| Overview

This module will examine how the PIX Security Appliance interacts with network traffic beginning with a review of Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) sessions. The student will then find out how these sessions are allowed through the PIX Security Appliance.

One aspect of understanding how TCP and UDP work with the PIX is examining both translations and connections. It is important to learn how these items are used when traffic is going from the inside network to the outside network, or from the outside network to the inside network. In examining translations and connections, four types of Network Address Translations (NATs) are discussed. Additionally, configuring Domain Name System (DNS) support, doctoring DNS, and the

alias command are examined.

Finally, Port Address Translation (PAT) and configuring multiple interfaces on the PIX Security Appliance are discussed. PAT is a translation method, like NAT, that allows network administrators to hide the inside network addressing scheme from outside hosts and allows for the conservation of IP addresses. However, unlike NAT, which leases IP addresses to inside hosts on a one-to-one basis, PAT is able to go a step further and allow numerous inside hosts to use a single IP address. This process is called overloading.

To configure multiple interfaces, this module will discuss how the PIX Security Appliance supports up to eight additional perimeter interfaces. The student will gain experience configuring multiple interfaces in a lab that is presented at the end of the module.

NOTE: It is required that the student study the commands covered in the chapter using the labs and the command reference. Not all required commands are covered in sufficient detail in the text alone. Successful completion of this course requires a thorough knowledge of command syntax and application.