telnet, rlogin

The telnet command is used to communicate with
another host using the TELNET protocol.
It is most often used to do a remote login.


 telnet [-l user] [host [port]]

 Try:
 >telnet localhost

Use CTRL-] to quit a telnet session.

rlogin is like a minimal version of telnet.

 rlogin [-l user] [host]

These two services should never be used across a public network,
because your password can easily be read off the wire as you type it in.