Server hardening is the process of tightening a server’s configuration to reduce attack opportunities. It means removing unnecessary services, disabling risky defaults, enforcing strong authentication, limiting privileges, and keeping software patched. The goal is simple: give an attacker fewer paths to reach sensitive functions or take control.
In cyber security, hardening matters because many compromises begin with exposed management features or weak settings. For example, disabling direct SSH root login is a hardening step: it prevents attackers from going straight to the most powerful account and forces them to face extra controls such as named accounts, key-based authentication, and privilege elevation. Good hardening also helps defenders by making unauthorized access easier to detect and less damaging if it succeeds. It should be tested carefully, because a misconfigured control can lock out legitimate administrators.