Introduction

With the proliferation of wireless access points (WAPs), virtual private networks (VPNs), and extranets, it s becoming increasingly difficult to determine where your network begins and ends. Add this complexity to common economic factors, such as company mergers and acquisitions, and now you have a tangled web of interconnected segments and networks that you will need to understand. While this book aims at providing you the necessary tools to protect your network infrastructure assets, it is imperative that before we dive into the details you have a good understanding of how your network is designed.

Having a commanding knowledge of your network topology today is no simple feat. We are often reminded of a financial services company at which we performed some consulting work. This company has grown over the past few years by acquiring related financial companies. At the end of the day, this team of network engineers had to manage over 300 Frame Relay lines, over 100 Microsoft Windows NT 4.0 domains, and numerous Internet access points (IAPs). To add insult to injury, these networks are not static environments; in fact, there are numerous routing changes and firewall modifications made on a daily basis. The only saving grace this team of dedicated foot soldiers has are solid topology diagrams detailing each Frame Relay network and IAP, and a comprehensive list of all of their outwardly facing IP addresses.

While these tools sound like networking basics, we are constantly surprised at the number of IT departments that are without...