[NTLUG:Discuss] Mail server issues....

[Chris J Albertson]

Most likely, your DNS entries for these two servers have the public IP
addresses, which are NATed by the firewall. So, for server A to talk to server
B, the traffic must go out the firewall, where is gets converted, then sent to
the other IP, where it gets converted again and sent back into the internal ip
address. Most likely, there is no rule allowing this communication.

You could make host entries on the two servers with the internal IP address.
This would allow non-firewall communications between the two boxes.

The other thing you can do is create an internal "view" in bind 9+. This is what
I do. This way, nothing has to be changed. Your mail servers still refer to the
DNS MX and A records in the domain. They just get internal IP address resolution.
A view is just a different representation of a domain (or entries in a domain)
based upon the requesters IP address. It works really well.

-- 
Chris AlbertsonOwner - ChrisAlbertson.com  (Actually, I rent, with an option to buy)

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Quoting Douglas King <daking at dak1.net>:

 Recently, I moved a couple of mail servers behind a Smoothwall
 firewall.  Now the mail list server (Mailman) and the primary mail servers
 no longer are "talking" to each other?  Prior to the move, all the servers
 had routable IP's on them.  Now they carry 172.16.x.x IP's behind the
 firewall.
 
 Does anyone have any suggestions as to WHAT I need to do to get these
 machines talking again?
 

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