How do you test if a firewall port is open if there are no services listening on the port? What about UDP Ports?

This came as a question from one of my friend. In order to confirm that a firewall port is open after a change request is completed but there is no active services on the target server listening on that port to confirm if its opened and what about the UDP Ports?

Here is a way on how you can test it. First you will need 2 application

1) Port Listener

2) PortQryUI

Test Case : Test if Port 55050 is open

As you can see 55050 is not listening. So download Port Listener extract the file and launch it

Select the Protocol and the Port to Open and Click Start
For this we will use UDP 55050

You would see a screen something like the one below.

And now you would have a active port for testing

Test Case 2 : Testing UDP

Download PortQryUI, launch on the source server. Let's use the same port to test
(UDP 55050 on the listening server)

Enter the lisening server IP address or it's FQDN, Ports and Protocol, Click Query

If port is not opened the results will look like this

If port is opened, the results will look like this

That's all for now! Happy Port Testing!