Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!usc!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!mp.cs.niu.edu!rickert
From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: comp.mail.sendmail
Subject: Re: Problems with Sendmail v5.65+IDA and BIND
Message-ID: <1990Nov10.051503.21021@mp.cs.niu.edu>
Date: 10 Nov 90 05:15:03 GMT
References: <1990Nov9.090855@ap.co.umist.ac.uk>
Organization: Northern Illinois University
Lines: 45

In article <1990Nov9.090855@ap.co.umist.ac.uk> jf@ap.co.umist.ac.uk (John Forrest) writes:
>Its me again. Soyy to be such a bore, but I've spotted some potential problems
>with the 5.65+IDA source and BIND. Essentially, the domain.c source contains the
(... many deleted lines ...)
>
>As an example, the new code contains the further comments in getcanonname (after
>it has sought the resource entries for a particular name):
>
>		else if (type == T_MX)  {
>			/*
>			 * Be sure that the best MX record doesn't point
>			 * to the local machine.  If it does, some other
>			 * delivery method is assumed.
>			 */
>
>Any explanations.
>
 I first saw this in 5.61, so it is not as new as you think.  However it may
not have been in all 5.61-IDA versions.

 I believe this is Paul Pomes code.  He probably should speak for himself, and
perhaps will.  But here is how he uses it:

 In the mailer selection section (ruleset S26, called from S0) of the IDA
configuration package, this code prevents the TCP mailer from being incorrectly
selected.  The result is a search of the pathalias database to find an
alternate routing.  The way UIUC has this set up, it means that someone with
an MX record pointing to uxc.cso.uiuc.edu, and with an entry on the UUCP maps
can essentially control their own destiny.  If they modify their MX record
and/or their UUCP map entry they can control the mail routing at uxc without
having to ask for personal intervention.

 There is a drawback to this setup, however.  As you correctly point out, it
means that host names cannot be properly qualified if there is an MX record
pointing to the local host.  You can of course use DOMAINTABLE entries as
an alternative way to canonicalize addresses.  But, if you prefer to handle
MX rerouting via MAILERTABLE, you could make a good case for changing this
code.  Possibly it should depend on a #define so that it can be optionally
selected via a definition in conf.h.

-- 
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115.                                  +1-815-753-6940