Master one single topic, and everything becomes clearer.

The field of network security is a huge subject. To be a network security expert, you must be an expert on routers, switches, hubs, firewalls, intrusion detection systems (IDS), servers, desktops, email, HTTP, instant messages, sniffers, and a thousand other topics. There are many books on network security, and the good ones tend to be tomes of 1000+ pages that are intimidating even to their authors. This book takes the opposite approach. It takes a single, but vitally important, topic and expands on it. Routers are your first line of defense. If they are compromised, everything else is compromised. This book describes how to secure your routers. Once you learn how to secure them, routers can protect the rest of your network.

To reemphasize, this is not a book on network security; there are hundreds of those already in print. You will not find long discussions on firewalls, Virtual Private Networks (VPNs), network IDS systems, or even access lists (ACLs). This book is more fundamental than that. This book shows how to harden the foundation of your network— the router. Once you have mastered the information in this book, you will find that your ability to build firewalls and configure IDS systems will increase. You will be building on a secure foundation.