Exchange internet mail connection through router

[gghusn]

How does one connect Exchange server to the internet through a NAT router like the Acsend Pipeline 50? Microsoft says it can only be outgoing, (Q193863) but that doesn't make sense - a periodic connection to the ISP is similar but the RAS can't see the router. Any help would be appreciated.

 

[Warcorp]

The problem is that outbound for NAT is easy since the outbound translated address is real even though the inside is not. Since SMTP is a true point-to-point system (meaning smtp mailers need to be able to see the end ip address of the smtp acceptor)you would need something on the router to accept the inbound SMTP that is a legal address since the ip of the actual accepting smtp system is not legal. What you may be thinking of is an ESMTP system where the mail destination is actually at an isp and as the connection is made the esmtp mailer sends it down. This works since point-to-point, ip addresses are all legal since the destination is at the ISP and not behind your NAT. The option here is to check and see if the router will do smtp proxy where the end distination is the legal side of the NAT. The proxy then re-wraps the packets with new IP detinations and sends it to the internal smtp server.

 

[choice]

To refer to your networking problem and avoid the exchange issue the following may help.<br>
I am not sure of the config on an Ascend Pipeline router but I do know that on a CISCO you can map a port on the router to an internal IP address. This is the format in Cisco IOS 11.3<br>
"ip nat inside source static tcp 192.168.0.253 25 206.186.151.5 25 extendable no-alias"<br>
Where 206.186.151.5 is a valid IP and 192.168.0.253 is not.<br>
This is assuming you always get the same address from your ISP for the router.<br>
This should allow the ISP smtp machine to communicate with the internal server since it will hit a valid IP and port which the router refers to your internal server.<br>
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