5.1 Introduction to FreeRADIUS

The developers of FreeRADIUS speak on their product and its development, from the FreeRADIUS web site:

FreeRADIUS is one of the most modular and featureful [sic] RADIUS servers available today. It has been written by a team of developers who have more than a decade of collective experience in implementing and deploying RADIUS software, in software engineering, and in Unix package management. The product is the result of synergy between many of the best-known names in free software-based RADIUS implementations, including several developers of the Debian GNU/Linux operating system, and is distributed under the GNU GPL (version 2).

FreeRADIUS is a complete rewrite, ground-up compilation of a RADIUS server. The configuration files exhibit many similarities to the old Livingston RADIUS server. The product includes support for:

• Limiting the maximum number of simultaneous logons, even on a per-user basis

• More than one DEFAULT entry, with each being capable of "falling through" to the next

• Permitting and denying access to users based on the huntgroup to which they are connected

• Setting certain parameters to be huntgroup specific

• Intelligent "hints" files that select authentication protocols based on the syntax of the username

• Executing external programs upon successful login

• Using the $INCLUDE filename format with configuration, users, and dictionary files

• Vendor-specific attributes

• Acting as a proxy RADIUS server

FreeRADIUS supports the following popular NAS equipment:

• 3Com/USR Hiper Arc Total Control

• 3Com/USR NetServer

• 3Com/USR TotalControl

• Ascend Max 4000 family

• Cisco Access Server family

• Cistron PortSlave

• Computone PowerRack

• Cyclades PathRAS

• Livingston PortMaster

• Multitech CommPlete Server

• Patton 2800 family

FreeRADIUS is available for a wide range of platforms, including Linux, FreeBSD, OpenBSD, OSF/Unix, and Solaris. For the purposes of this book, I will focus on FreeRADIUS running under Linux. Also, as of this printing, a stable Version 1.0 of the product had not been released. However, development of the server is very stable, careful, and somewhat slow, so changes to the procedures mentioned are unlikely. In the event a procedure does change, it's likely to be a relatively small modification. Always check the FreeRADIUS web site for up-to-date details.