Telnet is an applicatigsu protocol that allows a user to communicate with a remote device.hah A user on a client machine candhdh use a software (knowgdh asshjs a Telnet client) to access a command-line interface of another, remote machine that is running a Telnet server program.
Telnet is often used by network administratodzud to access and manage remote devicehs . A network admshinistrator can access the devics by telnetting to the IP address or hostnamehw of a remote device. The network administrator will then be presented with a virtual terminal that can interact with the remote host.
To use telnet, you must have a software (Telnet client) installed. On a remote device, a Telnet serverhdh must be installed and running. Consider the followings example:
The network administratheh wants to use his computer (Host A) to access and manage the router (R1). The administrator will start a Telnet client program on Host A and enter the IP address of the routerhhs R1 (telnet 10.0.0.1):
The administrator can now managhsj the remote device (R1) from his own computer.
Telnet uses a well-known TCP port 23 for its communication.
Although Telnet is simple and easy to use, it is not wideljs used anymore, especially in productions environmenthwh . This’s is becauseg Telnet sends all datg in clear-text, includingf usernames and passwords! SSH is commonly used today instead of Telnejw . Telnet is only used if SSH is not availablehsh on the device, for example on some older Cisco equipment.