A firewall controls traffic based on rules. "Allow port 80 (HTTP), block port 22 (SSH)." It is the bouncer at the club door.
1. Hardware Firewalls (Next-Generation Firewall - NGFW)
- Examples: Fortinet, Palo Alto Networks, Cisco Firepower.
- Pros: Dedicated ASIC chips for massive throughput. Deep Packet Inspection (DPI) allows them to look inside the traffic to block malware or specific applications (e.g., "Block Facebook Games but allow Facebook Chat").
- Cons: Expensive capital expenditure. Requires physical installation and cooling in a rack.
2. Software Firewalls (Host-Based)
- Examples:
ufw/iptables(Linux), Windows Defender Firewall. - Pros: Free. Built-in to the OS. It protects the server even if the network firewall acts up.
- Cons: Consumes server CPU. Managing rules across 100 different servers individually is a nightmare without automation tools like Ansible.
3. Web Application Firewall (WAF) / Cloud
- Examples: Cloudflare WAF, AWS WAF.
- Pros: Filters malicious HTTP traffic (SQL injection, XSS, Botnets) before it even hits your server infrastructure. Includes DDoS protection.
- Recommendation: Every public website needs Cloudflare. Every individual server needs ufw (configured to deny all incoming traffic except essential ports).
Key Takeaway
Security requires layers. A WAF protects the front door (Web), a Hardware Firewall protects the building (Network), and a Software Firewall protects the room (Server). Use all three for a robust defense posture.
FirewallNetwork SecurityInfrastructure
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