What should be done to harden the operating system?

Hardening of the OS is the act of configuring an OS securely, updating it, creating rules and policies to help govern the system in a secure manner, and removing unnecessary applications and services. This is done to minimize a computer OS’s exposure to threats and to mitigate possible risk.

What does system hardening mean?

System Hardening is the process of securing a system’s configuration and settings to reduce IT vulnerability and the possibility of being compromised. This can be done by reducing the attack surface and attack vectors which attackers continuously try to exploit for purpose of malicious activity.