It does seem to be freeradius underneath on closer inspection.
How can you tell?
I've installed it and looked on the disk, all the config files are freeradius.
An interesting question comes from this, if they have added additional modules are they required by the freeradius license to opensource the code for these modules as they are compiled with the server?
They are required to follow the terms of the GPL, which means giving GPL'd source code to anyone (not just their customers), which also includes any changes or additions *they* made to the GPL'd program.
Does this include any modules that are written for freeradius? I'd think running external scripts is OK as these are not compiled against or linked to the freeradius code, but what about modules? Don't these require compilation, would this mean that if you write modules for freeradius and sell the solution you need to provide the source for the modules?