Björn Grönvall was the original person to remind our community that very old versions of the real ssh had a free licence. This is his own implementation, based on the old Tatu code. OpenSSH was based on an early version of OSSH, but OpenSSH added SSH2 and extended the SSH1 protocol support.
"ssh uses cryptographic techniques to enhance the security of everyday distributed computing tasks such as file transfers, remote logins and remote command execution. It's intended as a (more) secure alternative to the likes of telnet, ftp, rsh, rlogin and rexec - and one which requires much less effort to set up than Kerberos or IPSEC currently do."