I would like to display only the teaser view of nodes
One solution would be to use the Rules module.
Add a new rule and set this:

Condition:


Node is of type: News Story
Custom PHP: check display_id == full
User rôle: not admin/editor (so you can still view/edit if you're not anonymous)


Action:


Redirect to the page you want (404 or your news list for example)