Limit access to posts/pages by user roles

I’m looking for a way to protect content by user roles.

Example:

you have to be registered to view posts (frontend).

If a user is a subscriber he can read post 1, 2 and 3, but if the user is a contributor he can view post 1,2,3 and 4,5,6…

does anyone know how I can do this?

Although I haven’t used this personally you are probably looking at a plugin like this

Seems to provide all the functionality you have requested above.