TELNET

TELNET, an abbreviation for "Telephone Network Protocol," is a network protocol used to enable a session-based, interactive communication environment between computers over a network. It is one of the oldest network protocols used for this purpose, dating back to the early days of the Internet. TELNET provides user-oriented command-line login sessions, allowing users to remotely access and manage devices within a network.

One of the fundamental characteristics of TELNET is that it operates on a client-server model, where the user operates the client and the remote device acts as the server. Users can execute commands as if they were physically present at the remote computer, making TELNET useful for managing servers, network equipment, and other devices remotely.

However, a significant limitation of TELNET is that it does not encrypt its data, including authentication credentials. All information, including usernames and passwords, is transmitted in clear text over the network. This lack of encryption makes TELNET highly susceptible to interception and eavesdropping, posing severe security risks, especially when used over unsecured or public networks.

Due to these security concerns, the use of TELNET has largely been superseded by Secure Shell (SSH), which provides similar functionality but with encryption to secure the data transmitted between the client and the server. Despite its risks, TELNET is still used in some environments, particularly where legacy systems are in operation and the network is securely isolated from external access.