Secure Shell or SSH is a network protocol that allows you to transfer data using a secured channel between network devices. The two major versions of the protocol are SSH1 or SSH-1 and SSH2 or SSH-2. Used mainly in multiuser operating systems as Linux and UNIX, SSH was developed as a replacement for Telnet and other protocols’s insecure remote access, which send information, notably the password in cleartext, allowing its discovery by traffic analysis. Encryption used by SSH intends to ensure the confidentiality and integrity of data transmitted over an insecure network such as the Internet.