how to debug ip fowarding issue?

[Rich Bernstein]

I have a tcp app written using CVI. On a lan it works fine. Now I am trying to use it across the internet. I have a Linksys router connected to my cable modem, and then to my PC. My application is the tcp server and waits on port 15706. I have setup the Linksys to foward all of the IP messages going to port 15706 to one specific PC behind the router. My client app was also written in CVI. When the client connects to the server, I do get a connect message on the server. Next I try to send a message from the client to the server. The client sends it with a good return code, but it never shows up on the server (the callback is not even called). How can I debug this? Can I use commands of win32 directly instead of through CVI?

[RobertoBozzolo]

Have you tried pinging the client from the server and voceversa? The outut of the ping function shows you if the receiver has been reached and the time of response. To use ping, open a dos window and type (for example ping 1.2.3.4): if the receiver is active it responds and on the screen will be showed the time of response.
There is also the tracert utilit that shoud help you to detect the route your message follows in the network to reach the destination, but I never used it and I can't help you on it.
Hope this helps you a little.
Roberto