One of the many new features in Leopard is its screen-sharing capabilities. Some screen-sharing capabilities have been available in Mac OS X since Apple released Apple Remote Desktop in 2001. Apple Remote Desktop, however, was always intended for larger organizations that needed to be able to remotely manage or monitor large numbers of Macs.
The Apple Remote Desktop client, which was built into Panther and Tiger, did offer the additional capability to remotely control a Mac using the open VNC standard, although no VNC viewer was included with either Mac OS X release.
Leopard brings screen sharing to every Mac user and does so in a series of ways that make it an easy-to-use extension of the Mac experience.
Neither a VNC client nor Apple Remote Desktop is required (although the underlying technology is based on VNC), and Leopard makes finding and connecting to Macs on your home or small office network incredibly simple. That alone would be news, but Leopard also lets you initiate a screen sharing session with a remote user from within iChat.
And if you’re a .Mac subscriber, you can easily connect to your Mac from any Internet connected computer in the world.
Enabling Screen Sharing
The first step of using screen sharing is to enable and configure it in System Preferences.
Screen sharing is located inside the Sharing pane (see Figure 1).
Figure 1 Setting up screen sharing
Enabling the feature is as simple as checking the On box next to Screen Sharing in the Service list. That is really all that needs to be done.
By default, once enabled, Screen Sharing is available to anyone who has a user account on your computer (including the Guest user if you have enabled the Guest user account). Enabling the Guest user and allowing all users to connect to your Mac makes your Mac very vulnerable as anyone who can locate it can connect and use it as though they were sitting in front of it.
If you do allow all users access and leave the Guest user enabled, you should ensure that your Mac is set to require a password to wake the computer from sleep or screen saver and enable the screensaver (using the Security and Desktop & Screen Saver panes in System Preferences respectively) as this will help limit access to your Mac. Even if you limit access to your Mac, this is advisable for extra protection, particularly if you will be connecting remotely over the Internet or using screen sharing with the .Mac Back to My Mac feature.
If you want to restrict access to certain users you can select "Only these users:" instead of the default "All users" radio button in the "Allow access for:" section.
You can then use the add (plus sign) button to select the users and/or groups that will be allowed to connect using screen sharing. You can even create a new accounts on the fly using the add user dialog sheet.
If you want to remove a user or group from this list, simply select the user/group and click the remove (minus sign) button.
You can also use the Computer Settings button to make access available to people beyond those who have user accounts. This button displays a dialog sheet with options to allow users to request permission to use the computer or to allow access via VNC.
VNC access makes screen sharing available to users of pre-Leopard Macs as well as PCs running Windows or Unix/Linux provided they have a VNC viewer installed.
If you enable VNC access, you’ll also need to enter a VNC password that will be required to connect to your computer. VNC viewers rely solely on this password to connect to your computer, instead of on a combination of user accounts and passwords. It also doesn’t support data encryption like screen sharing does, making VNC access much less secure than screen sharing from another Leopard Mac (a major concern if you use VNC access over an Internet connection or open wireless network).