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Date:      Tue, 19 Nov 1996 05:48:02 -0500 (EST)
From:      Thomas David Rivers <ponds!rivers@dg-rtp.dg.com>
To:        marcs@znep.com, ponds!Grizzly.COM!markd
Cc:        ponds!freebsd.org!freebsd-hackers
Subject:   Re: sendmail without DNS (was: Re: BoS: Exploit for sendmail smtpd bug (ver. 8.7-8.8.2).)
Message-ID:  <199611191048.FAA04689@lakes.water.net>

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> 
> As I mentioned before, and should have mentioned again when I moved it to
> -hackers, that still does not prevent sendmail from trying to use DNS in
> all cases.  I've tried it.  Quite a bit. 
> 
> I have tried nocanonify, nodns, a service.switch file and perhaps a few
> other things that I can't remember right now, but sendmail still tries to
> do DNS lookups.  The last time this discussion came through the conclusion
> was that the only way to change this was to recompile sendmail.  AFAIK,
> that is still the case.

 My experience exactly!  If you read the sendmail documentation; you'll
find a statement to that effect...  It was previously claimed that 
nocanonify and nodns together would cause sendmail to not use DNS; but
it didn't work for me either.

 I had to recompile sendmail to not use DNS...

 I did investigate what it took to run DNS; but it quickly degraded
into a mess for me - my machine wants to participate in 3 different
domains at the same time, and reading the DNS/BIND book on how
to do this left me without a solution...

 I'd suggest recompiling :-)

	- Dave Rivers -

> 
> On Mon, 18 Nov 1996, Mark Diekhans wrote:
> 
> > >[moved to -hackers from security.  It started with a discussion of
> > >sendmail with uucp; I stated that sendmail still tries to use DNS no
> > >matter how you configure it and you have to recompile it to make it stop.]
> > >
> > >On Mon, 18 Nov 1996, Robert Shady wrote:
> > >
> > >> > Incorrect.  It RUNS without DNS but still TRIES to use it.  If you really
> > >> > don't have IP connectivity, then difference doesn't matter because it
> > >> > still works when the lookup fails, however it still does try and the
> > >> > difference does matter if you have partial IP connectivity.  I have a
> > >> > system setup with nocanonify and all the other config file tweaks I know
> > >> > of, and it still tries to use DNS as a tcpdump shows quite clearly.  This
> > >> > system is running 8.7.5, so things may have been changed in more recent
> > >> > versions but I can't say for sure; if this has changed in more recent
> > >> > versions, please let me know.
> > >> > 
> > >> > I _think_ the define that needs to be set to 0 is NAMED_BIND, but don't
> > >> > recall for sure.  This has been gone over before on the lists.
> > 
> > I disabled the use of DNS by sendmail by adding the file /etc/service.switch
> > containing the line:
> > 
> > hosts	files
> > 
> 
> 



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