Mastering™ Network Security, Second Edition

6.3. Configuring PIX

You can use PIX in any of the three primary firewall configurations: bastion, three-way, or back-to-back. The basic models (like the one we're demonstrating) work with only two interfaces: inside and outside. Typically, however, you use PIX in a three-way firewall, acting as the central control point between the external network, the DMZ (De-Militarised Zone), and the internal network. In other words, all network traffic between the external network and your DMZ and internal networks flows through, and is subject to, the firewall.

PIX is preconfigured with two interfaces that are simply referred to as inside and outside. PIX uses security levels to determine how filtering rules are applied to the interfaces. (You can define ...