In this article we will show you how to secure your Debian virtual server and protect your self from any unauthorized access. We are going to learn how create and use SSH key pair authentication to log in to your server via SSH and some basic firewall rules implementation and protection.
Another thing that you may be interested in is the automatic blocking mechanism called Fail2Ban.
The first thing that you will need to know is that in this tutorial you can use and work as the ROOT user, however logging in to your server as the ROOT user is pretty risky thing if you do not know what are you doing. As ROOT you can do anything you want and execute any command you want and that even includes a command that can accidentally break your system and delete anything from it. That is why in this tutorial we will create another system user account and we will be using that account at all times. You will also need to know that even with the new created system user account you will still be able to execute superuser commands using sudo.