... of the time security was an afterthought Why Network Security Is Necessary Today, the Internet is made up of tens of thousands of networks, interconnected without boundary Network security is ... stop the source(s) CiscoSecurePIX.book Page 10 Friday, November 16, 2001 10:35 AM 10 Chapter 1: Introduction to Network Security Network Security Policy and the Security Wheel Network security is ... illustrates the four steps of the Security Wheel Figure 1-2 The Security Wheel CiscoSecurePIX.book Page 11 Friday, November 16, 2001 10:35 AM Network Security Policy and the Security Wheel 11 The security...