Linux Firewall Configuration: Opening Ports and Security Policies

Linux firewalls are the core of server security, filtering traffic to prevent intrusions. Major tools include: firewalld (recommended for beginners, zone-based management such as public/trusted), iptables (underlying advanced), and ufw (Ubuntu-specific). Key firewalld configurations: Check status (systemctl), open temporary/permanent ports (e.g., 80), view rules (--list-ports). Note testing rules, backing up configurations, and avoiding tool conflicts. Mastering basic configurations reduces risks; advanced strategies (e.g., rate-limiting connections) can be extended for enhanced security.