noticed some ssh attempts to login to my server, did some research and configured fail2ban for my server which is working great, also set up mail notification as soon as user is blocked. i have noticed quite a few notification for users blocked, each with different IP. i am sure these are all automated and not like a physical user sitting there trying to brute force my server, my question is how can i make the server more secure? i have disabled the root account and there is only 1 named account on the server i am using with root privileges to maintain the server. i configured ssh keys previously but disabled this again because i am scared i will lock myself out of my server as i am the only one managing it. any suggestions would be appreciated.
I believe Lynis is probably the answer you are looking for.
It is easy to install and run. It will audit your system and provide a score out of 100 along with specific suggestions on how to better secure your operating system: