This book is intended for everyone who has a UNIX computer connected to a TCP/IP network.  This obviously includes the network managers and the system administrators who are responsible for setting up and running computers and networks, but it also includes any user who wants to understand how his or her computer communicates with other systems. The distinction between a "system administrator" and an "end user" is a fuzzy one. You may think of yourself as an end user, but if you have a UNIX workstation on your desk, you're probably also involved in system administration tasks.
 Much of this text also applies to non-UNIX systems. Many of the file formats and commands, and all of the protocol descriptions apply equally well to Windows 95, Windows NT, and other operating systems. If you're an NT administrator, don't worry. I'm currently writing an NT version of this book.
In recent years there has been a rash of books for "dummies" and "idiots." If you really think of yourself as an "idiot" when it comes to UNIX, this book is not for you. Likewise, if you are a network administration "genius," this book is probably not suitable. If you fall anywhere between these two extremes, however, you'll find this book has a lot to offer.
We assume that you have a good understanding of computers and their operation, and that you're generally familiar with UNIX system administration. If you're not, the Nutshell Handbook Essential System Administration by Æleen Frisch (published by O'Reilly & Associates) will fill you in on the basics.