As we rely more and more on massively interconnected networks, the stability and security of these networks is more vital than ever. The world of business has adopted information technology to help streamline their processes, increase productivity, and cut costs. As such, a company's IT infrastructure is a core asset to many businesses. Because of this, many businesses would cease to function if disaster (whether natural or digital) were to disrupt their network operations in a significant way. At the same time, the widespread adoption of the Internet as a global communications medium has also brought computer networks out of the business and academic world and into our personal lives, where it is used not only for entertainment, but also as a means to keep in touch with friends, family, and loved ones.
Although this book as a whole is meant to address network security, the information it contains extends into many other areas. After all, a network is simply a means to connect machines and services together so that they can communicate. This chapter, however, deals primarily with the security and integrity of the network itself. In this chapter, you'll learn how to detect and prevent certain types of spoofing attacks that can be used to compromise the core integrity of a TCP/IP Ethernet network at its lowest level. This chapter also includes a great deal of information about firewalls, discussing everything from basic port-based firewalling to MAC-address filtering, and even shows you how to create a gateway that will authenticate machines based on login credentials.
Although it is not always a direct security threat, network reconnaissance is often a precursor to an attack. In this chapter, you'll learn how to fool those who are trying to gather information about the hosts on your network, as well as ways to detect eavesdroppers who are monitoring your network for juicy bits of information.