Hi Biju,
You can use Cisco's ACS 5.x as either a hardened Linux appliance or a VMWare image. It has good AD integration and the process for ACS 5.x authenticating to an AD backend takes only a few minutes. There are just a few steps and it goes like this:
1) In the "Network Resources" pane:
-Define your wireless controllers or autonomous APs, check the RADIUS box, and set the secret that is shared with your wireless APs.
2) In the "Users and Identity Stores" pane:
-Define your AD domain and credentials to access your AD tree.
3) In the "Access Policies" pane:
-Define an access policy (selecting the MS-CHAPv2 and probably PEAP protocals) for your wireless authentication, say Cisco-Wireless.
-Define a "Service Selection Rule" and from the "Results -> Service" dropdown select Cisco-Wireless access service you already made.
Now you have an access policy named Cisco-Wireless with two categories: Identity & Authorization.
-Identity - Leave at default of "Single result selection" since all AD users are allowed access.
-Authorization - You don't need any rules since you aren't discriminating among AD users (if they can authenticate to AD they are fully authorized for network access). Just set the default rule at the bottom to "permit access."
4) Install SSL certs:
In the "Users and Identity Stores" pane:
-Add a root CA or intermediate cert to "Certificate Authorities." (For example a Verisign intermediate cert)
In the "System Administration" pane:
-Add an EAP certificate in the "Local Certificates" section and add your CA signed cert.
For particulars of getting a CA signed cert for ACS 5.x, refer to this: https://supportforums.cisco.com/message/3065177#3065177
That's it. Enjoy.
Mark
