How to Remotely Access Your Mac’s Screen

Several readers have started writing in to ask whether they can access their Mac screen from their work computers, which tend to be Windows-based PCs. One of the great things about Mac OS X is that it has a screen sharing feature built-in, which you can turn on with just a few mouse clicks. As long as your Mac is turned on and connected to the Internet, you can view and manipulate your screen just like you were at home. Follow this tutorial to access your Mac from your work computer — or any other.

When you want to allow other computers to access your Mac’s screen, you are turning on a feature that Apple calls “Screen Sharing.” When you share your screen, one other computer can access and control your Mac’s screen at a time. To turn on Screen Sharing, follow these steps:

Open System Preferences.Select the Sharing preference.Check the box next to Screen Sharing to turn it on.In the lower right portion of the window, you can see the statement, “Allow access for.” This allows you to select whether you want to allow all users of this computer to access it remotely or only certain users. Now, if you were only going to access your Mac from another Mac on your local network, you could stop here. However, if you plan to access your Mac from another network, you need to perform this next step:
Above this section, there is a button called Computer Settings. Click this button and then check the box that reads, VNC viewers may control screen with password.” Finally, type a password that you want to use to access your computer remotely (make it a good one) and then press OK.

That’s all you need to do on your Mac’s end to make your screen accessible to the outside world. Depending on what kind of computer you have elsewhere, however, you may need some additional software to access your Mac…

Turning on Screen Sharing is a potential security risk, as a hacker may be able to gain access to your machine. Please make sure you have strong passwords and are willing to assume this risk.

In the previous section, we turned on Mac OS X’s built-in Screen Sharing technology and then added remote access via the VNC protocol. Mac computers have a built-in VNC viewer, too, so if you’re using a Mac at your office or elsewhere to view your Mac at home, you don’t need any extra software. To access your home computer from a Mac, do this:

From the Finder, select the Go menu and then select Connect to Server.In the “Server Address” field, type “vnc://” (instead of, say, “http://”) and then the IP address of your home computer.Now click “Connect” and wait for your remote Mac to respond and ask you for the VNC password (that you previously set). Enter the password, and presto! You will see the contents of your home Mac in a window on your remote Mac.

If you have a Windows machine, however, you will need to download a VNC viewer. Microsoft’s own “Remote Desktop Connection” application, which comes with Windows, is not what you need to use. Instead, there are some very nice (and free!) VNC viewiers available, such as RealVNC Free Edition and UltraVNC.

Once you install one of these applications, the process is basically the same as on a Mac: open up the VNC viewer, enter the IP address of your home Mac, and enter the VNC password when prompted. You can then view and control the contents of your Mac from a PC!

On Mac OS X, Screen Sharing opens your Mac's screen in a new window.

Out of all of this, the toughest part is dealing with your home Mac’s IP address and routing the VNC request. When you have broadband Internet, whether it be wireless, cable, or DSL, you may have a dynamic IP address, which means that it can change from time to time. That doesn’t do you any good, since you’d ideally like to have one IP address that you can use today or a year from now to access your home Mac. If you have a static IP address, it never changes, so you don’t need to worry about this.

First of all, if you do not know how to find your external IP address (especially if you’re behind a wired/wireless router), simply go to whatismyipaddress.com from your home Mac. It will tell you your external IP address, which is what you need to type in to connect from your remote computer.

One solution — if you’re only using Macs locally and remotely — is to use use Apple’s MobileMe service and turn on the “Back to My Mac” feature, which tracks the IP addresses of all your Macs so that you can easily connect to them remotely. This setup is pretty easy, but MobileMe’s not the cheapest solution out there.

Another (free!) solution is to use DynDNS’s dynamic routing service. You go to www.dyndns.org, create an account, select a routing address (such as myhomecomputer.dyndns.org), and install the DynDNS Updater utility on your Mac. This utility periodically checks to see if your external IP address has changed. If it has, it alerts DynDNS. All you have to do is tell the VNC viewer to connect toyour DynDNS routing address (such as myhomecomputer.dyndns.org), and then DynDNS will route that request to your home computer. DynDNS has a great guide on setting this up on a Mac.

There is one final consideration: opening up a port on your router so that VNC can get a connection started. This is beyond the scope of this article, but basically, if you feel you’re doing everything right and you still can’t connect to your home computer remotely, you may need to open up TCP port 5900 on your firewall and route the port to your home Mac’s local IP address. If you’re using an AirPort router, you can do this through the AirPort Utility in your Utilities folder.

This guide is not intended to be an exhaustive guide for all solving every remote access issue. Setting this feature up may be easy for you, or it may prove daunting. There’s a reason why services such as GoToMyPC exist: for a price, they make the process painless, as their software and servers take care of all this work for you. But, if you’re willing to spend some time setting this up, you’ll have a way to access your Mac — for free — from anywhere in the world.

Tagged as: apple, mac, Screen Sharing, VNC