If you would like to test ports on your computer, use the Windows command prompt and the CMD command netstat -ano. Windows will show you all currently existing network connections via open ports or open, listening ports that are currently not establishing a connection. The command also shows you the PID number, i.e., the process ID for the process that is currently using a port or is listening via a port.
How to use netstat -ano to test ports:
Step 1: Open the command prompt as administrator by pressing the Windows shortcut [Windows] + [R], entering “cmd”, and pressing [Ctrl] + [Alt ] + [Enter] to confirm.
Step 2: Enter the cmd command netstat -ano to view current network connections, IPs, and associated process IDs. Under Status, you will see entries such as “ESTABLISHED” if there is a connection to a service, or “LISTENING” if a port is open, but no connection has been established.