Understanding Firewall Topologies

12 min read   Theoretical Module

Firewalls act as the primary gatekeeper for network security, filtering incoming and outgoing traffic based on defined security rules. In Rwanda's growing digital landscape, understanding how these topologies are structured is critical for national infrastructure protection.

How Firewalls Filter Traffic

Modern firewalls use a variety of methods to ensure that only authorized traffic passes through. The effectiveness of a firewall depends not just on its software, but on its physical and logical placement within the network architecture.

  • Packet Filtering: Inspecting individual packets based on IP addresses and ports.
  • Stateful Inspection: Monitoring the state of active connections to determine which network packets are allowed through.
  • Proxy Services: Acting as an intermediary between the internal network and the internet to hide internal IP addresses.
Network architecture diagram
Figure 1.1: Typical Multi-homed Firewall Architecture for Enterprise Networks.

Best Practices for Configuration

Start from a default-deny policy, segment networks into zones (internet, DMZ, internal), and review rule sets regularly to remove unused or overly permissive entries.

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