Book Review: Absolute BSD

Linh Pham []

This article originally appeared in the October 2002 issue of the Dæmon News Online Magazine. This is a cleaned-up version of the article with minor style edits and made it HTML5 compliant; else, the content has not been changed.

Author: Michael Lucas
Publisher: No Starch Press
Pages: 612
ISBN: 1-886411-74-3

Although there are several other key books out there for FreeBSD (for example: The FreeBSD Handbook, The Complete FreeBSD, and The FreeBSD Corporate Networker's Guide) that cover BSD administration, some cover too many topics or don't always provide enough details on more complex topics. Another problem with some other FreeBSD books is the fact that they can be too large to carry around and be used as a reference book. A new book on FreeBSD may just change that.

Billed as "The Ultimate Guide to FreeBSD", Absolute BSD aims to be an all-in-one guide for anyone starting in FreeBSD and UNIX administration. The author's goal was to write a guide that is both detailed yet concise (without any additional bloat) and to provide all of the information one would need to get started and confident with FreeBSD. Although FreeBSD is part of the book's title, quite a bit of the book can also be applied to NetBSD and OpenBSD, and even Darwin/Mac OS X. Like in my previous book reviews, I will provide a in-depth review of the book and comments along the way.

Below is the table of contents for the book which you can use as a reference while reading the review.

  1. Installation
  2. Getting More Help
  3. Read This Before You Break Something Else! (Backup and Recovery)
  4. Kernel Games
  5. Networking
  6. Upgrading FreeBSD
  7. Securing Your System
  8. Advanced Security Features
  9. Too Much Information About /etc
  10. Making Your System Useful
  11. Advanced Software Management
  12. Finding Hosts with DNS
  1. Managing Small Network Services
  2. Email Services
  3. Web and Ftp Services
  4. Filesystems and Disks
  5. RAID
  6. System Performance
  7. Now What's It Doing?
  8. System Crashes and Panics
  9. Desktop FreeBSD
  • Afterword
  • Appendix: Some Useful Sysctl MIBs

The book starts off with a foreword, written by Jordan Hubbard (one of the founders of The FreeBSD Project) and a brief introduction and history of BSD; a look at the different BSD operating systems and other UNIX-like operating systems; reasons for using the different BSDs and the conventions used in the book. I did find one mistake on page xxxv where Michael states, "AIX is based largely on BSD." AIX actually takes much of its heritage from AT&T/USL's System V. Although the author mentions Solaris in the list of other UNIX-like operating systems, he doesn't mention that earlier versions of SunOS was based heavily on BSD (Bill Joy was a key developer of the original BSD operating system, helped start up Sun and used BSD as a base for SunOS through SunOS 4.x).

Chapter one starts with the FreeBSD installation process for the i386 platform—it is probably quite rare to find someone without UNIX experience who would use a Digital/Compaq/HP Alpha server or workstation—by providing the minimum requirements for FreeBSD. A walkthrough of the install process using Sysinstall (including disk partitions and labelling), selecting which components to install, adding users, and configuring network interfaces is given.

There were two typos on page 14 where the author refers the reader to chapter thirteen for information on soft-updates; it should be chapter sixteen. The chapter does provide the necessary information and steps to guide the reader through a basic install while not trying to explain every single option on each screen.

The second chapter is something that some people wish it would be required reading for everyone learning FreeBSD (or any operating system or application): how to find and get help, along with what an e-mail sent to the proper FreeBSD mailing list should include. Also included in the chapter is how to use and find information in the man pages and a list of online resources that the reader can use to locate possible answers.

Backup, backup, backup! A topic that any systems administrator should know quite well, but it's something that is usually pushed off to the side. Chapter three covers how to backup and restore data using tar, dump and restore; how to control tape drives and which tape devices do what; plus a look a RCS (revision control system), single-user mode, and a brief mention of the "Fixit" disk. For those who are looking for information on how to use tape autoloaders and libraries, as well as backup software that is not included in the base system (like Amanda), will have to look elsewhere. There are two things that jumped out at me: the "-v (verbose)" tar flag was mentioned twice (once on page 42 and again on page 45) and the footnote at the bottom of page 45 is referred to on page 46.

Chapter four goes over out to optimize a FreeBSD system by using sysctl to modify some kernel settings while the system is running; work with the loader and kernel modules; making and building a custom kernel configuration to get rid of the excess that comes with the GENERIC kernel and some hints on how to use certain kernel options to boost performance.

The chapter includes some additional descriptions to commonly used kernel options, but misses a kernel option that can cause grief for those using certain types of machines: MAXMEM. On some servers, no matter what option you select in the BIOS, FreeBSD will only detect a portion of the actual memory installed, say 16MB of out of the installed 480MB. In order for the kernel to see the rest of the memory, one must set MAXMEM to the amount of memory, in kilobytes, installed. Although the problem is listed in the FreeBSD FAQ, but it still should be included in the book as some readers may have to work on hardware that behaves the way I just mentioned. (I know as I and a couple of others ran into the same issue with a certain Compaq ProLiant 2500 server.)

The fifth chapter in the book covers basic networking and network configuration concepts for FreeBSD (although much of it can also be applied to NetBSD and OpenBSD) and even contains an obligatory Monty Python reference.

The author explains the OSI model in four logical layers (Application, Logical Protocol, Physical Protocol and Physical Layer), unlike some other books that take up pages after pages explaining the OSI (which is incorrectly referred to on page 90 as "ISO") model and its seven well known layers. The author does a nice job of explaining the concepts of TCP/IP, IP addresses and subnets (even touching on slash notation along with a nice subnet mask conversion table), and Ethernet.

The last part of the chapter covers how to configure a network connection using ifconfig and route; setting up IP address aliases; and using netstat to check out what ports the system is listening on, what connections are open and a couple of useful stats. In the example the author provides for setting up IP address aliases, he omits the netmask portion of the ifconfig command, and in the ifconfig_device_alias# option in /etc/rc.conf. This can be a cause of some troubles and frustration for the reader as it may cause the system to not work as it is supposed to.

Upgrading FreeBSD, the title and focus of chapter six, can either be a breeze or cause people to have recurring nightmares. Michael explains the different branches of the FreeBSD code (-RELEASE, -STABLE and -CURRENT) and which ones are most suited for different scenarios; the two common upgrade methods (make world and sysinstall); setting up your own local CVSup mirror using net/cvsup-mirror (how apropos).

The steps outlined in the make world process is one that most seasoned FreeBSD users are accustomed to using and contain some helpful hints to reduce the chance of someone getting burned in the process, such as telling mergemaster to install a new /etc/master.passwd over an existing one). One step that wasn't mentioned in the make world process was to build and install the updated sysinstall tool as mentioned in the handbook. Including how to setup a local CVSup mirror was a really nice touch to the chapter since this can easily reduce the amount of bandwidth used for those who manage several FreeBSD servers that are being kept up to date.

Chapter seven covers some of the basic ways to secure a system: how to change the permissions and ownership on a file, setting and unsetting flags on files, using securelevels, and using sockstat to check which sockets are open and which ones shouldn't be open. When discussing how to use chmod to change the permissions of a file or directory, the examples used uses octal numbers to set the proper permissions and doesn't cover the symbol method (which uses u, g and o to signify whom and r, w and x to signify the permissions). It's more of a matter of choice and what one is used to using, so I won't be dinging any points there.

Chapter eight continues on the topic of security, but goes a bit deeper by touching on how to use TCP wrappers and how to write /etc/hosts.allow ACLs; setting up a machine to use IPFilter and writing up IPFilter rules (IPFW rules are not covered at this point in the book) and taking a look at jails and getting jails set up on a machine. To help those who are new to IPFilter, the author does a really good job of breaking down each example that he provides with a walkthrough of each keyword. He also explains any new concepts or exceptions to the rules.

One of the aspects of UNIX and UNIX-like operating systems that frightens some newcomers is the fact that almost all of the configuration is done by hacking away at text files; some have the most archaic syntax and structure (I won't name any names, but you know who you are). The configuration files under /etc are the focus of chapter nine, which tries to demystify and explain the key files along with their purpose, syntax and options.

Not every file is explained in detail in this chapter as they have already been covered or will be covered in later chapters. One set of files that are not covered are the Sendmail .cf files under /etc/mail. (The reason for this is that later in the book, the author will cover how to replace Sendmail with another MTA, or mail transfer agent.) When the author covers /etc/master.passwd, he tells the reader to use the vipw tool to make any necessary changes to the file rather than hacking the file by hand. One mistake that I did find in the explanation of the file was:

When vipw finally allows you to save your work, it also recreates the file /etc/passwd. This file can only be read by root.

The /etc/passwd is actually a world readable file; rather, /etc/master.passwd is the file that can only be read and written to by root.

Once FreeBSD has been installed on a machine and has been configured to get on the Internet and tightened down a bit, one of the next steps would be to get some programs and services installed to make the machine a useful workstation or server. Chapter ten takes a look at installing and uninstalling programs using Ports and packages; using the available make options for different purposes; how to update the Ports collection on the system; using the pkg_* tools to find out what is installed and find information about each install port or package. What is missing from the chapter (and seemingly from the rest of the book) is a look at pkgdb and portupgrade, both of which are becoming more popular and can be a lot more useful than the standard tools provided in the base system. Perhaps they will make it on to the next edition of the book.

Chapter eleven continues on the topic of running programs; working with libraries; the anatomy of an rc.d startup script; a look at the Linux, SCO, SVR4 and OSF/1 application compatibility; getting linux_base and other Linux RPM packages installed; a look at SMP (symmetric multiprocessing) and how they work with the FreeBSD kernel rounds out the chapter. On the topic of SMP, the author provides a brief history on SMP and FreeBSD, the "Big Giant Lock", the changes that FreeBSD 5.0 will bring to SMP, and a note that not all applications will benefit from having multiple processors.

The next chapter, twelve, in the book is an overview of DNS (Domain Name Service) and the BIND DNS server and toolset. The chapter starts off with an explanation of what DNS is and what role it plays, along with two tools that are used to look up DNS results and information: host and dig (nslookup is not covered since either of the two tools can be easier to use and can provide more information without messing through nslookup commands). The author continues on with an explanation of the /etc/hosts and /etc/resolv.conf files. The rest of the chapter is devoted to the configuration of BIND and setting up DNS zones which BIND will be setup to serve out.

Since the base system includes BIND 8.x instead of BIND 9.x, the chapter focuses on configuring BIND 8.x though almost all of the steps will also apply to BIND 9.x (with the exception of ndc as BIND 9.x recommends using the rndc tool, which requires some additional configuration). The author provides a good explanation of what information would go into the named.conf and DNS zone map files as it is geared towards those who are beginning to learn BIND. For those who aspire to be a BIND god/goddess, both the author and I would recommend getting DNS and BIND by Paul Albitz and Cricket Liu.

Chapter thirteen takes a look at the other network services included with FreeBSD, such as inetd, OpenSSH, and using IPFW to limit bandwidth for some or all services. The first portion of the chapter covers how to setup IPFW and Dummynet to limit the amount of traffic to a specific service to keep the rest of the bandwidth available for additional services like e-mail. (Although IPFW can be used as a firewall, like IPFilter, the steps provided are not meant for setting up a basic firewall.)

In the next portion, the author discusses the very basics of encryption, generating SSL certificates, certificate requests, setting up your own certificate authority (CA), and configuring OpenSSH; working with ntpdate and setting up your own time server using the Network Time Protocol (NTP) dæmon; and a look at inetd and its configuration file, inetd.conf. There was one minor typo on page 322 where the author mentions that ntpd's configuration file is /etc/ntpd.conf; the actual file is /etc/ntp.conf.

Chapters fourteen and fifteen cover the software behind the three most commonly used Internet services: e-mail, the Web and FTP. The first of the two chapters covers how e-mail messages are sent and gives an example of how to send an e-mail via using Telnet; the evils of allowing mail server relays; how to configure Postfix (although Sendmail and qmail are mentioned, neither of them are covered in this book); e-mail aliases and virtual domains; and setting up Qpopper for POP3 mail services. For those who are looking for help on setting up IMAP4 services, which could potentially be quite a few people, you will not find any information in the book.

One thing that needs to be noted is that in the current and possibly next printing of the book, the configuration snippets in the qpopper.conf overview are actually what Qpopper considers as the default setting. Not knowing that could cause the reader to get a bit confused while reading the descriptions of each of the key settings. The chapter rounds out with a brief overview of setting up APOP and POP3-over-SSL to help increase the security of POP3, as all of the information sent over regular POP3 is done in plain-text (just like Telnet).

The next chapter, fifteen, continues on with installing and configuring the Apache web server (focusing on Apache 1.3.x rather than Apache 2.x, though some of the configuration overview can also be used with Apache 2.x) along with setting up the included FTP dæmon. The Apache section of the chapter provides an in-depth look at the httpd.conf file; a brief touch on setting up the apache13-modssl port to use an SSL certficate; a note about how FrontPage Extensions and mod-ssl don't quite like each other; and setting up virtual hosting.

On page 372, right in between the Apache and the FTP sections of the chapter, the author mentions how to install the Microsoft .NET Shared Source Common Language Interface (or SSCLI, which has the codename, Rotor) on FreeBSD. To me, it seems like an odd place to put it since the SSCLI doesn't provide any functioning plug-ins or modules for Apache for CGI-like or Web Services usage.

Rounding out the chapter is a brief guide to using the FTP client and setting up the base system's FTP dæmon, including steps on how to cage (or chrooting users and/or groups) and tips on how to setup an anonymous FTP server.

Chapter sixteen provides an overview of what could be considered the most important parts of any BSD system: the disks and the filesystems. Without working filesystems, a system can be about as useless as a paperweight. Therefore, proper knowledge on how to take care and how to repair filesystems, along with how to mount different filesystems for data access and retrieval, is a must. The chapter covers all of those topics, along with different ways to mount a filesystem, working with the fsck (filesystem check) tool when some runs afoul, creating new filesystems (be it for BSD/UNIX or for DOS/Windows). This chapter ends with a detailed look at SCSI disks under BSD, how they need to be treated differently than IDE/ATA disks, moving files to a new partition (or directory) while maintaining the file's metadata state, and stacking mounts (along with what not to do).

One of the often ignored feature in FreeBSD (or any other operating systems that support it) is software RAID, or Vinum to be precise. The premise of chapter seventeen is RAID and using Vinum as a software RAID solution. The start of the chapter provides a look at the commonly used RAID levels (RAID-0, RAID-1, RAID-5 and RAID-10; the more obscure RAID levels like RAID-3 and RAID-4 are not mentioned or covered), what makes up a Vinum RAID array (or more appropriately, plexes) and the different plex types. To keep things sane and simple, RAID-5 and RAID-10 Vinum plexes are not covered in the chapter, but a URL for the Vinum web site is provided in case the reader is interested in configuring more complex plexes.

The author spends quite a bit of time to explain how to configure Vinum, how to create a concatenated and a mirrored plex, as well as steps to recover and re-mirror a broken mirrored plex; and he does a great job at explaining some of the possible nuances of Vinum and what to not do by hand. The only thing that was not mentioned in the chapter that I thought should have been is the fact that the plexes cannot be used as boot partitions or can be used to hold key directories that are required during the boot process.

Although setting up a RAID array or a plex may or may not increase the performance of your system, but there are other things that can hold back the system. Chapter eighteen goes in search for some of the possible performance limiting factors, as well as finding out what the culprit is. The four key performance areas that the chapter focuses on are: disk I/O, network bandwidth, processor, and memory (which also includes virtual memory, a.k.a. swap). In each of those areas, the author provides detailed information on how to use tools to monitor the resource usage (particularly top and vmstat). Also covered is how to use nice and renice to set or reset a process' priority level to allow more important processes more processing time.

The last section of the chapter runs through a couple of rounds of make buildkernel, but for each run, the author tries out different methods that would impact the performance of the build. Along with explaining the modifications made to the system or telling make to run two parallel builds (on a dual processor system), he provides stats from top and vmstat along with the results of each build. There was one mistake that jumped out at me, on page 425, where the author refers the reader to chapter fifteen for information on generating bandwidth graphs; it should be chapter nineteen.

Knowing what a system is doing and how much of it is being used are some of the most important things to know about a running system. Chapter nineteen explains some of the built-in facilities such as the Syslog dæmon (syslogd), rotating log files and how to configure newsyslog. The second half of chapter covers two often used services to grab information about a system: SNMP and MRTG. Along with explaining what MIBs (Management Information Base) are, how to view them with snmpwalk, setting up the SNMP dæmon, and using SNMP along with MRTG to generate detailed graphs displaying numerous counters and statistics. The author does a great job with explaining sometimes confusing and complex details of both SNMP and MRTG.

Chapter twenty discusses system crashes and panics, how to set up a system to allow kernel debugging and memory dumps; also using the GNU Debugger (gdb) tool to walk through memory dumps to find the failure point and the memory content when the crash or panic occurred. The second section of the chapter covers serial consoles, setting up the system to set a serial port as stdout if a keyboard isn't detected on boot, and connecting to a serial console using tip. Rounding out the chapter is a touch on problem reports (PR), using send-pr and an explanation of each of the PR fields.

Not only can FreeBSD (or any other BSD) be used as a server system, but it can also make for a good desktop system as well. Chapter twenty-one doesn't try to be the ultimate guide to setting up a FreeBSD desktop; rather, it covers some of the basics and provides suggestions for desktop programs that one can use. The first part of the chapter covers how to access Windows or Samba file shares using some of the tools that are bundled with Samba; setting up the Line Printer dæmon (lpd) to access remote and local printers; and a brief look at X Windows and XFree86, ignoring related configuration tools or files.

The rest of the chapter takes a look at some of the major application groups (like web browser, mail client, office suites, and of course, games) and some of the more popular ports from each group. You may be asking yourself why hasn't the author covered using Samba as a Windows/CIFS file server rather than just the client tools. Setting up Samba as a file server along with the myriad of configuration options could (and does) take up an entire book. Instead, the author provides a couple of resources that one can use to learn more about Samba.

The last two sections of the book are the Afterword and an appendix covering some of the more useful or commonly used Sysctl options (or MIBs). In the Afterword, the author talks about how the reader can help out in the BSD community, how not to approach the community in hopes of finding ways to help out, and the key point: be proactive and take the initiative. Within the appendix, Michael provides not only a list of common Sysctl MIBs but also tips, hints and words of caution about changing the setting or when not to change them. The list makes a great reference for any system administrator or for someone who likes to find ways to tweak his/her machine just to see what happens.

Although the book is over 600 pages, a majority of the pages are packed with a lot of information while not taking up full pages for self-explanatory screenshots or code/configuration examples. I think that the author's goal for the book has been met as key topics like backup and recovery, security, analyzing the system's performance and usage, and major services (viz., DNS, mail and web) are covered. Some readers may feel a bit empty owing to lacking or missing coverage on how to setup Samba for Windows/SMB file and print serving, and XFree86 configuration. Both topics are covered in grand details in other books or on-line documentation, but having to look elsewhere may irk a few readers.

Overall, the book was well written and tries to keep the reader's attention by including humorous commentaries and notes while staying on topic. Ramblings and rants are kept to a bare, bare minimum. Being the first edition and printing of the book, there were several errors/mistakes and a couple of typographical errors throughout the book. (I have brought the errors and mistakes that I have found to the author and most, if not all, of them have been corrected for future printings and editions. An errata for the book should be available on the book's website at There are also a couple of topics that could have made a mention of additional tools; in particular, there was no mention of the portupgrade and pkgdb tools in the chapter ten.

Now, would I recommend this book? I think that the book should be highly recommended for those who have worked with FreeBSD for a while, but would like to learn a bit more about the included services. For anyone wanting to learn FreeBSD to set up a server, I think it would be useful--even for those with a bit of Linux experience. The book is definitely worth looking at for those who are well seasoned with FreeBSD and it could be a great complement to the other documentation available on-line or in book format.

Article copyright © 2002–2010 Linh Pham. All rights reserved. Re-production of portions of this work, or its entirety, requires permission of the copyright holder.