I don\'t know why \"logged in users can do anything\" means Jenkins will happily allow non-authenticated users to view project details and access artifacts... Regardless, I nee
This can be done with the Role-Strategy plugin.
Install the plugin, add a new group called "Anonymous" and uncheck everything. Then you want to add another group called "authenticated" and check everything. Add your existing users to this group. Jenkins will immediately prompt you for a login this way.