Nat on Cisco serial interface

[stevem001]

Here's my scenario:

A 17xx router with serial and ethernet interfaces.
The serial interface has a /30 allocated from the ISP.
The ethernet is using private addressing (RFC 1913) as are the hosts and servers on the internal network.
Nat with overloading is applied against the serial interface of the router and all hosts/servers can access the Internet.

The company's web site is hosted offsite and their mail server POPs the mail from the ISP down to their local server which is why overload works well today. Now they want mail sent directly to their local mail server and they want to host their web site on a local server.

Question: How can the Nat be changed to support web surfing and mail delivery. As presently configured the overload will not work and there are no available IPs in the /30 to establish static Nat mappings.

Any pointers would be greatly appreciated.

- Stevem001 -

 

[dx1]

I belive port forwarding would work. Point your DNS record for MX and

http://WWW to

the outside address and have that forward to the inside server.
Personally, I would get more addresses from the ISP and create the static mappings.

 

[stevem001]

Thanks. I think I see what you're pointing .

I need to change my nat entry from overloading to static and insert entries for tcp/udp ports (25 - SMTP, 53 - DNS, 80 -

http://WWW).

Does an inside source translation suffice for each protocol and port pair? It would appear so. Anything else to consider beside modification to the ACLs?

thanks

-stevem001-

 

[BuckWeet]

You don't have to change the overloading, this will still working.. But yet you need to do a command like this:

"ip nat inside source static tcp 192.168.1.10 3389 interface FastEthernet0/1 3389"


192.168.1.10 being your internal ip, tcp being the protocol, and 3389 being the port number, fastethernet 0/1 being the port with the global IP.

BuckWeet

 

[stevem001]

Thanks to all.
I've implemented the recommendations and all is working fine.

-Stevem001-