I recently had to help somebody with a Windows 10 based application which offered a “connection” facility (i.e. enter your computer’s IP address and port and the 3rd party system would connect to it), but the application failed to say which port(s) it had open.
Whilst there are a number of ways to view open ports – such as Microsoft’s Sysinternal’s TCPView and NirSoft’s CurrPorts – I wanted to suggest a way which neither required an additional piece of software to be installed and didn’t require administrator access.
Here are the steps to find out what ports application “AppName” has open: