Daemon to ban hosts that cause multiple authentication errors - GitHub - fail2ban/fail2ban: Daemon to ban hosts that cause multiple authentication errors
This or similar software is basically required is you have an SSH server accessible over the internet
Don't make the mistake I did and assume that your server is too small or inconsequential to get hacked - a hacking attempt is a matter of "if" not when, but turning off password Auth and adding fail2ban will get you locked up tight
In the early days of my home server I remember looking at the logs and just watching them scroll with failed attempts. It was just a small box for messing about on with a dynamic IP. Older and wiser now.