Firewalls

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3

Firewall Types

3.1 Chapter objectives

■ Identifying the advantages and disadvantages of stateless and

stateful packet filters

■ Implementing circuit-level gateways

■ Certifying application proxies

■ Selecting criteria

As previously explained, a firewall puts up a barrier that controls the

flow of traffic among domains, hosts, and networks. The safest firewall

blocks all traffic, but that defeats the purpose of making the

connection. According to a logical security policy, you need strict

control over selected traffic. Organizations typically put a firewall

between the public Internet and a private and trusted network.

A firewall can also conceal the topology ...