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Mavericks remote concurrency

OS X Mavericks concurrent remote user access from Linux


To do concurrent remote desktop access on a single OS X machine from multiple Linux/Windows desktops in a way that one session does not interfere with another user's session & performance should be acceptable to use.


OS X's built-in "Screen Sharing" utility:

VNC protocol serves as the base for remote user access on OS X, just like it's RDP on Windows. Starting from OS X Lion+, we know that OS X ships with a built-in utility called "Screen Sharing" to offer remote user login. There are number of articles explaining how to do that and what VNC clients you could use. However, that works great when it is accessing the server from another Mac. Due to its closed nature, OS X's screen sharing doesn't work well with VNC clients available for Linux.

Problem: Issues that were faced with the built-in sharing utility when accessing from Linux Clients are:

  • Poor performance - it takes ages to just see the cursor/mouse pointer move. It's practically unusable with the default setup
  • Unable to update resolution - when we change resolution from the client window, it corrupts the session's display and takes 5-10 mins to repair itself

Solution: Use an alternative stand-alone VNC Server

  • Download Real VNC and install it on the host OS X machine. It is to be noted that this method requires the Mac to be connected to a display. Once installed RealVNC server would run in "Service Mode" - however, the mode won't be useful for concurrent user access because it shares the main display's screen for all users.
  • Assume that there are 3 users on the host OS X: user1 (who uses the Mac on it's native display), user2 & user3 connects remotely from Linux desktops
  • Since we are to run RealVNC in user-mode, it means that if user2 has to remotely login to his account named "user2" on the host machine, he has to first login to user2 account on host machine locally - then start RealVNC server in user-mode and then use switch-user feature to go back to native user account "user1". Now, user2 could remote login to his user2 account until the host system is up & running (and until user2 account is not logged out)
  • There is a gotcha: by default - RealVNC server in user-mode will kill itself on fast user-switching. To prevent the default behavior, go to RealVNC server options -> Expert -> set StopUserModeOnSwitchOut to False - refer screenshot below

          user Mode switch

  Now, user1 could continue his work on native display and user2 could access his account through a VNC client at acceptable speed & quality. The same process has to be repeated for a number of other user accounts as required.

 Yes - it's not an easy job starting up VNC server in user-mode for many number of users manually. In that case, leaving the OS X host running 24x7 could be a viable solution. I would be happy to hear if anyone has a better solution to share.


Hi, you need to run the application: "VNC Server (User Mode)" -- not the "VNC Server" application. It is packaged along with "RealVNC" & available at Applications/RealVNC/Advanced/VNC Server (User Mode)