Screen Sharing is a feature in your Mac that allows you to graphically view and interact with a Mac in a remote location. By logging into your Mac in this way, you will see its desktop appear on your screen just as if you were in front of it, and not only be able to use it, but also copy files to and from it. This makes Screen Sharing perhaps one of the more useful services included in OS X.
Not only does it virtually place you in front of your Mac, but Screen Sharing also makes use of the multiple-account setup in OS X, so one person can be logged into his or her account on the remote Mac, and you can simultaneously screen share into your account to view your desktop and files, without interrupting their workflow.
This setup can be convenient, not only for your Mac at home, but also for those on corporate networks (provided the corporate firewall does not block Screen Sharing). If you have several Macs at work that you have an account on, you can use Screen Sharing to view the desktops of your accounts on those Macs all at the same time on another Mac.
How to set up Screen Sharing
Screen sharing simply requires a local network connection or a broadband internet connection, and then to have Screen Sharing enabled on the computers whos desktops you would like to see remotely:
- Go to the Sharing system preferences.
- Check either Screen Sharing or Remote Management.
- Set the “Allow access for” option to either allow all users, or just a specific user access to this service.
The difference between Screen Sharing and Remote Management is in supported features. Screen Sharing allows any permitted user to log in and interact with the remote desktop, and copy files to and from the system. Remote Management has an Options button that allows you to specify whether a user can start chat sessions, generate reports, open and quit applications, and change settings, etc. These options were initially intended for use with Apple’s Remote Desktop package for managing workgroups, but for most intents and purposes when using the Screen Sharing service, both will be identical.
Once set up, the system will broadcast the Screen Sharing capability via Bonjour networking so you can connect to it from any other Mac on the local network; however, it will not necessarily be available from the Internet (e.g., if you are at a Cafe somewhere and wish to access your home or work computer).
To ensure connectivity from any location on the internet, you can set up port forwarding on your router and then use a dynamic DNS service like noip.com to make connecting easier, but this can be somewhat cumbersome to setup and maintain. Instead, you can use Apple’s iCloud service (even if you do not use iCloud for other purposes), to establish the connection:
- Create an Apple ID and log into the iCloud system preferences on the Mac to be accessed remotely.
- Check the “Back to My Mac” service, and then set the other services according to your needs.
- Log in to iCloud on the Mac you are working on from a remote location.
Establishing a connection
In order to connect remotely to your Mac, as with accessing any remote service you must first ensure the Mac is on and awake. You cannot start up your Mac remotely, and will have to use special services to wake your Mac from sleep modes remotely.
With the Mac on and Screen Sharing configured, you should see it show up in the Sharing section of your Finder’s sidebar for every Mac you configure with the same iCloud account. From here, you can select the Mac, and then click the Share Screen button to launch Apple’s Screen Sharing application and establish a connection:
- Select the remote Mac in your Finder’s sidebar.
- Click the Screen Sharing button.
- Authenticate when prompted, optionally saving the authentication info in your keychain.
When you are connected, you will see the remote Mac’s screen appear in a window on your current Mac, and you should be able to interact with your Mac as if you were in front of it.
Dealing with slow connections
If your Internet connection is slow, then you may see a delay or two in your Screen Sharing session, so be patient if items do not respond to your input right away. At times, you might have to click something or otherwise provide an input, and then wait a few moments, trusting that the input was established, and wait for it to update on your screen.
If you are unsure if an input has been properly issued, you can do an action like opening the Apple menu, again clicking and then waiting for it to reveal on your screen. If this opens and the previous input did not take, then you can try the previous input again.
If the network connection to your Mac is regularly slow, then be sure to turn on adaptive quality instead of full quality in Screen Sharing’s View menu. This will ensure only the changed parts of the image being sent over the network are updated, instead of a stream of full screen re-draws that can bog down a slower network. For most intents and purposes, adaptive quality will give you negligibly different quality from full quality.
Special features in Screen Sharing
Screen sharing supports some convenient features that allow you to get work done quicker and without intruding on others:
- Multiple users
One special feature that Screen Sharing supports, is if someone else is working in his or her account on the remote computer, then when you log in remotely you have the option of either viewing what that person is doing, or logging into your account separately and working with your files and settings, without interrupting that user.
This option will be presented anytime another account is active when you establish your remote connection, and while you can log in while the other user is active, keep in mind this user will see a screen sharing status menu appear, in which he or she can select an option to disconnect the remote connection you have established.
- Copying files and foldersA second option is to copy contents either to or from your remote Mac. All you need for this is to click and drag a file, folder, or selection of items to or from a location in the screen sharing window. Note that since the interaction with the remote system may be delayed by network speeds, you might need to click and drag files to the desired location, and then hold your cursor there until it show the green plus symbol, indicating releasing it will copy the files.
- The Clipboard
In addition to copying files directly, you can use the clipboard to copy contents between systems. If you have a document open on your remote Mac, then you can select some text, or an image, and choose Cut or Copy from the Edit menu of your remote Mac (in the bounds of the Screen Sharing window). Following this, go to the Edit menu on your current Mac, where you should see an option to get clipboard contents, which will load the clipboard from the remote Mac to your current one, allowing you to paste this contents anywhere.
Copying and pasting in this manner can also be done in reverse; however, to make this easier, you can select the option in the Edit menu to use a shared clipboard. This will allow copied contents on either Mac to be synchronized, so you can immediately paste it without having to first use the Send or Get clipboard contents commands.
- Multiple MonitorsIf your remote Mac has multiple monitors attached, then Screen Sharing will offer you options to manage them. You can show them all in the same screen sharing window, but this will make them both relatively small when viewing remotely. This is great for an overview, but not the best for getting any work done. Alternatively, you can choose which monitor to view in Screen Sharing’s View menu, where you can select one or the other.
As with any sharing service, you might be concerned about the security of the remote desktop session. The tunneled connection to your remote Mac using iCloud, and Apple’s authentication to the remote Mac both use encryption and cannot easily be intercepted by a third party. Therefore, if you trust standard file sharing and have your networks secured, then for the most part your connection should be safe.
Beyond the establishment of a secured connection is the fact that if your remote Mac’s screen is on, then anyone who can view the screen will see all of the actions you are taking. Unfortunately, you cannot sleep or otherwise mask the remote Mac’s display to hide your work, since the display will just wake up when you provide additional input. Therefore be sure this setup is secured before doing any work that you might wish to be private.
When you are finished with your remote session, if you close the Screen Sharing window then you will keep the remote Mac as-is, so be sure to log out of the remote system using its Apple menu, if you wish to secure your account.