Firewall Types and Implementations

A firewall is a device that monitors and controls network traffic. It is generally placed between an enterprise's internal network and the internet to protect the organization's systems and infrastructure.

A security manager should understand the following types of firewalls, as well as how they should be structured for better protection of information assets:

Figure 8.1: Types of firewalls

Types of Firewalls

The following are the basic characteristics of these different types of firewalls.

Packet filtering Router

A packet filtering router is the simplest, and the standard, version of a firewall. It tracks the IP addresses and port numbers of both the destination and source and acts (either to allow or deny the connection) as per the defined rules. A packet filtering router functions at the network layer of the Open Systems Interconnection (OSI) model.

Stateful Inspection

A stateful inspection firewall...