Setup Freeradius for Challenge response authentication

[Alan DeKok]

Yizhi Lao <laoyizhi at yahoo.com> wrote:
>    I am a new user of freeradius, currently using freeradius 1.1.0 on Redhat Linux. I wish to setup freeradius for a 2 factor authentication, such that:
> 
>   NAS issue an Access-Request to Radius server
>   Radius server authenticate against LDAP
>   once successful --
>   Radius server then issue an Access-Chanllenge  to NAS (second factor, asking for  an additional password/token)
>   NAS reply with an Acces-Request
>   Radius server then authenticate the second Access-request and reply to NAS.

  This is a very unusual request, since it isn't tied to an
authentication method.  You will have to write a module to do this.

  Alan DeKok.