OpenSSH, developed as part of the
OpenBSD project, is a
free implementation of
SSH.
SSH, developed as a replacement for
rsh, implements a "
secure" method of
communication between two machines. As of version 2.0, OpenSSH supports both
SSH Protocol 1.5 (used by
ssh1) and
SSH Protocol 2.0 (used by
ssh2): something that not even the "real"
SSH produced by
SSH Communications Security can claim.
See also Blowfish and OpenSSL.