[xwiki-users] Restricting rights of non-logged-in users

Hello, I would like to restrict non-registered and non-logged-in users, so that the only pages/spaces they can view are Log-in and Registration pages. For example, at present a non-logged-in and non-registered user can see the xwiki Main space. I do not want to allow these users to see Main, or any other spaces, until after they are registered and logged-in. Is there anyway this can be done? Thank you, --Tom