Thanks Alan and Peter for your fast answers.
After doing some tests with the suggested tools I found no "ready to use" simulator for testing 2 step authentication with challenge response messages.
I tried Jradius simulator which also seems not to have this feature. I will try to code myself something with the suggested libraries and tools. Thanks, Greg - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
