Shell question

Jack Stone antennex at
Thu Oct 26 13:28:55 UTC 2006

>From: Warren Block <wblock at>
>To: Jack Stone <antennex at>
>CC: freebsd-questions at
>Subject: Re: Shell question
>Date: Wed, 25 Oct 2006 21:35:55 -0600 (MDT)
>On Wed, 25 Oct 2006, Jack Stone wrote:
>>I have managed to piece together a shell script that is able to retrieve 
>>the domains from the spams of the day and summarize those in a special 
>>file that can then be added to the sendmail's rejects in the access.db. 
>>But, first I have to eyeball the list and remove any obvious good-guy 
>>I would like to create another list of those same good guys that can be 
>>added to each day as they show up, then compare it to the above main list 
>>and delete the good guy domains before adding to the access.db.
>Greylisting will be much more effective than this approach, and is easier 
>to implement.  Combine that with sbl-xbl and maybe a few other DNSBLs, add 
>greet_pause of five or ten seconds, and you have much more effectiveness 
>with less false positives and much less maintenance. Adding clamav rounds 
>out the whole thing.  I wrote an article that covers some of this:
>-Warren Block * Rapid City, South Dakota USA

This shell script is just icing on the cake -- In addition to the DNSBLs, I 
have had all of those other filters running for years plus milter-regex in 
the front line, then greylist, then clamav, SA.

It's the SA (SpamAssassin) that provides me the list of bad-guy domains. 
It's a very short list so I can always still eyeball it and remove any 
obvious good ones. It's just sometimes I have made a mistake and let in a 
good guy, say, like one of my own domains. If I had a "good-guy list" to 
watch over my shoulder and check the bad-guy list before adding to the 
access-reject, then those would never happen again. Those bad guys are 
pretty obvious by their names.

Even if the domains are "throw-aways", I can stop a few more this way 
although I have to purge the sendmail access DB ever so often. My users 
might get 1 or 2 spams a month with my line of defenses. Takes a lot of my 
time, but worth the results. This shell would be a big help tho.

Would appreciate any more tips on how to have my daily bad-guy list checked 
against the good-guy list. Both are flat files with the domains listed in a 
single column.

Thanks guys!


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