Firewalls and Internet Security: Repelling the Wily Hacker, Second Edition

Chapter 2. A Security Review of Protocols: Lower Layers

In the next two chapters, we present an overview of the TCP/IP protocol suite. This chapter covers the lower layers and some basic infrastructure protocols, such as DNS; the next chapter discusses middleware and applications. Although we realize that this is familiar material to many people who read this book, we suggest that you not skip the chapter; our focus here is on security, so we discuss the protocols and areas of possible danger in that light.

A word of caution: A security-minded system administrator often has a completely different view of a network service than a user does. These two parties are often at opposite ends of the security/convenience balance. Our viewpoint is tilted ...