Easily Test Port Forward setups using Port Listener software in Windows or Linux

You have setup a port forwarding rule on your router. You want to test whether the thing really works. One of the challenges while testing / troubleshooting port forwarding setup is often the services wont be running in your computer to test it out. In this tutorial I will explain how you can run a dummy service (port listeners) on your computer that responds to port pings.

How to run a dummy port listener service in Windows

You can run the free port listener utility to test out the port forwarding from your windows machine.

• Download the port listener software from this link
• Unzip the file
• And launch the listener.exe application present in the unzipped folder
• Enter the port number (eg.5000) that you want to test and hit "Start"
• You should see the below screen, which means the computer is now running a service on port 5000

• Now you can launch a third online port forward tester tool like canyouseeme.org to test if your port forwarding is working of not

How to run a dummy port listener service in Linux

We will use the netcat utility to run a port listener on Linux.

• First let us install netcat, by using the below command:

yum install nc

• To start the port listener as a background service, you can simply type in the below command with your port of interest

nc –l 5000 &

• That's it. If you want to validate it once, you can do so using the netstat command as shown below:

[root@Naveen ~]# netstat -anlp | grep 5000
tcp       0     0 0.0.0.0:5000               0.0.0.0:* 

You can now using any of the free online port checker services to make sure the port forwarding works!

moIrving

posted on 30 Nov 20