Hi. I'd like to create an HTML page for my forum, but only visible to logged in users. Is there a way to do that?

Right now the only thing I can think of is to make a custom portal widget, which of course would only appear on the portal.

I don't know of a way to restrict access to the page itself, but you can certainly hide the link to non-registered users. You can use either the navbar, or a portal widget, as you suggested.