The in.telnetd program is a server which supports the DARPA telnet interactive communication protocol.

SSL telnetd replaces normal telnetd using SSL authentication and encryption. It interoperates with normal telnetd in both directions. It checks if the other side is also talking SSL, if not it falls back to normal telnet protocol.

Advantages over normal telnetd: Your passwords and the data you send will not go in cleartext over the line. Nobody can get it with tcpdump or similar tools.