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Re: Strange message looping




On Tue, 10 Dec 1996, Matti Aarnio wrote:
> > kommersant.com  preference = 10, mail exchanger = smtp.kommersant.com
> > kommersant.com  preference = 20, mail exchanger = koi.smtp.online.ru
> > 
> > koi.smtp.online.ru is one of the 'alias' IP interfaces opened on
> > deimos.sovam.com.  This name *is* mentioned in the 'localnames' database
> > (and yes, it it sorted alphabetically).  Although, I am getting messages
> > like the one below (probably when the primary MX is unreachable):
> 
> 	This is why the /etc/zmailer.conf can have line line:
> 		SELFADDRESSES=mailhost.utu.fi,antares.utu.fi
> 
> 	The problem is at the MX-lookup at the SMTP-client.
> 	The SMTP-client does not know which IP-addresses are
> 	owned by the system, and there is no simple reliable
> 	way to do it...  Except by listing them manually.

This seems to have come up several times now, and I can see it becoming a
standard problem.  More and more people are running multiple IP addresses on
their systems these days.

Is there any reason why the smtp TA cannot either consult localnames or
check the interface list to automatically prevent SMTP loops?

I can see where getting a list of interface addresses could become
disgustingly OS-centric, but consulting localnames seems harmless enough.

Parenthetically, I don't understand why folks put a non-primary IP address
in their DNS as an MX RR either.  I can see doing it as a short-term fix for
a downed machine, but, in the long term, why not just use the primary IP
address for the system?

-Andy

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