Routing call from localhost to external ip to locahost

Question

On localhost a program is calling an external IP in a specific port. I'm monitoring this via wireshark. Standard TCP connection.

What's the easiest way to route the traffic to the external IP back to localhost on a specific port?

Thanks

Answer 1

Configure your network card to have a second IP address - the external one. When the IP packet gets routed, it turns out that it needs to be delivered locally. If you listen locally to any address, you'll pick it up. Alternatively you can listen locally to the specific IP address.