© 2013 Warren Block

Last updated 2013-07-29

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An encyclopedic look at OpenBSD.

Disclaimer: the publisher offered me a copy of this book with the stipulation that I would write a review of it. This is that review.


OpenBSD’s influence is pervasive. All sorts of things have originated there and moved into mainstream usage. For me, OpenBSD is something I’ve respected and been aware of, but have rarely used directly.


Every operating system book has to have a section on installation. Many put a great emphasis on it. Sometimes it seems like more than half of a book is dedicated to it. But on a decent operating system, installation is a one-time thing. This book has clear and reasonable coverage of installation and initial configuration, then gets on to more important things, configuring and using the services that OpenBSD provides.


Most of the book is dedicated to configuring the OpenBSD system, and rightly so. That is what most users of OpenBSD will need immediately. The trick is not just to show typical configurations, but explain the specifics of the options used, and Michael Lucas does just that. The language is informal and casual without being patronizing, and the clarity is excellent.


There is lots of information in this book that is clear, complete, and also applies to other operating systems.

For example, sudo is treated by many as a magic safety helmet. Just use it, and somehow it makes things secure. That is not done here. Instead, there is a detailed section on configuration along with common mistakes and misconceptions.

A clear and simple section on NFS is followed by an excellent overview of system security, which in turn is followed by a very clear short-form coverage of TCP/IP including IPv6. Two full chapters are devoted to PF, OpenBSD’s flagship firewall.


Do you need this book? If you use OpenBSD, and have not yet achieved guru status, yes, this book is just for you. Even gurus will find valuable things in this book that they did not know.

But beyond the OpenBSD aspect, there are great sections on cross-platform applications like sudo that are almost enough on their own to justify getting this book. And there are several of those chapters. So: even if you don’t use OpenBSD directly, would you like a quick reference on sudo, IPv6 networking, and NFS setup? Oh, and also tftpd, PXE, and diskless BSD systems? But wait, what if I told you these references came with a free book on OpenBSD installation and configuration?

Absolute OpenBSD, 2nd Edition by Michael Lucas, is published by No Starch Press.