Radius Test a suite of Radius testing tools, includes RadTest and RadEapTest. RadTest is a GUI based extensible RADIUS testing tool, It can be used to test changes you made in the configuration of the radius server, or it can be used to monitor if a radius server is up. Through RadTest you can simulate authentication and accounting request and send them to the RADIUS server making Radius Test act as a NAS client, then shows the reply.

RadEapTest is a GUI based RADIUS testing tool used for testing radius EAP methods. It integrates IEEE 802.1X Authenticator (normally, an access point) and IEEE 802.1X Supplicant (normally, a wireless client) together to generate a single program that can be used to test EAP methods without having to setup an access point and a wireless client. The main uses for RadEapTest are in interoperability testing of EAP methods against RADIUS servers.
Radius Test works on MS Windows 7/Vista/XP/2000/NT4.x and 2008/2003 Server.

RADIUS (Remote Authentication Dial In User Service) is an Internet standard defined in RFC 2865. Internet service providers use RADIUS to authenticate dial-in users. RADIUS was subsequently extended to support accounting as defined in RFC 2866.

Radius Test Features:
1. Easy-to-Use Windows Interface, simple setup lets you start right away
2. Support EAP methods: EAP-MD5,EAP-MSCHAPV2,EAP-OTP,EAP-GTC,EAP-TLS,EAP-PEAP,EAP-TTLS,EAP-LEAP
3. Support upload and delete Vendor Dictionaries. This will provide access to the associated Vendor Specific Attributes for use in Functional and Performance tests.
4. Attribute profiles allow you to store multiple sets of authentication or accounting requests for various purposes.
5. Repeat send packet.
6. Send packet in parallel.
7. Schedule Sending packet.
8. Provide two command-line tools (radclient.exe and radeapclient.exe) that you can use to do a more in-depth tests.

RADIUS allows vendors to add attributes relevant to them as part of aforementioned messages. This enables vendors to essentially extend the RADIUS implementation while allowing them to carry business critical information in these messages - this is done via vendor-specific-attributes (VSAs). VSAs, while offering flexibility, preclude interoperability with standard RADIUS servers. Also, there seems to be a general lack of elegant tools to add VSAs.

The license of this software is Free Trial Software, the price is $29.95, you can free download and get a free trial.