In this chapter we reviewed the many different fundamental concepts that are important to networking. First we reviewed the OSI model. As you can see, the OSI model is very important to understand. It is used throughout this book and other documentation. In fact, almost any documentation referencing networking uses the OSI model as a base to explain how networking functions. An important fact to remember is that the OSI model is just that; a model. As you saw in the explanation of the TCP/IP model, the OSI model does not exactly fit together with TCP/IP. However, once you understand TCP/IP and how it works you will understand it for all platforms and applications.

If you were to truly have a book titled Understanding Security Basics, it could easily span over a thousand pages. In this chapter we have brought together a concise version of that material to help you begin to understand the expansive world that is security. In the battle for the secure enterprise, the most important thing to remember is that there is no single solution to secure everything. Many products claim to have the silver bullet for securing your network, but this is nothing more than marketing. Each company has different restrictions on resources and has different security requirements.

In the last section we reviewed the basics of firewalls. The evolution of firewalls has been a long and harrowed path. As new threats come to light there will always be new technologies that will be...