How limit forums to authenticated users?

I would like to make the forums of the site off-limits to visitors who have not authenticated, but I don't see how to do that.

In admin/user/access, both anonymous user and authenticated user need to have access control to node module > access content, otherwise they can't even read the home page. But when the anonymous user can access that content, they can also access the forums. I don't see away to distinguish forums content from plain old content like the homepage.

Is there a way to give authenticating users a menu item to the forums, that is not visible to the anonymous user?