telnetd

telnetd [options]

TCP/IP command. Telnet protocol server. telnetd is invoked by the Internet server for requests to connect to the Telnet port (port 23 by default). telnetd allocates a pseudo-terminal device for a client, thereby creating a login process that has the slave side of the pseudo-terminal serving as stdin, stdout, and stderr. telnetd manipulates the master side of the pseudo-terminal by implementing the Telnet protocol and by passing characters between the remote client and the login process.

The Telnet protocol is often criticized because it uses no encryption and makes it easy for snoopers to pick up user passwords. Most sites now use ssh instead.