Update devise model to use kerberos

app/models/user.rb

@@ -3,7 +3,7 @@ class User < ActiveRecord::Base
   # :token_authenticatable, :confirmable,
   # :lockable, :timeoutable and :omniauthable
   devise :database_authenticatable, :rememberable, :trackable, :validatable,
-    :pam_authenticatable
+    :kerberos_authenticatable
 
   # Setup accessible (or protected) attributes for your model
   attr_accessible :email, :password, :password_confirmation, :remember_me