2 years ago while scanning A Whole Lotta Nothing I found the promise land. A hack that I’d been waiting for my entire life. A way to use one keyboard and mouse with 2 different computers with no hardware assistance.

The History

First there was dual monitors attached to a single computer. Look mom, my cursor is going from one monitor to the other! Then there was the KVM switch connecting 2 computers to one keyboard, mouse, and monitor. And it sucked. Then Matt Haughey showed me the ways of VNC hacking. With special software I was able to connect to a remote computer (sitting on my desk to the right of me, yes I know, not so remote) via its VNC server by just dragging my mouse over to the right edge of my screen. The software I had running on my main computer would then translate every move I made with the mouse and keyboard to the VNC server on the remote computer, essentially allowing me to use my mouse and keyboard on the other computer. It was great. I was literally able to drag my mouse from one monitor to the other, even though each monitor was being powered by 2 different computers. It was magic! Well, until I couldn’t get my mouse back to the first computer and it was stuck on the remote one. Fun. End of promise land.

Enter Matt Haughey once again. 2 years later.

I was perusing his site once again and came upon another how to on achieving the same idea: One keyboard and mouse, 2 seperate computers. This time using the project Synergy, which was made for this type of setup.

Synergy allows you to run a server and multiple clients. Its a bit confusing but in this model, the server connects to the clients, or rather the clients connect to the server allowing the server to use its input devices on them. Basically the server runs on the computer that your mouse and keyboard are connected to, and the client software runs on the computers that you want to use your mouse and keyboard on.

So in my landscape, my server is my PowerMac, and the client is my Suse media server. I load up and configure the server on my PowerMac, and do the same for the Suse box and voila! I can drag my mouse over and back. One keyboard and mouse! Its great, and so far so good. No bugs, works great, and copy & paste is fully supported.

Now, onto the important stuff. How did I get it set up!

Setup

Well basically I’m using all commandline versions of Synergy. While the OS X Gui app for Synergy is nice, I wasn’t able to get it to launch the server in Tiger. So I went with the ultra low key, out of sight command line version. I was able to install it on the Suse box through YAST. As for the OS X version, I use the precompiled binaries available on the Synergy project page. No compiling needed!

Configuring

Once these are installed, I had to configure them. Its a little tricky, but the good news is that they use the exact same config file. The configuration file has 2 sections: Screens and Links.

Screens allows you to determine exacly which computers will be used in the setup. You see that in my setup I have mediaserver and powermac. These aren’t just names of computers they are actually the host names of these particular computers. You may need to modify your hosts file to allow synergy to know exactly which computers you are talking about. In a nutshell, your hosts file associates an IP address to a name. This way you can name a computer, rather than dealing with its IP address. I will go into this below.

Links allows you to define the placement of the comptuers. On my desk, my PowerMac is directly in front of me, its my main computer. The Suse box is on my right. So in the config file I state that the right edge of the PowerMac will send the cursor to the mediaserver and the left edge of the mediaserver will send the cursor to the PowerMac.

The Synergy configuration file is located at /etc/synergy.conf.

section: screens
	mediaserver:
	powermac:
end
	
section: links
        mediaserver:
                left = powermac
        powermac.local:
                right = mediaserver
end

It’s that simple!.

Starting Up

Once you’ve configured everything correctly. Its time to start everything up. From the command line on the computer that will be hosting the server enter:

# synergys -f -1 &

Now, from the client computer start the client software telling it to connect to the server computer, in this case my PowerMac:

# synergyc -f powermac &

The ampersands at the end of each command allow the processes to continue to run once you close the terminal. It is important that your computers know the host names for these computers for ease of use. Edit your hosts file as root so that each computer knows each other. The hosts file is /etc/hosts in linux and /private/etc/hosts in OS X. Simply add the IP and host name of each computer and you will be all set up.

192.168.1.10	powermac
192.168.1.12	mediaserver

Finite

So far, I’ve found Synergy to be really robust. For example, if I shut down the server and restart it, the client connects back to it immediately. There is no need to tell it to reconnect. I was pretty impressed with that part.

What Synergy won’t do is copy and paste files or allow you to drag them over. I know it sounds like a silly expectation, but you’d be surprised at how many people are disappointed in not having these features. These are bit out of the scope for this application and I think it would just cause problems trying to develop them.

Outside Resources

Synergy Project Page
A Whole Lotta Nothing - Matt Haughey
Synergy OS X Gui

This entry was posted on Thursday, June 16th, 2005 at 12:55 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.