

I have just read an article by Thomas Eggendorfer
in the German Linuxmagazin (02/08 pages 74ff.).
Eggendorfer published about this a lot, see
http://www.unibw.de/inf3/institut/personen/wimis/eggendorfer/eggendorfer_publ .

I have not yet found an English paper which would be openly accessible,
there is a slide show with the rough concept (check pages 12ff):
http://lxxi.org/files/spamcon07/eggendorfer-smtp_tar_pit_simulator.pdf
(MIT Spam Conference 2007).

The Linuxmagazin article contains pseudo code for sendmail,
has somebody tried doing this with postfix?

Eggendorfer claims that 80% of spammers disconnected if a maximum of 120 Bytes
was stuttered with a maximum of 1.5 seconds pause (per Byte I assume). He
puts forward the argument that early tar pit detection will be made harder
with intelligent stuttering, thus raising costs for spammers while imposing
only small limits on legitimate users.

Having a stuttering postfix seems attractive. ;)

Bernhard

--
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Geschäftsführer Frank Koormann, Bernhard Reiter, Dr. Jan-Oliver Wagner

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