I read the following book for a review:

FreeRADIUS Beginner's Guide (paperback)

There is also a Kindle version here:

FreeRADIUS Beginner's Guide (Kindle edition)

Also available directly from PACKT Publishing (physical or ebook) following This link

here is my review (note this review is from when the book was published, some time ago! The world has moved on from FreeRADIUS 2 but actually the methods and the underlying principles still remain in FreeRADIUS 3 )

Book review: FreeRADIUS Beginner's Guide
There are quite a few RADIUS books on the market so when I saw a new one entitled "FreeRADIUS Beginner's Guide - Manage your network resources with FreeRADIUS" By Dirk van der Walt, I did ponder about what audience it was aimed at. However, as the UK support for eduroam and the contact point for UK higher/further education RADIUS proxying I thought it best that I read it to see what it offered. So I downloaded the ebook from the Packt publishing page: http://www.packtpub.com/freeradius-master-authentication-authorization-accessing-your-network-resources/book?tag=rk/freeradiusbg-abr1/0911 (Printed copies are also available for a reasonable price).
Within a couple of hours of starting to read the book I was impressed with the material offered. The author starts off with a brief introduction and then its straight into FreeRADIUS itself. Installing the server by distribution package is covered and how to compile from source...however this mainly focuses on how to install by source package rather than from the main download site - I personally prefer getting the source direct. The author has clearly spent a lot of time using FreeRADIUS for specific tasks - there is quite a lot of Microtik and hotspot accounting material present in the book but that does detract from the overall content. Some functions of FreeRADIUS are not covered in depth with some modules given the light look or ignored, however the book does deliver in its promise of getting a FreeRADIUS newbie to a reasonable knowledge level before the end page. The book is targeted to the current version of FreeRADIUS (version 2) which is refreshing and it also covers and demystifies the built in configuration language 'unlang' - which is also a great starting point. I feel that this book is ideal for any RADIUS administrator who wants to operate FreeRADIUS (experience of the Linux operating system on which you'd run FreeRADIUS is taken for granted) and if an administrator read this book then it would give them a strong grounding in the subject and avoid a lot of beginner errors. Anyone who has read this book is also far less likely to ask trivial questions on the official FreeRADIUS users mailing list.
There are a few typos and minor errors in the text - Packt publishing have a good errata system so these errors should be removed from the next edition of the book - but none of them are critical. The author covers useful testing methods - JRADIUSSimulator , which is a useful tool but FreeRADIUS comes with a suite of testing tools and there are alternatives that are well known by people in the sector, such as eapol_test. The small bits of code used in the book are also downloadable from the Packt publishing page for the book which is very useful for the beginner who may not have any scripting ability - nothing worse than everything failing due to a typo when following a tutorial, especially if you are dealing with new concepts. The book mentions eduroam, an international federated authentication system using RADIUS proxying but doesn't go into great detail - but the foundations and grounding for how it operates are well covered within the pages so the final requirements for a site shouldn't be daunting (a bit of 'unlang', some work in the proxy configuration and doing some attribute and dictionary work).
Since reading this book I have recommended it to several people in the sector and to a couple of sites that I have done RADIUS consultancy work for. Anyone who uses FreeRADIUS but has never been happy with current books on offer or how the server works should buy a copy of this book. The only thing missing? An 'advanced users' companion book :-)