- by x32x01 ||
Telnet (short for teletype network) is one of the oldest networking protocols that allows two-way, text-based communication via a command-line interface (CLI).
It lets you remotely access and control another device through a TCP/IP connection.
However,
Telnet lacks encryption - making it insecure compared to modern protocols like SSH. Despite that, it’s still useful for non-sensitive tasks such as:
Telnet creates a virtual terminal connection, sending commands and data together through the TCP protocol. When connecting (usually on port 23), you log in directly as a remote system user - gaining full privileges tied to those credentials.
The Telnet command is built into Windows, macOS, and Linux. But on modern Windows systems, it’s disabled by default, so let’s fix that next.
Tip: After installation, you’ll see “Microsoft Telnet Client” confirmation in CMD.
If you prefer commands, open CMD as Administrator and type:
Then restart CMD and run telnet to verify. To exit, type quit.
The basic syntax is simple:
or
Telnet remains a powerful diagnostic tool for network engineers and cybersecurity learners. While it’s not secure enough for confidential communication, it’s perfect for quick tests and troubleshooting network issues.
Pro Tip: For secure communication, always use SSH (Secure Shell) instead of Telnet when dealing with sensitive data.
It lets you remotely access and control another device through a TCP/IP connection.
However,
Telnet lacks encryption - making it insecure compared to modern protocols like SSH. Despite that, it’s still useful for non-sensitive tasks such as:
Initial network hardware configuration
Remote access within secure internal networks
Testing for open or used ports
Troubleshooting mail/web servers
Checking port forwarding
How Telnet Works
Telnet creates a virtual terminal connection, sending commands and data together through the TCP protocol. When connecting (usually on port 23), you log in directly as a remote system user - gaining full privileges tied to those credentials. The Telnet command is built into Windows, macOS, and Linux. But on modern Windows systems, it’s disabled by default, so let’s fix that next.
How to Enable Telnet on Windows 10
Option 1: Enable via Graphical Interface (GUI)
- Open Control Panel → Programs and Features.
- Click Turn Windows features on or off.
- Check
Telnet Client and press OK. - Wait for Windows to install it, then click Close.
- Open Command Prompt, type telnet, and hit Enter.
- To exit, type quit.
Tip: After installation, you’ll see “Microsoft Telnet Client” confirmation in CMD.
Option 2: Enable Using Command Prompt
If you prefer commands, open CMD as Administrator and type: Code:
pkgmgr /iu:"TelnetClient"
How to Use Telnet to Test Open Ports
The basic syntax is simple:
Code:
telnet <address> <port>
Examples:
Code:
telnet towel.blinkenlights.nl 23 Code:
telnet 127.0.0.1 80
Results Interpretation:
Error message: Port is closed or blocked.
Blank screen: Port is open and available.
Text output: Connection established successfully with the Telnet host.
Final Thoughts
Telnet remains a powerful diagnostic tool for network engineers and cybersecurity learners. While it’s not secure enough for confidential communication, it’s perfect for quick tests and troubleshooting network issues. Pro Tip: For secure communication, always use SSH (Secure Shell) instead of Telnet when dealing with sensitive data. Last edited: