The server provides a remote login facility with authentication based on privileged port numbers from trusted hosts. Ask hostname for verification. Disable keep-alive messages. If the port is not in the range 512-1023, the server aborts the connection. If the hostname cannot be determined, the dot-notation representation of the host address is used.
Normal authentication is bypassed if the address verification fails.
If automatic authentication fails, the user is prompted to log in as if on a standard terminal line. The parent of the login process manipulates the master side of the pseudo terminal, operating as an intermediary between the login process and the client instance of the rlogin program. The screen or window size of the terminal is requested from the client, and window size changes from the client are propagated to the pseudo terminal. The use of keepalive messages allows sessions to be timed out if the client crashes or becomes unreachable. All initial diagnostic messages are indicated by a leading byte with a value of 1, after which any network connections are closed.