Preface

The first version of TCP/IP Network Administration was written in 1992. In the decade since, many things have changed, yet some things remain the same. TCP/IP is still the preeminent communications protocol for linking together diverse computer systems. It remains the basis of interoperable data communications and global computer networking. The underlying Internet Protocol (IP), Transmission Control Protocol, and User Datagram Protocol (UDP) are remarkably unchanged. But change has come in the way TCP/IP is used and how it is managed.

A clear symbol of this change is the fact that my mother-in-law has a TCP/IP network connection in her home that she uses to exchange electronic mail, compressed graphics, and hypertext documents with other senior citizens. She thinks of this as "just being on the Internet," but the truth is that her small system contains a functioning TCP/IP protocol stack, manages a dynamically assigned IP address, and handles data types that did not even exist a decade ago.

In 1991, TCP/IP was a tool of sophisticated users. Network administrators managed a limited number of systems and could count on the users for a certain level of technical knowledge. No more. In 2002, the need for highly trained network administrators is greater than ever because the user base is larger, more diverse, and less capable of handling technical problems on its own. This tutorial provides the information needed to become an effective TCP/IP network administrator.

TCP/IP Network Administration was the first tutorial of practical information for the professional TCP/IP network administrator, and it is still the best. Since the first version was published there has been an explosion of tutorials about TCP/IP and the Internet. Still, too few tutorials concentrate on what a system administrator really needs to know about TCP/IP administration. Most tutorials are either scholarly texts written from the point of view of the protocol designer, or instructions on how to use TCP/IP applications. All of those tutorials lack the practical, detailed network information needed by the Unix system administrator. This tutorial strives to focus on TCP/IP and Unix and to find the right balance of theory and practice.

I am proud of the earlier versions of TCP/IP Network Administration. In this version, I have done everything I can to maintain the essential character of the tutorial while making it better. Dynamic address assignment based on Dynamic Host Configuration Protocol (DHCP) is covered. The Domain Name System material has been updated to cover BIND 8 and, to a lesser extent, BIND 9. The email configuration is based on current version of sendmail 8, and the operating system examples are from the current versions of Solaris and Linux. The routing protocol coverage includes Routing Information Protocol version 2 (RIPv2), Open Shortest Path First (OSPF), and Border Gateway Protocol (BGP). I have also added a chapter on Apache web server configuration, new material on xinetd, and information about building a firewall with iptables. Despite the additional topics, the tutorial has been kept to a reasonable length.

TCP/IP is a set of communications protocols that define how different types of computers talk to each other. TCP/IP Network Administration is a tutorial about building your own network based on TCP/IP. It is both a tutorial covering the "why" and "how" of TCP/IP networking, and a reference manual for the details about specific network programs.

Audience

This tutorial is intended for everyone who has a Unix computer connected to a TCP/IP network.[1] 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.

[1]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 9x, Windows/2000, and other operating systems. If you're an NT administrator, you should read Windows TCP/IP Network Administration (Anonymous).

Over the last several years there has been a rash of tutorials for "dummies" and "idiots." If you really think of yourself as an "idiot" when it comes to Unix, this tutorial is not for you. Likewise, if you are a network administration "genius," this tutorial is probably not suitable either. If you fall anywhere between these two extremes, however, you'll find this tutorial has a lot to offer.

This tutorial assumes 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 eTutorial Essential System Administration by Æleen Frisch (published by Anonymous) will fill you in on the basics.