Using Secure Shell (SSH) is a command method to gain remote access to your server. The security is implemented at one level using data encryption, but is augmented by server authentication, by default. Clients can compare the public key presented by the server against a list of trusted hosts, or as SSH names them, known_hosts. This is a little like using your web browser to visit HTTPS sites; occasionally, we may get warnings saying that the remote host is not trusted or cannot be identified. With SSH, instead of the browser holding the public key of the server, we have the ~/.ssh/known_hosts file to store the SSH public key of hosts we connect to.