• Identify the need for network security

• Recognize the causes of network security problems

• Distinguish the four primary types of threats

• Know the four primary types of network attack

• Discover Cisco AVVID and SAFE, and how they relate to network security

• Learn about the Cisco Security Wheel

• Understand network security policy

• Improve network security

To understand, in part, why we are where we are today, you only have to remember that PC is the acronym for personal computer. The PC was born and, for many years, evolved as the tool of the individual. In fact, much of the early interest and growth came as a rebellion to what appeared as exclusionary attitudes and many restrictions of early data-processing departments. Admittedly, many PCs were tethered to company networks, but even then there was often considerable flexibility in software selection, settings preferences, and even sharing of resources such as folders and printers.

As a result, a huge industry of producers developed and sold devices, software, and services targeted at meeting user interests and needs, often with little or no thought about security. Prior to the Internet, a person could keep their computer resources safe simply by being careful about shared floppy disks.

This book provides a variety of techniques and technologies to protect computing resources from unauthorized access and loss. This chapter lays the foundation by looking at the need for network security. What are the threats? Who are these people who threaten the data, and what are some of the methods they use? In addition, you’ll find many references to outside resources for additional information.

While this book addresses the requirements of the various certification exams, recognizing that the diversity of security threats is far too large for any single book is important. Furthermore, the nature and source of many threats changes on a daily basis, making it important to start building a set of resources, such as web sites, news groups, trade associations, vendor distribution lists, and so forth that can help you try to stay abreast of the changes. Each technology, such as wireless, voice, web pages, and e-mail systems, has its own set of threats that a person must remain aware of.