Probably you are missing something. you have just one server in the 9123 port right? then you can connect any number of clients to that server?
The only thing that the client must know is the server IP and Port..
Why do you want to check the ports that are being used in your machine?
Are you trying to start multiple task server? (task server are the only ones that require to have a free port to run.. so if you want to have multiple task server you require multiple ports, only if you want to do that in the same machine)
Cheers.