I have 802.1x/peap authentication in my wireless network with ACS 4.2 as the authentication server. I enabled PEAP machine authentication under the Unknown user policy --->database configuration sub-menu. I discovered that I was still able to access the wireless network on my android phone with my domain logon. I later discovered that there is an option in Group policy to force Windows XP clients to perform computer authentication. Now the problem is that windows 7 clients do not have the EAPOL option in the registry, hence the group policy object may not work.
Please could any one suggest how to enforce machine authentication and stop unwanted devices without having to purchase a NAC server.