Final answer:
Firewalls are commonly used at the WAN, LAN, and host layer in a security design as a barrier between trusted and untrusted networks and control network traffic based on security rules.
Step-by-step explanation:
Firewalls
Firewalls are commonly used at the WAN, LAN, and host layer in a security design. They act as a barrier between a trusted internal network and an untrusted external network, controlling incoming and outgoing network traffic based on predetermined security rules. Firewalls prevent unauthorized access and protect against network attacks, making them an essential part of layered security controls.
Example:
- WAN layer: A network firewall in the form of a hardware appliance is placed at the perimeter between a company's internal network and the public Internet.
- LAN layer: A software firewall is installed on each workstation within a network to filter traffic between the workstation and the LAN.
- Host layer: Built-in host-based firewalls on individual devices, such as laptops or servers, help protect them against unauthorized access.