public and private controller

[eluser]Mutsop[/eluser]
Hi,

I have a few controllers which should only be accessed using by logged users.
Now I thought I needed only to set the check (if user is logged in) in the index function of the controller.

Apparently that doesn't work when you try to input the url directly of the other functions.

So i've been reading throughout the web and found out there would be a possibility to use some public or private controller?

Is this correct? and how?

If so, what about if some functions should be able to be accessed and some not in the same controller?