Every system has its own security software’s so for securing your Linux, the first three steps are:
Auditing: A system scan is performed using a tool called Lynis for auditing. Every category is scanned separately and the hardening index is provided to the auditor for further steps.
Hardening: After the audit is complete, the system is hardened depending on the level of security it further needs. It is an important process based on the decision of auditor.
Compliance: The system needs to be checked almost every day for better results and also lesser threats from security point of view.