All Archives / aussie-isp / 2002-07
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Date: Wed, 3 Jul 2002 10:27:19 +0930
From: Greg 'groggy' Lehey
To: auix
Cc: aussie-isp
Message-Id: <20020703005719.GB5827@wantadilla.lemis.com>
In-Reply-To: <20020702024859.12376.qmail@hal.netlink.com.au>
References: <20020702024859.12376.qmail@hal.netlink.com.au>
Subject: Re: [Oz-ISP] Reverse delegation (in address arpa) of mail server IP's
No followups recorded.

On Tuesday,  2 July 2002 at 12:48:59 +1000, a u i x @ n e t l i n k . c o m . a u wrote:
> Hi,
>
> We recently added some new rules for connecting mail servers,
> including one that requires that their IP address resolves to
> *some domain name* (we had to give up on enforcing a match on
> reverse delegation due to the large number of small business mail
> servers which aren't setup up in the DNS).
> The reason for adding this rule is to reduce the amount of spam
> since a fairly high percentage of spam originating IP's don't
> resolve. In this we have been quite successful and most users have
> been appreciative...
> We are getting an unexpectedly high amount of collateral damage
> with some quite high profile networks (eg. parts of aol) not having
> any reverse delegation.
>
> I'm just wondering if others on the list are using similar measures
> and what feedback/response they might have received from remote
> mail servers with this problem (so far we have not had any response -
> possibly because of the block!).

I've been doing this for about 3 years.  I take the time to scan the
error logs and report back to the domains in question, and in the
course of time the number of legit sites with broken reverse mapping
appears to have dropped.  I've just taken a look now and find the
following presumably legit sites don't have reverse mapping:

tone.orchestra.cse.unsw.EDU.AU
phoenix.welearn.com.au  (this one appears to be a Telstra problem;
                          address is 139.130.44.81)
lsrex100.racv.com.au    (I've told this one dozens of times, but
                          they're apparently too stupid to do anything
                          about it)

That's out of a total of 8,500 bounces over the last 10 days.  One
missing from there is nissan.com.au, who have also been remarkably
resistant to fixing their DNS.  It's interesting that they're all .au
domains.

Greg
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