Port open verification

How to test that a port forward used for off site backup, DVR etc, actually works. Remember that if you are forwarding to a computer or server, the firewall on these devices must have the appropriate port type and port number forwarded. The port type is going to be TCP or UDP or both. If in doubt, select both and when you get the system working, drop one then the other to see precisely which one is actually needed.

On site testing;

First let’s say you are licencing a product which has its licence stored on the server on a local network. You will;

1 – Need to know the IP address of the server or the server name. In this example, let’s say the server servername is fileserver23.

2 – Need to know the port number to forward. In this example let’s say it is 22 and we don’t need to know the port type as we are only twesting to verify the port is open.

This is the test to perform;

1 – Open Powershell: click Start, type PowerShell, right-click “Windows PowerShell”, and then click “Run as administrator”.

2 – Test-NetConnection fileserver23 -Port 22.

3 – Wait for response.

Let’s say you are installing a security camera system and the manufacturer states that you must forward port 37777 to the IP address of your DVR.

First you need the IP address of the DVR. In this example let’s say it is 192.168.0.3

1 – Open Powershell: click Start, type PowerShell, right-click Windows PowerShell, and then click Run as administrator.

2 – Test-NetConnection 192.168.0.3 -Port 37777.

3 – Wait for response.

Check if there is an open port on your computer/server

From the command prompt, type in netstat -ano | find /i “22”

Off site testing;

Make sure the service is available on the local network first. Make sure the port is forwarded on the router and for goodness sake, avoid double nating it.

Ideally, the WAN connection should have a static IP so that you have a stable connection to point your remote device to. You may also have registered a domain to the IP or you may use a DYN DNS service.

Test the port forward locally first if possible. This verifies that the port number is correct ant that the device is switched on.

Make sure you have the correct WAN IP address (or DYN DNS domain name, or the predetermined domain name) and the port number to test.

1 – Open Powershell: click Start, type PowerShell, right-click Windows PowerShell, and then click Run as administrator.

2 – Test-NetConnection 123.123.123.123 -Port 37777.

3 – Wait for response.