Occasionally when I remotely control a client computer using Apple Remote Desktop it will visually display the remote user’s desktop as a blacked-out screen.
When I experience this and I move the mouse pointer around the blacked-out screen, the remote user looking at physical screen will confirm the mouse movement. For obvious reasons, this is not helpful when assisting the user with remote support.
One possible workaround that has worked on some occasions (but not always) is to restart the Apple Remote Desktop Client service.
There are two ways to restart the Apple Remote Desktop Client service, by means of the graphical interface, or the command line.
To restart the Apple Remote Desktop Client service using the graphical interface, simply ask the remote user to go to:
> System Preferences > Sharing and Stop/Start the service called Remote Management.
However, it should be noted that the remote user on the remote computer will need to be an Administrator, or they will need to know an Administrator’s username and password in order to Stop/Start the Remote Management service.
If the remote user is a non-admin, and you are unable to provide them with Administrator details due to policy, then you may be able to remotely restart the Apple Remote Desktop Client service using SSH if already enabled.
To check if SSH is enabled, ask the remote user to navigate to:
> System Preferences > Sharing and confirm if the Remote Login service is enabled or ticked.
If Remote Login (SSH) is enabled, then follow the commands below to remotely login into the computer using SSH which will then allow to you remotely restart the Apple Remote Desktop Client.
Note: In general, you will only be able to SSH to a remote computer if you are local to it (as in on the same network) or you have a VPN connection to that network. It is unlikely that you would be able to SSH to the remote computer from the public-side (WAN) of the network due to security implications.
1. Open the application Terminal (Applications > Utilities).
2. Connect to the client computer using SSH by typing ssh <admin-username>@<client-computer-ip-address> (e.g. email@example.com) and, when prompted, authenticate using the password relevant to that admin user account defined before the @ symbol.
3. When you have successfully SSH’d to the remote computer, enter the following command below to restart the Apple Remote Desktop client software.
sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -restart –agent
4. To disconnect your SSH remote session to the remote computer simply type exit follow by the return key.
If the above does not work for you, then you could try remotely updating the Apple Remote Desktop Client software using your Apple Remote Desktop Admin software (in ARD Admin software select remote computer, click the menu Manage > Upgrade Client Software).
Alternatively, rebooting the computer should also resolve the issue but may not be practical if the remote computer is a server.