IMPLEMENTASI HARDENING SERVER LINUX UNTUK MENGURANGI RISIKO SERANGAN SIBER

Ubuntu 22.04 LTS Linux servers running default configurations are highly vulnerable to cyber threats including ransomware, cryptojacking, and SSH brute force attacks due to 22+ unnecessary open ports, active root login, and weak password authentication on standard port 22. This research implements systematic hardening through Agile Development methodology comprising 4 iterative phases (assessment, implementation, testing, audit) following CIS Ubuntu Linux Benchmark v2.0.0 guidelines. Results demonstrate Lynis security score improvement from 40/100 (medium risk) to 85/100 (good) representing +112.5% enhancement, 86.4% attack surface reduction (22→3 essential ports: SSH 2222, HTTP 80, HTTPS 443), and complete elimination of critical vulnerabilities. Brute force testing using Hydra (1000 attempts) achieved 95% mitigation within