Preface There are a lot of documents, books, whitepapers, HOWTOs, and other guides, written about network administration generally, and Linux specifically. Indeed, I reference many of these throughout this book. There are, however, two things that these resources do not do. First, the coverage of the TCP/IP stack is usually either completely theoretical or minimized. The importance of associating implementation considerations, troubleshooting methods, and performance analysis with the functionality of each layer within the TCP/IP stack cannot be overstated. I am of the firm opinion that the theory of the stack and the application of the stack should be presented simultaneously. This I have endeavored to do in the first nine chapters. Second, few resources provide any useful implementation information about routing table management protocols like OSPF and BGP.

I have a whole bunch of horror stories relating to my early efforts at implementing OSPF and the fruits of those efforts are covered in Chapters 11 and 12. Unfortunately, I only had time to cover gated. At some future point, I hope to have the opportunity to add details about zebra. Additionally, I cover the basics of BGP as implemented by the public version of gated in Chapter 13. These chapters should give most modestly seasoned network administrators enough to go on to get one or more of these protocols functional. I think that these topics alone give credence to this book. However, I tried to round out the work with some topics of general interest to network administrators. In particular, I give an introductory treatment of implementing packet filtering with ipchains and iptables in Chapters 14 and 15, respectively.

I also cover some of the very exciting advanced Linux capabilities including routing policies, tunneling, and traffic control in Chapter 16. Finally, Chapter 10 touches on the basic network applications, including DHCP, DNS, NFS, Samba, NIS, and LDAP. These topics are covered lightly with extensive reference details for further study. I must confess that I do regret not being able to include a more thorough treatment of certain topics. In particular, the coverage of TCP, IPv6, multicast routing, and SNMP should have considerably more attention. Other areas such as coverage of iptables and tc could certainly be enhanced. On the other hand, the book is already at about 800 pages and took nine months to write (I still have a day job). So, hopefully, this a good resource as it is and a good first step toward an even better resource a year or two down the road.

I certainly hope that you benefit from it. A Note about Linux Distributions Throughout the book, I have attempted to address a number of different Linux distributions. In particular, I specifically address Red Hat 6.2/7.0, Caldera 2.4, SuSE 6.4, and Debian 2.1.

The versions for each distribution reflect the latest available at the time of this writing. Linux Documentation Throughout the book, I generally assume that you will know where to find the basic Linux documentation. So whenever I reference a HOWTO or Linux Guide or FAQ, I mean the document that can be found at the Linux Documentation Project (LDP) home page, namely http://www.linuxdoc.org/ I also reference manpages by title(section number) . For instance,passwd(5)refers to thepasswd manpage found in section 5 of the manual page catalogue. More often than not, the section number is irrelevant as there is only onemanpage of the given name. However, sometimes, and in this particular case, there are multiplemanpages related to the given name.

In the case ofpasswdthere are two pages, one in section 1 and the other in section 5. The commandman passwdwill bring up the man page forpasswd(1). You can scroll down and eventually get topasswd(5), but you can execute the commandman 5 passwdto obtain thepasswd(5)page immediately. Seeman(1) for further details. Prerequisites I do make certain assumptions about your knowledge. In general, I expect that you have some knowledge of system administration and, in particular, are familiar with the following or their equivalents. an editor such as vi, emacs, or your favorite GUI text editor kernel rebuilding and the use of commands like insmod,modprobe, andlsmod system start/stop or start-up scripts, that is, /etc/rc*and/etc/init.d/* syslogand the/etc/syslog.

conf file logical operators like &, , and ! I also assume general familiarity with the Linux environment including the X Window system and the use of the X Window manager of your choice. Errata and Contacts If you discover anything that is incorrect or that is confusing or has some problem, please let me know! Send email to me at linux_upat@thekeyboard.com I won''t always answer, but I will review any corrections, comments, and recommendations. I will post updates and corrections to a site that you''ll find a link to off this book''s catalog page on phptr.com: http://www.phptr.com/ptrbooks/ptr_0130322202.html.