One can do a basic test of TCP using Putty. UDP is another matter, one must have a server process and a sender. I found the simple sender and server written in Powershell here:
cloudbrothers.info/en/test-udp-connection-powershell/
to be excellent. In addition, if you want to know the identity of the process listening on a port, run this:
Get-Process -Id (Get-NetUDPEndpoint -LocalPort YourPortNumberHere).OwningProcess