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TICSA TruSecure™ ICSA Certified Security Associate Exam TU0-001 by Shawn Porter, Debra Littlejohn Shinder, Mike Chapple

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Types of Firewalls

A variety of classification methods are used to categorize firewalls, but the most commonly used classification scheme breaks them down into the following categories:

  • Packet filtering firewalls

  • Circuit layer firewalls

  • Application layer firewalls

Some firewalls support only one of these features. Most advanced firewall products, such as Microsoft ISA Server or Check Point's Firewall-1 product, support all of these features. Firewalls become more complex to configure, and cost more, as the number of features increase.

Packet Filtering

The simplest type of firewall is the packet-filtering device. Packet filters inspect only the IP header and make allow and deny determinations—based on the source and destination IP address included ...

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