One Public Static IP with Two Email servers - Solution?

[ggilfedder]

Hi, I am switching ISP's and have a temporary sitiation where I have been given 1 public IP address for a DSL connection. On my network I have two email servers and one application server which need to receive email and be accessed from the outside. Is there anyway for me to do this without having public IP's for those three servers?

Thanks,
G

 

[bcastner]

Have them listen on different ports.

 

[manarth]

and enable port forwarding on your router (if they do not have public IPs you will need to use a router).

<marc> i wonder what will happen if i press this...[ul][li]please give feedback on what works / what doesn't[/li][li]need some help? how to get a better answer: faq581-3339[/li][/ul]

 

[ggilfedder]

Thank you, that helps me out. The only question I still have is what happens when the same type of service is running on multiple machines. For instance, each of the two email servers I have serve different domains.

So let's say my public IP is 130.102.1.1 and I open up port 110 and 25 to each of the email servers - 192.168.100.1 and 192.168.100.2 - how will it know to direct the correct mail to the correct email server?

Both of these servers are exhange servers and i have people access them using the web client. same issue - if i open port 80 on both servers, how does someone who needs 192.168.100.1 get there vs. someone who needs server 192.168.100.2?

This is where I'm getting a little confused...

 

[manarth]

as bcastner says - assign each server different ports (110 & 25 are default, but you can pick your own).
anyone connecting to WANiport110 goes to 192.168.0.1ort110, and WANiport111 to 192.168.0.2ort110

the only other way I can think of is using virtual server - if your router can support it (you need to connect using a URL - the URL determines which mail server it forwards to). You'll probably need better than a SOHO router to find a virtual server feature on a router.

<marc> i wonder what will happen if i press this...[ul][li]please give feedback on what works / what doesn't[/li][li]need some help? how to get a better answer: faq581-3339[/li][/ul]

 

[ggilfedder]

Manarth, how does email for server A know to go to port 111?Am I putting the port # after the WANip in Server A's mx record, so that when email is sent it knows to go to port 111?

And thanks for your help by the way.

 

[manarth]

you have to update each of the clients....

clients for server A connect to 20.x.x.4 (your WAN IP) on port 110
clients for server B connect to 20.x.x.4 (your WAN IP) on port 111

You've only got one public IP - so the only way a router can decide which of your servers to route to is
a) if it can examine the URL and decide which server it's destined for
b) if the user is connecting on a different port

if your clients are using outlook express: you can change the default ports by going to Tools --> Accounts --> select the &quot;Mail&quot; tab --> highlight the appropriate email account --> select properties --> select the &quot;advanced&quot; tab.

<marc> i wonder what will happen if i press this...[ul][li]please give feedback on what works / what doesn't[/li][li]need some help? how to get a better answer: faq581-3339[/li][/ul]

 

[ChrisAC]

You can't change the SMTP port for incoming mail. Any mail server sending to your domain will try to connect to the server on port 25. This you cannot change!

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
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