Understanding Firewall Architecture for Web Servers

Firewalls act as gatekeepers between your web server and the internet, controlling traffic based on predetermined security rules. For web servers, the firewall must balance accessibility with security, allowing legitimate traffic to reach Apache or Nginx while blocking malicious attempts. Modern Linux distributions offer multiple firewall solutions, with iptables providing low-level control and UFW (Uncomplicated Firewall) offering a user-friendly interface that manages iptables rules behind the scenes.

The principle of least privilege applies strongly to firewall configuration. Web servers typically need only a few ports open: 80 for HTTP, 443 for HTTPS, and 22 for SSH administration. Every additional open port increases the attack surface, making careful firewall configuration essential. Understanding stateful versus stateless firewall rules helps create more efficient and secure configurations that maintain performance while providing protection.

Network-level attacks against web servers have evolved from simple port scans to sophisticated distributed attacks. Your firewall configuration must address various threat vectors: brute force login attempts, DDoS attacks, vulnerability scanning, and application-layer attacks. Combining firewall rules with intrusion prevention creates a dynamic defense that adapts to emerging threats while maintaining service availability for legitimate users.