OS X Sharing Preferences (Part Two)

By Graham K. Rogers


The Sharing Preferences panel in System Preferences of OS X has eleven ways in which we can link to other devices to increase the usefulness of our computers. I have split these in two and this week begin with Remote Login.

This works with the Finder and a user can log in to the computer from another on the network. There are overlaps here with other types of sharing. The Finder "Go" menu uses several ways to connect quickly to folders on the users' computer or to remote devices using "Connect to Server" (Command + K).

This reveals a panel in which we can browse for another computer or enter an IP number with the prefix of AFP 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 works in conjunction with the Apple program, Remote Desktop. This helps those running a network of Macs, such as a school Lab, to control the functions of those computers from a master computer. A number of these functions have now been superseded by the Screen Sharing function which was outlined last week.

events sharing Remote Apple Events is not a way to track announcements from Steve Jobs about new products (doubtless there will be some soon), but, according to the preference pane, Allows applications on other Macs to send Apple Events to the user's computer.

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.

xgrid sharing When the feature called Xgrid sharing first appeared the potential was clear to many people. In one click, according to Apple, this would turn an "ad hoc group" of Mac systems into a supercomputer. It is slightly more complex than that, but I know someone in Singapore who created a cluster with three Mac minis.

There had already been distributed computing across the internet: for example the SETI project. Last week, in Nature, it was reported that another such project involving 30,000 computers had successfully simulated part of a complex protein structure.

Apple helped build the multi-computer system at Virginia Tech, originally with some 1,100 G5 Macs, but now using 324 8-core, 2.8GHz Macs which will have a theoretical speed of 29 teraflops. The idea of setting up such a multi-computer system (albeit somewhat smaller) on a home network had been unreachable until Xgrid Sharing.

It links computers, turning them into a cluster and distributes tasks to the processors in a way that calculations are combined: computer teamwork. Turning this part of Sharing on will allow the computers to share resources. What it still requires, however, is someone with the skills to write the software to control the tasking.

Internet Sharing can be useful if a home has limited networking resources: for example a router with a single port, or a computer with no wifi. Input to a computer can be from one of four sources: Airport (wifi), Bluetooth, Ethernet or (oddly) Firewire, previously an OUTPUT method. That incoming signal can be routed to another computer, via Ethernet or Airport. Input and output methods must be different on the master computer.

internet sharing internet sharing

This takes advantage of other Sharing methods when it is possibe to connect directly with an Ethernet cable and OS X will allocate IP numbers. Similarly, using the Airport menu, we can create a computer-to-computer network easily. Doing this at the same time that a wifi network is running, however, will disconnect the computer from the Internet.

airport network

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. This is also possible with an incoming connection via a Bluetooth mobile phone (e.g. Bluetooth in, Ethernet out) although there are speed penalties.

Bluetooth Sharing covers the downloading or uploading of files from devices equipped with this feature. There are several options about actions to be taken (Ask, Accept, Never) and check-boxes that require devices be paired. There are also options for folders to receive files and folders that others may browse.

I shall be continuing the extended look at System preferences in the future.

See also

  • Part one of the look at Sharing, and
  • other articles on System Preferences and information for new users (and old ones too).

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