I've been searching for a solution to this issue but have been unable to find one.
I'm setting up a Multisite installation where I want all client sites to be public, but users that are given logins should only be able to log in to sites that they are associated with.
For instance, when a user logs in to their site and then navigates to another site in the network, it should not show the navigation bar at the top of the page, nor should it say "Logged in as [username]" in the comments section and allow them to post comments as that user.
There is a case that users might have logins for multiple sites in the network. In this case the single login should be shared among just the sites they are associated with.
Essentially each site is separate, but can have shared users in certain cases.
Are there any plugins that provide this or similar functionality? The "More Privacy Options" and "Network Privacy" plugins don't do what I need.