Thanks @julian. I might investigate whether I can achieve what I'm aiming for with a plugin in the meantime.

I've just set up NodeBB for a private forum for a small gaming community. We have quite a lot of info in shared Google docs which I'd like to be able to put on the new forum, but I don't want it all to be publicly visible to the whole world.

Any plans to allow us to create private categories which can only be viewed by logged-in users? Or alternatively, a simple toggle switch to make an entire forum private would be good.

In addition to this, I guess we would also have to be able to lock down user registrations in some way (so that new users require approval before they can log in).