NAT issues using Route-Map

[dtappen]

I have an application using Route-map with NAT. The problem I am running into is that when an outbound packet is sent, the router creates a dynamic fully extended translation entry (including source ip/port and dest ip/port). Due to specifics of the outside host, it responds on a different port back to the inside host. As I understand it, eventhough the response packet is directed at the NAT'd inside global IP, the port is different, so no translation exists and thusly the packet is dropped. Am I correct in this assessment? Is there a solution for this problem?

 

[cisconooblet]

You are correct in that assessment.


Not sure of a solution. I'm sure burt or unc will have an answer.

CCNA
Network +

 

[dtappen]

Figured it out I think.

Added static NAT entry for the "other" port.

syntax:

ip nat inside source static udp inside_local_ip port inside_global_ip port

 

[cisconooblet]

Wait ....maybe I'm not reading your question right.

Why would your destination host (server or whatever) respond on a port other than the one it received the packet? If your inside local host sends info to a web server, and you have a router natting out the traffic to the internet...the web server will receive the packet on port 80 and then send its response FROM (source) port 80 back to the sender.

CCNA
Network +

 

[dtappen]

Because the developer of the destination host had their own ideas as to what made "sense". To shed some light, this is not really a client/server application, but more two hosts communicating various types of data over IP.