I recommend fail2ban to stop the automated attacks that are the background noise of the internet. It will set your firewall to block certain ip’s for a while, especially ports 21/22 are getting hammered with dictionary login attempts. And port 80 and 8080 for example get constantly version checked to see if you are vulnerable with an old apache, old dokuwiki etc, so don’t expose more than you need to and maybe learn about ssh tunnels and close a few.

I once installed ossim in a small network with a server and it showed me it is war out there, scripts flying everywhere.