chat program behind a router

[Mark Talluto]

MC 2.4.2 b4
OS 10.1.3 on both systems


I have been working on my chat program again to refresh my memory on how 
sockets work.  BTW, anyone can have this stack if they want it.  I 
comment pretty well so it should be understandable.

It works great when everyone is on the same lan.  It also works great if 
you are not behind a personal router over the net.

Example:

computer a
He has his ip number from the isp.  He his not behind a router but is 
directly connected to the cable modem.

computer b
He he is running ipnetrouter from sustworks.com.  on a computer as his 
gateway.  He is a client on that network.

When we chat, computer b can send messages successfully to computer a, 
but computer a can not send messages back to computer b.

Is my problem with settings on the routing software or with my chat 
program?  Any insight on this would be greatly appreciated.

-Mark Talluto