Security hardening and analysis tools.
Linux is a great operating system. Personally I use Centos and always go for the minimal installation packages. Only install the packages you need. However if you do share a server with multiple users, it may be wise to use some of the following programs and scripts to make sure that your system isn’t at risk of being compromised.
Lynis – Is a great tool that runs checks on your environment and gives you suggestions. It requires root privileges to be effective. Another option could be linux-checklist. Which works in a similar fashion.
Rkhunter – ‘RootKitHunter’ is a tool that scans your linux system for known rootkits and threats.