# /etc/freeradius/3.0/sites-enabled/default

...

authorize {
...
	if(!control:Auth-Type) {
		update control {
			Auth-Type = "ntlm_auth"
		}
	}
}

authenticate {

	Auth-Type PAP {
		pap
	}
	
	Auth-Type NTLM_AUTH {
		ntlm_auth
	}

...
}