Use one keyboard & mouse to control three computers with Synergy
I have a MacBook-Pro connected to a 24″ Cinema Display with extended desktop and a PC connected to a 20″ widescreen monitor (which I turn on mainly to warm the room up) in my study. It’s not a very big space and I didn’t want to have two keyboards and mice on my desk so I was considering getting a KVM until I discovered Synergy.
Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It’s intended for users with multiple computers on their desk since each system uses its own monitor(s).
Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy also merges the clipboards of all the systems into one, allowing cut-and-paste between systems…
Sounds great right?
Well it is, once you’ve figured out how to set it up. To be honest Synergys configuration page is so confusing I nearly gave up entirely until I found SynergyKM, a GUI for MacOSX.
I’m going to take you through an example of how Synergy can be used. In this example we have an iMac, which our keyboard and mouse are connected to, a MacBook-Pro situated to the left of the iMac and a PC situated to the right.
iMac
The iMac is going to be our server (the computer that our keyboard and mouse are connected to). Through trial and error with synergy I’ve found that it works best if you set the server to have a static IP address.
On MacOSX we have the option to set our ethernet to Using DHCP with manual address, this is handy because, as the option would suggest, all we have to enter is the IP address and the rest of our network configuration is set through DHCP by our router, so lets do this first.

Go to System Preferences > Ethernet
For this example we are setting the iMac IP address to be 192.168.0.10.
SynergyKM software
Download and install the SynergyKM software onto the iMac. At the end of the install you’ll be presented with the option to Configure SynergyKM, this will load the SynergyKM control panel. If you miss this option you can find the control panel through System Preferences > SynergyKM.
Once the control panel is open match the settings in the screenshot below:

We set the iMac to Share my keyboard and mouse
Then select the Server Configuration tab. At this stage you should only have one machine (iMac). We need to add our additional two machines, MacBook-Pro and PC.
Click the + twice and enter the name of each machine. You can now drag these machines to be laid out in relation to the iMac. In this example, MacBook-Pro to the left and PC to the right.

The name of each machine is there actual hostname, this is set through System Preference > Sharing on a Mac and System Properties > Computer Name on a PC
Finally go back to General tab and make sure Synergy is turned on.
MacBook-Pro
Like with the iMac we need to install the SynergyKM software on the MacBook-Pro. Once you get to the SynergyKM control panel match the settings on the screenshot below:

We set the MacBook-Pro to Connect to a shared keyboard and mouse
Then select the Client Configuration tab. Connecting the MacBook-Pro (client) to our iMac (server) is simple, we just enter the IP address for the iMac that we set earlier (192.168.0.10).

If you click Apply Now you should be able to move your mouse courser off of the left side of your iMac and onto the desktop of the MacBook-Pro
PC
For the PC we need to download and install the SynergyInstaller-1.3.1.exe. Once installed run the Synergy application and match the settings from the screenshot below:

Again we enter our iMac (Server) IP address, 192.168.0.10
Click the AutoStart… under Options.

These options will lead you to believe Synergy can be set to start when your computer starts. It lies!
Install the When You Log In auto start utility. In my experience if you install the When Computer Starts utility Synergy will never start automatically.
If you’ve used Synergy before and know how to make it start when the computer starts I’d be interested in hearing how, so please leave a comment, however I’ve always been under the impression that no program can run prior to a Ctrl-Alt-Del and Login for security reasons?
Installing the When You Log In auto start utility does however cause us a small problem which I’ll cover in a moment. However at this stage if you click Start you should be able to move your mouse cursor off of the right side of your iMac and onto the desktop of the PC.
PC gotacha
There always one isn’t there? Synergy works fine on PC, but only once you’ve logged in and Synergy has started up, and what would we need to log in? …a keyboard and mouse, which makes this whole setup rather pointless. To work around this we need to enable automatic logon for the PC.
To achieve this go to Start > Run and enter control userpasswords2

Select the User Name you want to be have automatically login and untick the Users must enter a user name and password to use this computer
Click Apply.
Now when you power up the PC it will automatically logon under that account, Synergy will run at start up and you’ll be able to control it using the keyboard and mouse connected to your iMac.
There may obviously be occasions when you don’t want the PC to automatically logon. In this case you would need to set the PC up as the server with the iMac and MacBook-Pro as clients. You should be able to figure out how to do this from these instructions, the process is pretty much the same, and I’m guessing you’ll need to set the iMac and MacBook-Pro to automatically logon instead.
Conclusion
So that’s it. Hopefully from this example you can apply Synergy to your own computer layout and get rid of all the cables need for that KVM or that extra keyboard and mouse on your desk.
Additionally you’re not limited to only connecting three computers with Synergy, you can have as many as you like, knock yourself out!
If you’ve found this tutorial useful please leave a comment and let me know, I’d be interested to hear from you. Enjoy!

















12 Comments
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Stanton 22nd, January 2010 at 12:23 pm
Oh Synergy, how I love thee!
As you've said, the setup can be a rather confusing affair but it works great. I have it controlling my 3 screen PC/Mac desktop right now :)
Paul Burke 24th, January 2010 at 9:03 pm
I knew about synergy, had a play but got lost in the setup; will have another go when I get a chance. - My desk thanks you for posting.
John Tempest 6th, March 2010 at 1:09 pm
Do I have to install synergy on all the workgroup computers
regards John
Ryan Taylor 6th, March 2010 at 7:52 pm
@John That's right. You have to have the Synergy client installed on all the machine you want to control.
John Tempest 7th, March 2010 at 8:36 am
I have installed synergy on two computers and followed the instructions on this web site.I get the error message failed to connect to server:timed out. Any help would be appreciated
Regards john
Ryan Taylor 7th, March 2010 at 9:18 am
@John Have you installed Synergy Server on the computer you have your keyboard and mouse connected to?
John Tempest 8th, March 2010 at 8:36 am
I have installed synergy on both computers. I have set one to be the server and one to be the client. the server icon is in the tray and says it is connected. The icon does not appear in the client tray,but when I open up synergy and start it manually it says it is connected,but still it does not seem to work.Is there something i have missed.Thank you for your patience.
Regards John
John Tempest 8th, March 2010 at 11:31 am
Both my computers are running windows xp pro
Regards John
Ryan Taylor 8th, March 2010 at 11:34 am
@John, I have to admit I've not set it up with Windows as a server before. But I'd trying setting each machine to having a manually set IP address?
John Tempest 8th, March 2010 at 12:21 pm
Thank you for your trouble. I have just realised that the synergy system is for connecting computers with different operating systems. I have surfed the net and found a system called Input Director which I downloaded and had it operating within ten minutes.
Regards John
Mike 29th, March 2010 at 2:49 am
I must say one thing. THANK YOU! Your tutorial was absolutely perfect. I followed it step by step (except for the PC login part) and it works PERFECTLY! I am very thankful that you took the time to put this together and know that it helped one person very well !! Great Job! Took me about 20 minutes to set up since I'm new to iMac and not familiar with settings, etc.. Your tips helped me there also.
Just so you know, I searched Google:
one keyboard and one mouse for two computers iMac
and your article popped up.
Mike
Ryan Taylor 29th, March 2010 at 11:38 am
@Mike - Hearing comments like your really pleases me. :-) I'm glad you've found it useful.