Question about the port

小劲鸭

I am doing a TCP program, and the server system just gave me an error " connection refused!"
I am thinking maybe the port over there is not opened yet. Does anyone know what kind of tools can be used under shell or any GUI software to check whether the port (for example port 800) is opened or not on the client side?

I will appreciate your help!

Glue

用 telnet <server> <port> 就可以吧。
"connection refused" 大都因为服务器上并未开通该服务，或者被防火墙挡住了。