Mac® Security Bible

11.2. Controlling Another Computer Remotely

From the comfort of your Mac (even if it's a laptop on a park bench), you can view the screen of another computer and control it using your own keyboard and mouse as though you were sitting right in front of it. The reverse is also true, given the appropriate sharing and firewall settings — someone can view your Mac's screen and control it from another computer. Screen sharing, as this process is called, is extremely powerful, and for that reason, you should take particular care to ensure that no one can intercept your credentials or the actual screen data while it's in transit. Although there are several different ways to go about sharing a screen, the specific precautions you must take are somewhat different for each.

11.2.1. Using Mac OS X Screen Sharing

Screen sharing requires two software components: a server running on the remote computer, which makes its screen available to others, and a client running on the local computer, which lets you connect to and control the screen of the server. The most widely used protocol for sharing screens is VNC (Virtual Network Computing), and in general, any client or server based on the VNC standard can communicate with any other VNC system, regardless of platform or brand.

Every Mac running Mac OS X 10.3 Panther or later has built-in client software for Apple Remote Desktop, a remote administration tool described just ahead, which uses VNC for screen sharing. Because (in a confusing twist of ...