FreeRadius Server setup and configuration under OpenWrt Attitude Adjustment 12.09. Please watch at 1080p.
In order to have a working freeradius setup, you need to edit some files under /etc/freeradius2/ (users, clients.conf, radiusd.conf and eap.conf), create certificates (openssl-util package is needed for this) and configure the wifi interface so it uses WPA2-EAP encryption. (You may have to remove wpad-mini package and install wpad which includes support for WPA2-EAP).
For FreeRadius3, you have to edit these files:
/etc/freeradius3/mods-config/files/authorize
/etc/freeradius3/radiusd.conf
/etc/freeradius3/clients.conf
/etc/freeradius3/mods-available/eap
When you have done all the above, enable and start the freeradius server (/etc/init.d/radiusd enable, /etc/init.d/radiusd start) and test your config.