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What is Telnet? How It Works? (Explained with Examples)

Telnet is one of the foundational technologies in computer networking, often used by IT professionals to manage devices remotely. While newer protocols like SSH have overshadowed it in modern networks, Telnet remains a vital topic for understanding how network communication works.

What is Telnet?

Telnet, short for TELecommunication NETwork, is a protocol used to remotely access and manage a computer or network device over the internet or a local network.

In simple terms, Telnet allows users to:

Log into a remote system as if they were directly connected to it.
Execute commands on the remote device.

Key Characteristics of Telnet:

Works over TCP/IP protocols.
Operates in plaintext, meaning data, including passwords, is not encrypted.
Used for debugging network services, accessing servers, or managing routers/switches.

Telnet Full Form

The full form of Telnet is TELecommunication NETwork.

How Does Telnet Work?

Telnet establishes a virtual terminal connection between the user’s computer and the remote machine.

Telnet operates over TCP port 23 by default.
Once connected, the user can enter commands directly on the remote system.

Here’s how Telnet works:

Client-Server Model: The user’s computer acts as a client, while the device being accessed is the server.
Plain Text Communication: Data exchange occurs in human-readable text format.

Features of Telnet

Feature	Description
Remote Access	Enables access to devices over a network.
Command-Line Interface	Users interact via a text-based terminal.
Platform Independent	Works across different operating systems.
No Encryption	Communication is not secure (plaintext).
TCP Port 23	Uses this port by default for connections.

Telnet in Computer Networks

In the context of computer networks, Telnet is primarily used for:

Remote Device Management: Configuring routers, switches, or servers.
Testing Connectivity: Troubleshooting issues by connecting to a specific port or IP.
Legacy Systems: Accessing older systems that do not support newer protocols like SSH.

How to Use CMD Telnet?

To use Telnet from the Windows Command Prompt (cmd), follow these steps:

Step 1: Enable Telnet on Windows

Open Control Panel → Programs → Turn Windows Features On or Off.
Check the box for Telnet Client and click OK.

Step 2: Open Command Prompt

Press Win + R, type cmd, and hit Enter.

Step 3: Connect Using Telnet

Use the following syntax:

Example:

Advantages and Disadvantages of Telnet

Advantages	Disadvantages
Simple and lightweight protocol	Lacks encryption, making it insecure.
Ideal for local networks	Data, including passwords, sent as plaintext.
Supports troubleshooting and testing	Vulnerable to man-in-the-middle attacks.
Works on a wide range of platforms	Limited usage due to security concerns.

Telnet vs SSH

Aspect	Telnet	SSH (Secure Shell)
Encryption	No encryption; plaintext communication.	Encrypts all data for secure communication.
Port	Default port 23.	Default port 22.
Security	Vulnerable to attacks.	Highly secure with authentication and encryption.
Usage	Legacy systems, testing, and debugging.	Modern secure remote access.
Performance	Faster due to lack of encryption overhead.	Slightly slower due to encryption.

Telnet Examples and Use Cases

Accessing a Router:

Example command:

telnet 192.168.1.1 23

Use case: Managing a home or enterprise network router.

Testing a Mail Server:

Example command:

telnet smtp.example.com 25

Use case: Verify if the SMTP server is reachable.

Troubleshooting Ports:

Example command:

telnet example.com 80

Use case: Check if a web server is accepting HTTP connections.

FAQs

What is Telnet used for?
Telnet is used to remotely access and manage devices or test connectivity to specific network services.
What is the full form of Telnet?
TELecommunication NETwork.
Is Telnet secure?
No, Telnet sends data in plaintext, making it insecure for sensitive tasks.
What is Telnet in a computer network?
Telnet is a protocol that allows users to control remote devices using a text-based terminal interface.
What is CMD Telnet?
CMD Telnet refers to using the Telnet protocol via the Windows Command Prompt.
Can Telnet be used on modern systems?
Yes, but it is discouraged in favor of secure protocols like SSH.
What is an example of a Telnet command?
Example: telnet 192.168.1.1 23.
Which port does Telnet use?
Telnet uses TCP port 23 by default.
How do I enable Telnet on Windows?
Go to Control Panel → Programs → Turn Windows Features On or Off → Check Telnet Client.
What is the difference between Telnet and SSH?
Telnet lacks encryption, while SSH provides secure communication through encryption.

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Shivangi Vatsal

Sr. Associate Content Strategist @Unstop

I am a storyteller by nature. At Unstop, I tell stories ripe with promise and inspiration, and in life, I voice out the stories of our four-legged furry friends. Providing a prospect of a good life filled with equal opportunities to students and our pawsome buddies helps me sleep better at night. And for those rainy evenings, I turn to my colors.