How to use telnet command to Test Open Ports on a server from Windows Desktop

How to use telnet command to Test Open Ports on a server from Windows Desktop

Telnet is a computer protocol that was built for interacting with remote computers.

The word “Telnet” also refers to the command-line utility “telnet”, available under Windows OS and Unix-like systems, including Mac, Linux, and others. We will use the term “Telnet” mostly in the context of the telnet client software. Telnet utility allows users to test connectivity to remote machines and issue commands through the use of a keyboard. 

Enabling telnet client in Microsoft Windows operating systems

One of the most important things to remember is that Telnet is disabled by default in Window’s settings, so you need to turn it on before you can do anything.

Follow the steps below to enable telnet client on Windows 7, 8. 10:

Open Windows Start menu > Type "Control Panel" > Press Enter > "Programs and Features" > Turn Windows features on or off > Select "Telnet Client" > Press “OK"

Using Telnet to Test Open Ports

You can check if a port is open in your network by issuing the telnet command. If it is open, you will see a blank screen or connection successful result after issuing the command.

Usage

telnet [domainname or ip] [port]

where

[domainname or ip] is the domain name or IP address of the server to which you are trying to connect

[port] is the port number where the server is listening

If the port is open, you will see a blank screen or connection successful result. 

For example, to verify connection to 192.168.1.1 on port 25, issue the command:

telnet 192.168.1.1 25

If the connection succeeds, a blank screen or connection successful result will show up, meaning that the computer port is open.

A failed connection will be accompanied by an error message. It can indicate either a closed port or the fact that the indicated remote server is not listening on the provided port.

Example


Connection successful




Sometimes you may find that your own network is blocking your connection and the telnet command will show connection failed result. It’s quite common for users to be running a firewall, which blocks connection, outbound ports. A basic way to test whether your firewall is interrupting your Telnet is to disable your firewall and run a Telnet test.


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Added By:
Brian
Date Created:
10/14/2020
Last Updated:
10/14/2020