How to know if Mac OS X machine is being remotely viewed?

Solution 1:

If your computer is being remotely accessed, it will show a little viewer icon in the menu bar. (Note, I've been using screen sharing since OS X Leopard, and I've never seen the icon noted by de_an777 in his answer.

Go into System Preferences > Shared. Make sure that Screen Sharing and Remote Management (for Apple's Remote Desktop) are both unchecked.

Also, check under Security & Privacy > Firewall and turn the Firewall on. Note the warning. "The firewall will block all sharing services, such as file sharing, screen sharing, iChat Bonjour, and iTunes music sharing. If you want to allow sharing services, click Advanced and deselect the “Block all incoming connections” checkbox."

This will block any incoming screen sharing connection (as well as other services).

To check to make sure that you can't connect to your computer via screen sharing, you can use nmap, a free command line tool for "network discovery and security auditing."

To use it, just type nmap [YOUR IP ADDRESS]

You'll see that nmap reports that the vnc (screen sharing) port is open. After turning off screen sharing and turning on the firewall:

(Note that I've explicitly allowed ssh, printer, and afp sharing in the Firewall.)

I hope this helps you!

Solution 2:

I came here because I noticed my mouse pointer moving around in a distinctly human way without me moving my mouse. I realize this isn't strictly an answer to your question but it may help someone:

It turned out that my office Mac had previously been owned by other people in my office, and was still paired with their Bluetooth mice. Their mice sometimes connected to my machine and then they were waving their mouse around trying to figure out why it wasn't controlling their own computers.

You can unpair mice by going to the mouse settings and clicking the "set up Bluetooth mouse" button, then clicking the "X" next to devices you don't recognize as your own.

Solution 3:

Interesting, I just had the same annoyance. IT logged in, moved my mouse, viewed a few things and I thought, "hang on, there's no indicator at all this is happening..."

The other answers seem correct, however I had an additional thought - this checkbox.

3rd one down "Show when being observed". This was unchecked, presumably from when my machine was originally set up.

My machine is <1 month old, a replacement/upgrade, I have admin rights but still need IT for a range of things. I was/am spewing that this was the default setting.

Solution 4:

Usually, if your mac is being monitored, if will show this image in the top right hand corner near your time:

When that symbol appears, or a symbol that looks very similar to it, like a screen with binoculars in it, it depends on your system , you will be able to tell if you are being monitored. You can also disconnect the viewer like so:

Also, if you have access to your settings with an administrative account you can go to:

System Preferences > Sharing

Make sure Remote Management is Off and that Screen Sharing is Off. If both of these are off then you can not Remote Control/View the Mac over the network through VNC.

I hope that this information helps you keep your privacy safe.

Solution 5:

I guess the problem with the other two answers is that you may not notice the icon in the top right corner of your screen.

What you need is an app that alerts you about any new connections. Little Snitch does this. Whenever a new connection is trying to be made with your computer, little snitch pops up and asks you if you want to allow it or deny once or forever. Really simple and useful app. Can be a bit of a pain at first until you get rules in place for all your applications that access the internet but you'll find after a day or two it won't bother you very often at all.