SSH itself is a protocol. Older NRC/RCSG supported systems use mostly version 1.5 of the protocol (version 1.2.xx of the ssh tool). All newer systems (from year 2000+) use openSSH, which supports both versions 1 and 2 of the protocol.
Version 2 of the SSH protocol is not compatible with version 1. Although it is considered more secure, and may provide more flexibility, not many public domain client and server packages are available for it.
The following commands are tools based on the SSH protocol to ensure encrypted sessions between systems.