Re: blacklist user beware

[Roy Bixler <rcb@ucp.uchicago.edu>]

On Mon, Aug 05, 2002 at 07:39:00PM +0300, Matti Aarnio wrote:
> On Mon, Aug 05, 2002 at 10:32:25AM -0500, Roy Bixler wrote:
> > This weekend when setting up Z-Mailer on a new NetBSD installation, I
> > discovered an interesting little catch.  I use the ORDB list of open
> ...
> > It turns out that, instead of the usual DNS requests of the form
> > d.c.b.a.relays.ordb.org, the SMTP server was actually requesting
> > d.c.b.a.relays.ordb.org.org.  Whoever is in charge of the org.org
> 
>    What might be in your   /etc/resolv.conf  file ?
>    Specifically if you have a "search" line(s) there ?
> 
>    My resolver has never (to my knowledge) done any such traversals,
>    but one never knows..

I did originally have a problem with my /etc/resolv.conf file, but
this was that it lacked a 'domain' line.  After I inserted one, the
'host' command at least no longer tried to resolve through the org.org
domain.  At that point, I had already put a dot at the end of my
blacklist zone in smtp-policy.src, so I didn't test smtpserver to see
if the 'domain' line in /etc/resolv.conf fixed the spurious DNS
lookups.  Also, I did not have any 'search' lines in my
/etc/resolv.conf.

But, from now on, I plan to take Arnt's very sensible advice and put a
dot at the end of all my blacklist entries.  I like the idea of less
network traffic, faster lookups and blocking out funny business like
what org.org is doing with their DNS.  (Although, to be fair, perhaps
org.org set that up in self defence and in hopes of clueing
administrators into what DNS lookups their systems are actually
generating.)

R.
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