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What Is Telnet?

Date First Published: 17th March 2022

Topic: Computer Networking

Subtopic: Internet Protocols

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 6/10

CONTENTS

• Security
• How To Connect To Telnet On Windows?
• History

Learn more about what Telnet is in this article.

Telnet, short for Teletype Network and sometimes further abbreviated to TN, is an application-layer protocol that provides a command-line interface for communicating with a server or a remote device. It makes use of TCP to transmit data and communicates over port 23. It is necessary for Unix commands to be used in order for Telnet to be used, which is difficult for inexperienced users who are unfamiliar with Unix commands. When users have an account on a Telnet server, HTTP and FTP allows them to request remote files from devices. Telnet is most commonly used by network administrators and developers who need to use specific applications hosted on a server or remote device. Remotely connecting to a device through the use of Telnet is referred to as Telnetting.

When logging into Telnet, a command is typed. The command contains the host and the port number. The command looks like: 'Telnet example.domain.com 23' When this command is typed, the program would ask the user for a username and password and if the credentials are correct, the user will be granted access to the remote server.

Security

Telnet itself is an insecure protocol because all messages are sent in plain text and there are no security mechanisms. Anyone that is monitoring the connection could gain access to this sensitive information since it is unencrypted. However, Telnet has been replaced by SSH (Secure Shell). SSH is much more secure than Telnet because it uses public-key encryption to encrypt messages into ciphertext. SSH works in a similar way to Telnet because it uses remote login and enables devices to communicate with a server or a remote device. As of now, it is highly recommended to use SSH as a more secure option.

Telnet has no security mechanisms. All data that is transferred to computers, including usernames and passwords are sent in plain text, meaning that anyone monitoring the connection could see this information. SSH is the recommended option for enhanced security, since it encrypts transferred data into random characters, making the transferred data unreadable by humans. It is possible that an attacker could intercept the connection and see the credentials by a 'man-in-the-middle-attack'. The main reason why Telnet has no security mechanisms is that it is one of the oldest protocols on the internet. However, it is still used now.

How To Connect To Telnet On Windows?

1. Make sure that Telnet is enabled. On Windows 10, Telnet can be enabled in Windows Features. In order to perform this action, go to Control Panel, which can be found in the ‘Windows System’ folder in the Start Menu, click on ‘Programs, not uninstall a program, click on ‘Programs and Features’, and then click on ‘Turn Windows Features on and off’. This will require administrator access. Then, find ‘Telnet Client’ in the list of Windows features and tick the box to enable Telnet. If the box is already ticked on your computer, it means that Telnet is already enabled.

2. Open Command Prompt and run it as administrator. Command Prompt is located in the ‘Windows System’ folder in the start menu, which can be opened by clicking on the Windows logo that is displayed in the bottom left corner or by clicking on the Windows logo key on the keyboard as a shortcut.

3. In Command Prompt, type 'Telnet' along with the IP address or domain name with the correct port number, such as ‘telnet 127.0.0.1 23’.
4. If the connection is successful, you should see a confirmation message about an established Telnet connection and you can then enter your username and password. If you have typed an invalid host or port, the Telnet command will return an error.

History

The first version of Telnet resulted in work from ARPANET, the predecessor to the internet. At that time, people were in need of a method of remotely accessing different computers. In response, a team of business and academic researchers created the first idea for the Telnet protocol in 1971, and the first version of Telnet was released in 1983. Telnet has been updated multiple times since then.