For a long time I have been trying to configure port forwarding using NAT. But every attempt was futile... Finally I found that my port forwarding works just fine. But it just appears to be not working because my router doesn't support reverse NAT. In this post I will show you guys how to test whether you configure your NAT correctly or not. (Read a detailed write up by shane. Link
First make a port forwarding rule in your router say 1600. Download this little tool called simple internet tools. Install it and open port listener and select your internal IP(192.168.x.x). Then type your port number and press start listening.
Go to this site
and check whether it says port is opened. If your connection is successful you will notice it in the port listener application.
Then go to your browser and type your internet ip address. (You can find it from www.whatismyip.com) . Tnen type your port number after a colon. (184.108.40.206:1600). Your browser shows a webpage not available window. Check your port listener. If you find a connection successful message it means your router supports reverse NAT. Otherwise reverse NAT is not available.
You can also check it by an nc command like this.
nc 220.127.116.11 1600
If you didn't want to test the connection using the above site you can do it by nc from a remote ssh account. Login to your ssh account and try to connect it with nc.