Add Layers of Security to my Server, Harden it, start with SSH -- 2

My virtual dedicated server already runs Cloudflare, CSF, Fail2Ban, Nginx and MariaDB, yet I still feel the security net could be tighter. I need someone who can jump in today and begin by locking down my server, adding layers of protection and

Phase 1 – SSH hardening
• Replace password logins with key-based authentication that requires a strong passphrase on each login.
* turn off auto login on ssh key based authentication
* have users with less privileges than some users. i got 2 accounts for that.
* allow 1 user account to use sudo or sudo i or su root and then root Password
* i want root Password to be separate from users Password.

Phase 2 – Additional layers (your expertise)
Once SSH is airtight, I want you to review the entire stack and recommend the next most effective defences—whether that is an intrusion-detection system, a web-application firewall, automated server-hardening scripts, or another measure you trust. We will prioritise quick-win protections first, then schedule deeper changes if needed.

Acceptance
• SSH login succeeds only with approved keys and passphrase; root does not accept passwords.
• Clear, step-by-step notes left in /root/HARDENING_README with every change you make and how to revert it.
• A brief report summarising recommended follow-ups for layers beyond SSH.

I can provide immediate console access and will stay available on chat for quick testing or restarts. If you thrive on fast turnarounds and know your way around Linux security tooling, let’s get this locked down today.