dns nat service.switch sendmail

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From - Mon Jul 31 07:30:24 2000
Path: news.randori.com!news-feeder2.wcg.net!WCG!attbtf.ip.att.net!news.idt.net!newsfeed.mathworks.com!cyclone.swbell.net!nnrp1.sbc.net.POSTED!not-for-mail
Message-ID: <398213A8.136E0C51@worldnet.att.net> 
From: Steve Fabac <smfabac@worldnet.att.net>
Organization: S.M. Fabac & Associates
X-Mailer: Mozilla 4.08 [en]C-WNS2.5  (Win16; U)
MIME-Version: 1.0
Newsgroups: comp.unix.sco.misc
Subject: Re: Primary DNS server, NAT, and sendmail configuration problems.
References: <39737C7F.9A0DDF23@worldnet.att.net> <3974359C.453E69EE@landis.nl> <3974DFBD.9D494FAD@worldnet.att.net> <3975AD1A.65FFB2BA@landis.nl> <3980D30F.1978C951@worldnet.att.net> 
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 80
Date: Sat, 29 Jul 2000 00:13:44 +0100
NNTP-Posting-Host: 208.190.203.168
X-Complaints-To: abuse@swbell.net
X-Trace: nnrp1.sbc.net 964847637 208.190.203.168 (Sat, 29 Jul 2000 00:13:57 CDT)
NNTP-Posting-Date: Sat, 29 Jul 2000 00:13:57 CDT
Xref: news.randori.com comp.unix.sco.misc:63729
X-Mozilla-Status: 8010
X-Mozilla-Status2: 00000000

Steve Fabac wrote:
> 
> Tony Earnshaw wrote:
> >
> > Steve Fabac wrote:
> >
> > > Good information but still doesn't help me duplicate your configuration.

Snip

> 
> Since my last post, the IDSL line was brought on-line and
> I have removed the named.conf file in /etc and killed named.
> I have installed the /etc/resolv.conf that points to the ISP's
> DNS server and have had the ISP hosting the client's web site
> to update their DNS records so that company.com points to the
> public IP address of the IDSL router.
> 
> Browsing the internet works ok and e-mail to some sites works,
> but e-mail to att.net and swbell.net fails.
> 
> The odd thing is that if I telnet to port 25 on the mail host
> for swbell (returned by dig MX swbell.net) I can interactively
> enter HELO, MAIL FROM:, and RCPT TO: using the account names
> on company.com and my mail address at swbell.net and the mail
> is accepted and delivered to target address. If I try "telnet
> swbell.net 25" I get connected to a web server and not the mail
> host(s) machine.
> 
> If I use mail -s "testing" smfabac@swbell.net, the message
> hangs up in /usr/spool/mqueue and is returned to me as undeliverable.
> 
> As I pointed out in my first posting, I have two clients on same
> ISP with IDSL connections. Both running SCO 5.0.5 Enterprise and
> both setup the same way (/etc/resolv.conf, sendmail.cf, etc.
> modified with the appropriate company information).
> 
> One client can send mail without problems to att.net and swbell.net.
> the other client (company.com) can not.
> 
> The only difference between the two sites, is the bad site was setup
> with a primary dns server (now disabled) while the IDSL line was
> inoperable. The other company's sendmail.cf and resolve.conf was setup
> after the IDSL line was working and DNS was never attempted on their
> system.
> 
> I am pulling my hair over this one. It looks like sendmail at the
> "bad" site is not correctly getting the MX record for swbell.net
> or att.net.  Sending e-mail addressed to smfabac@mta1.rcsntx.swbell.net
> works from the "bad" site, but smfabac@swbell.net does not.
> 
> Any suggestions?
> 
>                                      Steve Fabac
>                                       S.M. Fabac & Associates

Found it!!!!

This system was setup with the "service.switch" modification in 
SCO TA107669 created on 07 April 1997 , last updated on 18 January 2000 

This modification was applied to the system some months back to try
to resolve the apparent problem with SCO 5.0.5 with 3Com 3C905 NIC
and Digi MPI 3.0. 

When I began working on this client to reconfigure the system for
internet mail. I edited the sendmail.cf file and changed the line
OI-DNSRCH back to just OI.  I then removed the lines in sendmail.cf
that refer to /etc/service.switch.

BUT I DID NOT remove /etc/service.switch. Even without the line in
sendmail.cf that referred to /etc/service.switch, SCO's version 8.8.8
will still find the /etc/service.switch file and then it failed
to resolve the MX records for att.net and swbell.net

I hope this post helps some one else fighting the same problem. 

                                     Steve Fabac
                                      S.M. Fabac & Associates
                                       816/765-1670

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