openBSD

openBSD is a security-centric, Unix-like OS. Its codebase undergoes thorough auditing to minimize vulnerabilities, culminating in secure defaults and integrated cryptographic features. The project pioneered tools like OpenSSH and PF (packet filter). openBSD uses a minimalistic approach, including only necessary packages in the base system. Additional software is available via ports or packages. While not as feature-rich for desktops as Linux distros, openBSD’s reliability and strong security make it a top choice for firewalls, routers, or critical infrastructure. It’s free under a permissive license.