Having an SSH server can be incredibly useful; you can access a “headless” server without a monitor, get shell access to your system from anywhere in the world, transfer files without using FTP, securely tunnel VNC or web browsing, safely restart a locked-up system, and a lot more. However, improperly setting up a SSH server can leave your system vulnerable. Here’s how to install a secure SSH server (specifically OpenSSH) on Ubuntu or other Debian-based distributions.