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Article: 1730
From: Jim Hermann - UUN Hostmaster
Date: 2007-09-23 09:21:49 -0400
Subject: Re: milter-link problems

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

Derek J. Balling wrote:
> On Sep 23, 2007, at 8:22 AM, Anthony Howe wrote:
> >> 2.) For testing reasons I habe on a test machine the following  
> >> simple =
> >> access.db
> >>
> >> 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.

Here's how my Sendmail 8.13.7 responds with the PTR record is localhost:

Sep 23 08:02:49 host sm-acceptingconnections[16916]: l8ND2OZu016916:
from=<dwscubaservicem@scubaservice.com>, size=0, class=0, nrcpts=0,
proto=ESMTP, daemon=MTA, relay=localhost [] (may be forged)

Sendmail appears to accept the invalid PTR record.  Another example of
invalid PTR record:

Sep 23 07:51:09 host sm-acceptingconnections[12739]: l8NCp22N012739:
from=<Amos@rogers.blackberry.net>, size=0, class=0, nrcpts=0, proto=SMTP,
daemon=MTA, relay=domain.not.configured [] (may be forged)

In both cases, Sendmail bounced the message for other reasons, not the lack
of a valid domain name in the PTR.

Jim Hermann <hostmaster@UUism.net>
UUism Networks <http://www.UUism.net>
Ministering to the Needs of Online UUs
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