Telnet is the protocol that allows a user to communicate with a remote device. It is used mostly by network administrators to remotely access and manage devices. Administrator can access the device by telnetting to the IP address or hostname of a remote device.
To use telnet, a software (Telnet client) must be installed. On a remote device, a Telnet server must be installed and running. Telnet uses TCP port 23. Telnet was designed to work within a private network and not across a public network where threats can appear
SSH is the protocol used to remotely access and manage a device. SSH uses encryption, which means that all data transmitted over a network is secure from eavesdropping. Like Telnet, a user accessing a remote device must have an SSH client installed. On a remote device, an SSH server must be installed and running. SSH uses TCP port 22 by default.
SSH offers security mechanisms that protect the users against anyone with malicious intent while Telnet has no security measures. The security issues of Telnet required a people to use SSH in order to protect network.
Enlisted below are the key similarities between SSH and Telnet –
- Both are network protocols which allow users to login to remote systems and execute commands on them.
- Access to command line of a remote host is similar in both protocols
- Both use TCP protocol
- Both work in Client-Server Model
- Both are terminal based protocols
Below table elaborates the difference between both the protocols –