Ports on your network at home and at work are controlled by your computer’s firewall, sometimes your router, and sometimes your internet service provider.
But ports on a dedicated IP on a hosting account are opened by the host. Ports you don’t use should usually be closed by default for security reasons but if you need one opened to run a specific script or app, then your host can usually do that for you, depending on the port.
You can use online port scanners like http://www.yougetsignal.com/tools/open-ports/ to check if ports are opened, but a process needs to be running on the port for a tool like that to see that it’s opened.
For this tutorial we will be using the nc command, which is netcat, a simple Unix utility that reads and writes data across network connections, just so we will have a running process on that port.
So you can use SSH on the server and to test port 2195 for example you could run
nc -lk 2195
and while it’s running check 2195 and your dedicated IP using http://www.yougetsignal.com/tools/open-ports/.
Remember it will only show as open while the process runs so you need to check it while it’s running.