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.
There is another, easy way for screen sharing in OS X: You can use Messages (formerly known as iChat) to connect with other Mac users and share your screen with them, or ask to access their screens. You only need to know their Apple ID (email address). It seems there are some minor restrictions in this kind of screen sharing: I think you cannot share the clipboard content, but you can use your keyboard to enter text on the remote Mac, you can use the mouse or trackpad to point and click, and you always have an audio connection. If you want to share files, you can drag them into a text chat window and send them.
True, except this requires users on both ends to submit and accept the screen sharing request. This is great for helping someone fix a problem, but will not be the best for establishing your own access to a remote system (e.g., accessing your office computer from home).
Regarding Screen Sharing through Messages/iChat, it not only works with iMessages contacts (i.e., the “regular” ones linked through their Apple IDs). I have confirmed that it works flawlessly with Google Talk contacts, and it’s likely that it will also work with the other kinds (AIM, Yahoo, and Jabber-based services).
As Topher said, that’s priceless for remote support, (though not for accessing your own Mac without assistance).
An extra tip if you are frequently connecting to another Mac using the Back to My Mac service:
Use the Connect to Server command in the Finder’s Go menu (or Command-K for short). In the panel, add the Macs you want frequent access to the Favorite Servers list like this:
where name-of-the-Mac is of course the name of the Mac (usually something along the lines of “Your Name’s MacBook Pro”) and ######## is your iCloud account number, which you can find by typing this into that Mac’s terminal:
(it’s the number you get at the very end. Ctrl-C will return you to the command line.)
BTW, you can use the same address (name-of-the-Mac.########.members.btmm.icloud.com) to log into your Mac via ssh.
I’ve never gotten this to work properly.
I’ve used ‘dns-sd -E’ to get my membership number for iCloud, but it doesn’t seem that anything is even at the whole FQDN that would address to my home machine:
Doing a ‘dig any dash..members.btmm.icloud.com.’ returns NXDOMAIN.
Tracing further up the DNS tree, the NXDOMAIN seems to be for the ‘members.btmm.icloud.com.’ part, and ‘btmm.icloud.com.’ doesn’t even appear to have any NS records associated with it.
I’ll agree that the whole .members.btmm.icloud.com thing is kind of weird. Even while I’m connected to my parents’ Mac I can’t do almost anything with it… ping, traceroute, etc, nothing works.
The only things that I have been able to get to work are precisely Screen Sharing and ssh, as I described above.
For ssh it works directly (ssh my-username@name-of-the-Mac.########.members.btmm.icloud.com), but I configured an entry in the .ssh/config file for ease of use.
Thanks for the refresher on Screen Sharing. Like many of your other articles this one is going right into my reference file “cabinet.” I set up my own filing system many years ago before all these fancy note-taking apps came on the scene. No proprietary application formats to worry about reaching a premature EOL. My files are all in SimpleText (txt), TextEdit (rtf), web archives and PDF format. I can open a file created 15 years ago as easily as one saved today. I recently switched from saving articles in web archive format to using the Print dialog to save them as PDFs.
Is there a way use a local printer to print from a remote computer connected through screen sharing? I know it’s possible with Windows RDP but I can’t see how in OS X.
Thanks for any ideas.
Share your printer in the Sharing system preferences, and then enable Back To My Mac on your system. From here, you should be able to access the shared printer on any of your remote Macs anywhere on the internet, that are configured with the same iCloud account. Note that you do not have to do this through Back To My Mac if you are on the same local network as your Mac with the shared printer.
Thank you for this suggestion. Unfortunately, computers that access this “server” through screen sharing are not on the same iCloud account nor on the local network. I was hoping to find in OS X something similar to:
You can use various desktop screen sharing tools such as WebEx, GoMeetNow, Gotomeeting, RHUB web conferencing servers etc. for sharing screens between MAC and Windows computers.