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Article: 1729
From: Anthony Howe
Date: 2007-09-23 09:01:41 -0400
Subject: Re: milter-link problems

Removal...........: milters-request@milter.info?subject=remove
More information..: http://www.milter.info/#Support
--------------------------------------------------------

Derek J. Balling wrote:
>>> Connect:localhost.localdomain           RELAY
>>> Connect:localhost                       RELAY
>> Never the above two. These should be deleted, because a spammer could
>> try to relay through your machine with:
>>
>> spammer.ip.addr.here IN PTR localhost.localdomain.
> 
> No he couldn't, because (if everything is working properly) sendmail  
> won't "trust" that PTR record because there's no corresponding A  
> record for "localhost.localdomain" pointing at the IP address.

Most resolvers will consult /etc/hosts either before or after an A 
record lookup attempt and find

127.0.0.1	localhost.localdomain localhost

thus completing the mapping reverse-forward mapping. I remember being 
told this was an issue several years ago. Maybe sendmail and the other 
MTAs detects this now, but I prefer not to take the chance.

-- 
Anthony C Howe          Skype: SirWumpus                    SnertSoft
+33 6 11 89 73 78         ICQ: 7116561          BarricadeMX & Milters
http://www.snert.com/                 
     http://www.snertsoft.com/

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