Telnet (short for Telecommunication Network) is a network protocol used to establish a remote command-line interface on another computer over a TCP/IP network. It allows users to connect to remote systems and execute commands as if they were physically present at the machine. Telnet was widely used in the early days of the internet for remote administration, troubleshooting, and accessing network devices.

However, Telnet transmits data, including login credentials, in plain text, making it highly insecure in modern networks. Due to security concerns, it has largely been replaced by Secure Shell (SSH), which provides encrypted communication. Despite this, Telnet is still used in some legacy systems, network testing, and specialized applications where security is not a primary concern.

Common Use Cases:

• Remote Access: Allows users to control networked computers and servers remotely.
• Device Configuration: Used to manage routers, switches, and other network hardware.
• Network Testing & Troubleshooting: Helps check port availability and connectivity between devices.

Key Characteristics:

• Command-Line Interface: Provides text-based interaction with remote systems.
• Unencrypted Communication: Data, including passwords, is sent in plain text.
• Port 23: By default, Telnet operates on TCP port 23.
• Obsolete for Security-Critical Applications: Largely replaced by SSH for secure remote access.