Firewall

Firewall
Overview

A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It can operate at multiple layers of the OSI model, typically from Layer 3 (Network Layer) to Layer 7 (Application Layer).

Key Functions
  • Filters incoming and outgoing network traffic
  • Establishes a barrier between trusted internal networks and untrusted external networks
  • Applies security policies to control network access
  • Can perform stateful inspection of network traffic
  • May include additional security features like intrusion detection and prevention
OSI Model Layers

Firewalls can operate at multiple layers of the OSI model, typically from Layer 3 (Network Layer) to Layer 7 (Application Layer). This allows them to perform various types of filtering and inspection, from basic packet filtering to advanced application-level inspection.