Firewalls act as the gateway between networks, controlling data flow and enforcing security policies. They perform critical functions such as:
- Packet filtering
- Application proxying
🔐 Security Policies
Defined by organizations to govern:
- Acceptable network use
- Resources to protect
- Responses to breaches
🛡️ Types of Firewalls
Firewalls may be configured to:
- Use positive filters (allow specific traffic)
- Use negative filters (deny certain traffic)
- Apply default actions (discard or forward)
🌍 Zones of Trust
Common zones include:
- Internal Network
- Demilitarized Zone (DMZ)
- Public Internet
DMZ access is isolated to restrict exposure in the event of compromise.
✅ Strengths
- Blocks unauthorized external access
- Centralized deployment and management
- Transparent to users
⚠️ Weaknesses
- Limited protection from internal threats
- Bypassable via wireless
- Doesn't detect application-specific malware
Key Takeaway
Firewalls are essential but not foolproof. Combine with good policy, monitoring, and layered security.
