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 this information. Without
knowing how your network is laid out, or understanding which segments touch
the Internet directly, it will be nearly impossible for you to begin locking down
your network devices. If you are not armed with these tools already, this chapter
will help you find your external IP address presence and help you get a handle
on understanding the differences between your core network segments and those
that lie on your perimeter. Chapter 2, “Assessing Your Current Network,” will
help provide you with those all-important topology maps if you aren’t fortunate
enough to have them in your toolbox already. Furthermore, the end goal of this
chapter is to arrive at common language that can be easily understood, and used
throughout the entirety of the book.