By Graham K. Rogers

There were many changes to System Preferences with the recent update of Apple's OS X to version 10.8, Mountain Lion. Sharing preferences controls the way a user's computer may link with others on a local network or outside. The panel looks almost the same when compared with 10.7, but there are certain important changes.

Sharing Preferences retains the same interface with the update to OS X 10.8, but has had two of its previous features removed: Web Sharing and XGrid Sharing. All of these preferences work with Security (and other) Preferences to enable specific connection methods to be used and to activate the necessary ports when needed: for example, when we join networks and link to devices, like printers or scanners. There are now only ten different ways to share in the preference panel.

When the Sharing panel is opened the panel is split into three sections. At the top there is an editable panel with the name of the computer entered. This name is for any connections on a local network. The name may be changed in the panel available or by using the Edit button which reveals a small panel for the purpose. Also on the panel is a checkbox: Use dynamic global hostname. If this is used, the panel expands to reveal spaces for more data: Hostname, User, and Password. There is a further checkbox marked, Advertise services using this domain using Bonjour (Zero Configuration Networking).

The main panel (below the computer name) is in two parts with first a list of the ways connections and data may be shared to the left. Each has a checkbox and then the name of the service alongside. The main display has information about any specific highlighted service and (depending on the type of sharing) may have additional panels to indicate connection information.

DVD or CD Sharing

Screen Sharing

Connections are made by clicking on the computer name if it can be seen in the Finder panel (or using the IP number of the computer with a VNC prefix (e.g. vnc://192.168.10.55) in the "Go" menu, Connect to Server), I can work on the target computer as if it were my own: exactly as if I am sitting in front of that computer.

Some Finder preference settings may also need to be checked in the Sidebar section, so that Shared devices are more easily visible.

The purpose here is to assist another user by working on the remote computer, for demonstration or diagnosis. Anyone who has tried to advise someone on the telephone about what to move, what to open, what to trash, will realize how hampered we are by the lack of visual input. Moving the cursor for the other user, opening the correct panels, is more effective.

This preference does not allow files to be dragged from the target screen to the desktop or vice versa. However, it is possible to send the contents of the Clipboard. That data could be pasted into a file on the remote computer (by the demonstrator) and displayed. An example might be an image of settings to allow comparison by the second user.

Screen Sharing connects to the active user's screen, which means it could be abused. Using the button to the right of the main panel, Computer Settings, reveals a panel with two checkboxes: Anyone may request permission to control the screen; and VNC viewers may control the screen with password (a box alongside is provided to enter a password).

In the lower section of the information panel a user may specify either All or specific users to be granted access. Users can be added or removed using + and - icons beneath the user-list panel. This reveals a panel with account names on the computer shown, but there is also access to the Address Book, so any user may be added this way. If the name of the person to be granted access is not shown via those resources, a further button allows a "New Person" to be added. An example might be a technician from a local internet carrier contacted for trouble-shooting. I would advice prudence before granting such access.

If a New Person is to be added, I small panel appears with User Name, Password and Verify boxes. If such access is granted the name should be removed as soon as possible afterwards.

To stop the connection we use either the Screen Sharing menu and Quit, or "Disconnect" in the Finder menu. See also Remote Management (below).

File Sharing

An Options button brings up a panel with the types of connection that are available: AFP and SMB. These are made active using checkboxes. There is a warning concerning password use with SMB. Activating this for any account needs the password for that specific account. There is a further warning about insecure storing of Windows users' account passwords on the Mac.

The main panel lists the users and the type of access (Read & Write, Read Only Write Only). It is possible to add new folders, new users and new groups using the + and - icons below.

Printer Sharing

Printer Sharing allows users to have a single printer, for example attached to my iMac using USB and to print via the LAN. The Printer Sharing preference was turned on for the iMac. A button near the top of the pane allows direct access to the Print & Scan preferences panel.

Two data panels list any printers that are connected and they may be added using a checkbox, then used. The second panel lists those who are allowed access. In my case, Everyone is shown, but I may add a specific account or user (or other) using the panel revealed by pressing the + icon.

Scanner Sharing

Remote Login

We may then browse for another computer or enter an IP number with the prefix of AFP (e.g. afp://192.168.1.2/) or SMB for Windows. SSH with the user name may also be used. With recent changes to the operating system, it is now easier to use "Shared Devices" in the Finder menu.

Remote Management

When Remote Management is first selected, a panel is opened automatically (it may also be seen by pressing the Options button) that allows a user to select certain functions. This supersedes Screen Sharing and a note appears if Screen Sharing is selected to this effect.

A button in the top half of the information screen is marked Computer Settings. This reveals a panel with several options, including Screen sharing items. There are three checkboxes: for display of an icon in the menubar; Anyone may request permission to control screen; and VNC viewers may control screen with password (a box is alongside for this). Four boxes allow entering of computer information for display in a System Overview report.

Like Screen Sharing, in the lower section of the information panel a user may select to allow either all or specific users to be granted access. Users can be added or removed using + and - icons beneath the user-list panel.

Remote Apple Events

Events can be initiated by programs or Apple Scripts and are a way to use the resources of one computer from another, such as shutting down or opening a file. A simple example from the past is the command to print which now has a specific Sharing panel. This type of feature would be more common in an office where several Macs are used and the sharing of data and resources is integrated into operations.

A recently modified Wikipedia page on Remote Events may provide some useful background.

Internet Sharing

That incoming signal can be routed to another computer -- as Output -- via a port that is different from Input.

• For Wi-Fi input, the output may only be via Ethernet or Firewire.

• Ethernet Input to Ethernet, FireWire and Wifi. If Ethernet is selected there is a strong warning about possible termination of service (by the ISP). FireWire and Wi-Fi may both be selected at the same time.

• Bluetooth DUN to Ethernet, FireWire and Wi-Fi (all three together are possible).

• FireWire to Ethernet, Firewire and Wi-Fi. If the FireWire box is selected, another warning panel about ISP termination of service appears. It is possible to select Ethernet and Wi-Fi together.

When any Wi-Fi output is selected a Button for Options becomes live and a panel opens to allow configuration of the network: Name, Channel (from 1 - 11), and Security (None, WPA2 Personal).

When the Internet Sharing checkbox is selected a panel warns users of possible settings changes.

A possible scenario is that a computer with no wifi can be connected to a machine that has a wifi antenna (data in) using a direct Ethernet cable. Also, in the past, when I was testing a computer with wifi, but had no spare cable in the room I was using, I could connect my computer to the router with an Ethernet cable and then create a wifi network on that Mac that the second computer could link to.

Bluetooth Sharing

There are two main parts to the panel. The top section deals with file transfers and has a button with options about actions to be taken (Ask, Accept and Save, Accept and Open, Never). A second button enables the selection of a folder for transfers. The default folder is Downloads, but there is an option for Other, allowing a user to select any suitable location.

The other part of the main panel is for users to decide on actions when Bluetooth devices browse the computer. A button has the default, Ask What to Do with options of Always Allow and Never Allow. A second button indicates the folder that such browsing devices may access. The default is Public (see File Sharing above) with an Option for Other, allowing a user to select any suitable location.

A button at the bottom of the panel links to the Bluetooth preferences panel.

Notes

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.