screen sharing permissions?

Yes, I know I can restrict screen sharing to specified users. But the new Mac operating systems allow screen sharing of either the screen currently being displayed on the machine monitor OR a screen specifically in the account of the remote user doing the screen sharing. If, for example, Joe is sitting at the computer, using the screen in his account, and Jane wants to log into the machine and get her own screen in her account, what prevents Jane from choosing to look at Joe's screen instead? Both possibilities seem to be allowed, but I frankly don't understand why the second possibility is allowed.

That is, when I launch screen sharing, I am asked "How would you like to connect?" "Share the display", or "Log in as yourself". It would seem that just the fact that I have an account on that computer would, in the first option, allow me to look at the active screen of someone in their own account instead. Joe might not be happy that Jane is looking at his screen while he is using it. How do I restrict just MY screen to specified users, and let others look at their own?

I have never shared a screen and needed to restrict what users see. I am not sure you can but I did find a link for El Capitan on screen sharing.

https://support.apple.com/kb/PH21804?locale=en_US&viewlocale=en_US

Lisa

OK, I'm unable to check this out for a while, but here's what I think MIGHT be going on.

If I'm sitting at the computer, and I uncheck "Screen Sharing" in Preferences, my screen that I see will not be shared, unless perhaps someone else is logging in remotely as me.

If, however, that remote person is logging in as someone else, they can only get their own screen (if they are using a modern OS), and not be offered to see my screen. Getting your own screen may not be defined as "screen sharing". You're computer sharing, but you aren't screen sharing.

That is, if I'm using a recent OS, and I uncheck the screen sharing box, people connecting to my computer will simply not be offered a chance to look over my shoulder at my screen. They will, however, be offered their own screen on their own account. If the screen sharing box is checked, they can choose one or the other.

Is that what is going on here?

I believe you are correct from what I am reading and understanding. Screen sharing is used for things like training someone or sharing and looking at a presentation. You expect the person sharing your screen to see what you want them to see on your desktop.

Remotely accessing a computer and logging on as another user is very different. The mac will create a separate desktop for them with only their documents and customizations available. They will not have access to anyone else's desktop, documents, etc.

Lisa

Even if screen sharing is turned on someone would have to know your username and password to see your screen / files (assuming your files are stored somewhere inside your user folder. Just make sure that you have a strong login password. Couple that with a strong network password and you should be OK.

Actually, screen sharing (as in "not remote login") **cannot** be accomplished without **explicit** permission from the user who's screen is to be shared, each and every time it is requested. Screen sharing ≠ remote login, so the user who's screen is to be shared must be present and authorize the sharing.

Thank you. I think that is correct. If I choose to "Share the Display" of someone else, it will ask me to log in with their password. I'm not sure why that wasn't obvious to me before. I thought I was able to share that display without logging in, but it appears not. I had been playing with other VNC applications that didn't require me to do this, and I probably got confused. It all makes sense now.