Check Open Ports from inside and outside the network.

Hi today i will discuss about how we can check for Open ports for a device. However there are many tools available on net to check open ports. My favorite is Look@Lan. But we should must know how to check for open ports manually.

For this we have inbuilt functionality in our systems also – telnet. In Windows 7, you have to enable it. You have to follow these below steps to enable telnet ...

1. Go to Control Panel --> Program and Features

2. Click on “Turn Windows Features On or off”

3. A Pop Up window will appear.

4. Click on Telnet Client and Click Ok

This will install Telnet Client on your system.

If you are using Linux system, it must be preinstalled or you can install it according to Linux Flavor.

Suppose you are opening a port over firewall and you want to check whether it is working properly from outside to internal network or from Inside network to outer world.

Like i will check Port 443 is opened for Google or not ...

You will find the message “Escape character is '^]'.” , blank screen or message according to the Port serviced. For example if I am checking the SMTP Port you will find the Screen looks like.

So message may be vary from port to port. If the Port you are checking is blocked or disabled you will find the message like ...

Using the same procedure you can check incoming connection also to your firewall, using NATING and PATING.

I hope, this post will be helpful for you to manage your firewalls and Networks.