Re: tlug: spam

[kenhrd@example.com (Ken Harada)]

Hi Steven,

The CF recipe is well documented (though in Japanese
unfortunately) at the following site:
http://www.db.cs.kobe-u.ac.jp/Lab/Rinkou/Admin/Software/CF.html

It includes SPAM/JUNK domain filtering besides relay denial.

<13673.26280.657487.543157@example.com>の記事において
turnbull@example.comさんは書きました。
>>     Ken> There are recipes available for setting sendmail.cf using CF
>>     Ken> to avoid such abuse.
>> 
>> It's easy enough to do if you simply don't do any relaying.  What do
>> you do if you need to support popmail clients from random places on
>> the Internet?  Most of them use SMTP to send the messages.
You can allow your dialup user to use your SMTP, only when they are
connecting from your IP block.  All other SMTP relay can be
denied.  

We had very extensive discussion on our local non-profit ISP,
not to allow SMTP to members who access from differnt IP block
such as when they are at work.  The conclusion was the cost to
allow such remote SMTP access is much greater than the benefit,
and such members are requested to use his nearest SMTP (usually
he should have one, at his another ISP, his office, etc).

According to our local ISP's engineer, there is already a spamming
program which "looks for" weak SMTP by testing IP address blocks
in order (he called it as "carpet bombing" type spamemr).  I don't
know other effective protection than denying relay.

I agree with you those spammers and the entities who allow such
spamming should stop it, but until then we are forced to protect
us ourselves, aren't we?

Regards,
Ken

------------------------------------------------------
Ken Harada (原田　健)
Hayama, japan
kenhrd@example.com       http://www.hayama.net/~kenhrd/
Member of:
	Internet Mutual Aid Society of Yokohama (IMASY)
	Tokyo Linux Users Group (TLUG)
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