Date: Mon, 15 Jul 2002 08:09:15 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Wayne M Barnes <wayne@barnes1.wustl.edu> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: RPR and sendmail Message-ID: <20020715070915.GB29722@happy-idiot-talk.infracaninophi> In-Reply-To: <20020714190127.A83088@barnes1.wustl.edu> References: <20020714190127.A83088@barnes1.wustl.edu>
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On Sun, Jul 14, 2002 at 07:01:27PM -0500, Wayne M Barnes wrote:
> I have, as far as I know, a fully-registered domain. What
> is a PTR record, and why won't it resolve?
PTR records are what the DNS uses to do reverse lookups: ie to go from
the IP number to the hostname. Many processes will not only do a
forward lookup (name to IP number), but will then follow that with a
reverse lookup (IP number to name) and verify that the results contain
the original name as a defence against DNS spoofing.
> Is this something I can fix, or should I be calling my ISP?
If you're running your own DNS domain, then you should fix it. That
may include getting your ISP to delegate reverse lookups for your
netblock to you --- you can talk about RFC2317 if you want to sound
impressive... Otherwise, you should talk to your ISP and get them to
put the right data into their DNS.
> Why does it say "localhost.com"? This doesn't look right.
> Jul 14 00:28:22 klentaq sm-msp-queue[662]: g6E3wHnf000573: to=root,
> delay=01:29:58, xdelay=00:00:01, mailer=relay, pri=301424,
> relay=localhost.com. [63.231.68.113], dsn=4.7.1, stat=Deferred: 450
> 4.7.1 <root@klentaq.com>... Relaying temporarily denied. Cannot
> resolve PTR record for 64.32.219.171
That's because you're apparently sending a message to 'localhost.com',
who exist somewhere out on the net, but who are innocent third parties
in all this. Your sm-msp process is trying to pass the message to
your MTA sendmail process. To do that, it tries to speak to the SMTP
server on localhost, and because sendmail insists on looking up
everything in the DNS you need to make sure your DNS setup returns
correct data for localhost.
You should be able to lookup `localhost' and `localhost.klentaq.com'
using `dig' and get 127.0.0.1 as the address. Also you should be able
to lookup 127.0.0.1 and get back at least one of those names:
happy-idiot-talk:~:% dig localhost
[...]
;; ANSWER SECTION:
localhost. 1H IN A 127.0.0.1
;; AUTHORITY SECTION:
localhost. 1H IN NS localhost.
happy-idiot-talk:~:% dig -x 127.0.0.1
[...]
;; ANSWER SECTION:
1.0.0.127.in-addr.arpa. 1H IN PTR localhost.infracaninophile.co.uk.
1.0.0.127.in-addr.arpa. 1H IN PTR localhost.
;; AUTHORITY SECTION:
0.0.127.in-addr.arpa. 1H IN NS ns0.infracaninophile.co.uk.
The `localhost.com' thing comes from the standard domain search
behaviour to try and resolve an unqualified hostname. If your
/etc/resolv.conf contains a line equivalent to 'search com' then you
probably want to fix that too. You shouldn't put localhost.com into
your relay-domains file unless you are actually handling e-mail for
them.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
Tel: +44 1628 476614 Marlow
Fax: +44 0870 0522645 Bucks., SL7 1TH UK
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