RADIUS

Interlink Networks
Providers of servers, network appliances and consulting. Site includes user group functionality.
http://www.interlinknetworks.com

radiusContext
A python log analyzer for servers. Available under the Open Source license. Includes advantages and disadvantages, usage information, and latest features.
http://www.tummy.com/Community/software/radiuscontext/

WinRadius
Standard RADIUS server for network authentication and accounting.
http://www.itconsult2000.com/en/product/WinRadius.html

CERT Advisory: Vulnerabilities in Various Implementations of the RADIUS Protocol
Covers two vulnerabilities: the digest calculation buffer overflow, and the inadequate validation of the vendor-length of vendor-specific attributes. <small>(March 4, 2002)</small>
http://www.cert.org/advisories/CA-2002-06.html