What if we flew in computers? That gives "crash" a whole new meaning, doesn't it? Well, if we did, I am sure you would agree that we would all be dead. I would love to say operating systems are really improving, but it isn't so. I installed XP SP2 beta, one of the least-rickety operating systems I have worked with in a long time, on a clone of my primary laptop a couple months ago, and it has been interesting. As soon as I submit the remainder of my chapters for this book, I will upgrade my production box. As I write this, the Windows update version has still not been released, and it will be very interesting to see what breaks when the home users get upgraded. A lot of people died in the early days of the airline industry, and as I say, if we flew in those early planes today, most of us would be dead.
Now here is the kicker: IPS systems and intelligent switches are nothing but software applications or ASICs that are built on these rickety operating systems. One of the primary themes of this book is never to trust the operating system, to expect perimeter components to fail. This book will show you techniques for failover, layering defense components, segmenting internal networks, using instrumentation to detect anomalies, and troubleshooting. In the early days of perimeter defense, the only choice that information security practitioners had was to layer their perimeter software on these rickety operating systems.