How do you know which application is occupying a port in win8

You'll need to open a Command Prompt in administrator mode. Hit Start, and then type “command” into the search box. When you see “Command Prompt” appear in the results, right-click it and choose “Run as administrator.”

At the command prompt type

netstat -ab

Select allOpen in new window

and press enter

This will give you the what port is open, what application is using it, and if the port has an active connection

Ken

Download a copy of Microsoft TCP View.  It'll provide that information.

https://docs.microsoft.com/en-us/sysinternals/downloads/tcpview

Alternately, if you prefer an interface you can try Currports
http://www.nirsoft.net/utils/cports.html

Thank you for your fast reply.
i am not sure if it is port block issue. Initially it showed the port was occupied. but now it change a little. Please see picture attached. the application is gns3, when i want to start its console, i got the error message. and it do not show 127.0.0.1 port 2002 when using netstat -ab
Capture.PNG

That's because the port isn't currently open

Are you trying to connect to it?

all you need is to is type

netstat -ab

Select allOpen in new window

nothing else.

It will list open ports and the program(s) using it

That's because the port isn't currently open

Are you trying to connect to it?

Yes, i am trying to open and connect it. how to open it?

That would depend on what the process is. In most cases you can't and generally don't need to

that means in this case, it is not port issue, right?

Thanks