In the final part of our system hardening series, we tackle some of the most overlooked but impactful practices: disabling unnecessary ports and services, replacing default credentials, and removing unused software. Each of these actions reduces the number of potential entry points an attacker can exploit. Open ports often expose services that are unused or unprotected, while default usernames and passwords remain one of the most frequently exploited weaknesses. Unused or forgotten software may include outdated components or embedded credentials, introducing risk even when not actively in use. We explain how regular audits, configuration baselines, and application allowlisting can ensure a system remains minimal and secure over time. Hardening isn’t just a one-time setup—it’s an ongoing discipline that keeps attack surfaces small and defenses strong.