Telnet

1. The user invokes the telnet client process, usually by name from the command line, eg:

   telnet ironbark
   

   Once running, the client process then establishes a TCP connection to the desired telnet server, which is "waiting for connections" at the well-known port 23 -- note that we are again ignoring the question of how the name "ironbark" gets translated to a network address, see later.
    
   
2. In the case of Unix, the telnet server connects the incoming connection to a variation of the standard "login" process on the server host. This may work differently on other systems.
    
   
3. The user's keystrokes are transmitted to the remote server, and output is displayed on the user's screen. Thus, initially the user can "log in", and once authenticated (using a username/password pair) has a normal shell, or command line interface, on the remote host.