OpenSSH is the free open source implementation of an SSH (Secure SHell) protocol. It replaces Telnet, FTP, rlogin, RSH, and RCP tools with secure, encrypted network connectivity tools. OpenSSH supports the SSH protocol version 1.3, 1.5, and 2. -OpenSSH is the SSH (Secure SHell) protocol to achieve a free open source. That it is using Secure, encrypted network connectivity tools instead of Telnet, FTP, rlogin, RSH and RCP tools. OpenSSH support for SSH protocol versions 1.3,1.5, and 2.