Lynis
Free tierOpen source
Open-source security auditing tool for Linux, macOS and Unix
Open sourceFrom the lab
Bash script that audits the security of a Linux VPS
VPS Audit is a single bash script that runs graded checks on SSH, firewall, patching and intrusion signals and prints a fix beside each failure. It is for developers and admins who run their own Ubuntu or Debian servers.
The Gist, weekly