NAT Configuration seems impossible
I hope I'm missing the mark here, but I cannot seem to implement NAT on this router. I have been getting very frustrated by the lack of real information about how to do various things.
Here's what I want to do:
Assign a connection from an external IP address to an internal IP address for a specific service.
For example, I want all SMTP traffic aimed at IPaddress 79.9.120.12 sent to the server on address 10.1.200.12. All other incoming traffic to that external address should be firewalled by default, so connections looking for SSH or HTTP basically go into the bit bucket. (None of these addresses are real, by the way)
SMTP traffic sent to a different external address should be sent to a different internal address, as there are multiple servers handling similar traffic. My Internet connection has over a dozen IP addresses assigned to it.
From what the documentation seems to be telling me, NAT rules turn an internal address into an external address for outbound traffic, but don't seem to turn external addresses into internal addresses. Further, all traffic on a specific port at the external WAN interface will be sent to one internal server, regardless of the external address it lands on. I have three e-mail servers on my network, so I want SMTP traffic sent to the appropriate server based on the external IP address. Similarly, I have multiple web servers in my network, so I do not want all HTTP requests going to the same server.
Can anyone tell me how to accomplish these tasks? The documentation certainly doesn't seem to. I have configured several routers and firewalls in the past, and this is the strangest one I have run across.
Thanks
Norm