Synergy KM Switch


Synergy is a cross-platform keyboard-mouse switch. It’s also one of the most well-named pieces of software out there. Here’s why: I had a laptop running XP with a nice usb keyboard and mouse plugged into it. To the right of that, I had a laptop running Linux. Both computers are on a wireless network. Using synergy I can slide the mouse off of the right edge of the screen and onto the Linux laptop’s XWindows screen with no lag. In the process it transfers  keyboard control over to the other system too. You can even cut and paste between systems. This is a great solution for using your desktop keyboard with your wireless laptop or if your laptop is sitting in the living room you could easily use its mouse and keyboard to control your home theater pc. Set up is simple, scales easily, and works with OSX, too.

30 thoughts on “Synergy KM Switch

  1. I’ve been doing this with VNC for years.

    You use x2vnc or x2x if your keyboard’s on a *nix box (in my case, OpenBSD 3.6) It works just as well with other BSD’s, Linux, AIX, and Solaris. I’ve tried it on all of them. x2x works only between *NIX/XFree86 boxes without using VNC.

    You use Win2VNC if your keyboard’s on a Windows box.

    Then, you run a VNC server on your other machines. You can run multiple *2vnc clients on the main terminal, and tell them “North, South, East or West” for the orientation of the other machines you want to control.

    From there, you run x11vnc, macVNC, winVNC, or whatever other flavor of VNC server suits the other machines. As you scoot the mouse off the edge of the screen of your main box, it shifts keyboard focus and starts moving the mouse around on the other screens.

    This hack is nifty and I’ll give it a try, but I use x2vnc daily at work, as I have 3 desktops and sometimes a laptop that I have to work on all at the same time. The concept is nothing new.

    x2vnc: (Page has links to all the other VNC Software I mentioned as well)

    1. yeah sending just the mouse and keyboard data is far more efficient than sending the video data from a headless box to yours over vnc. latency way way lower. this solution is fast enough for gaming.

  2. @ 1

    ive been using vnc for years as well, but this is actually better if you have 2 or more computers physically close with their own monitors. but both apps are useful depending on your needs.

  3. Just last night, I was scratching my head about this precise thing. Thanks for providing a kickass solution, though I doubt it’s much of a hack. Works like a champ. Now to make it a background task.

  4. I’ve been using Synergy for the past few month. Here’s how the setup works. TCP over Firewire between both machines (Both Macs, one runs 10.4.1 and the other 10.3.9). I have a dual input screen – NEC MultiSync FP955 – so I really didn’t need to share the monitor, plus with every app I’ve tried, even on LAN, it’s awefully slow. There is a bit of lag when I’m transfering a file at the same time, but nothing horrible. Getting it to work with Fast User Switch was a bit of a hassle but it’s doable. Only thing that’s quiet pissing me off is that if the server machine – the one with the physical keyboard – reboots (which happens often as it’s a workstation) I need to use some screen sharing app (say VNC) to make the screensaver go out, otherwise Synergy will not work when I restart it via SSH. Took me a while to figure that one out. As for ax0n, yes that’s exactly how synergy works. You make a configuration file (very simple) with your hostnames and the way they are place to each others (left, right, up, down) just like you said for 2vnc. But I admit considering OS X ships with a built in VNC server, it might be an interesting option.

  5. Heh – myself and a homework partner have set up 3 computers with 5 screens between em all accross one of his dorm walls – we were just wondering what it would take to do this sort of thing via the local Lan about a week ago. Wait a week and Hackaday has the open source answer to our needs. I can’t wait to get this running and see the mouse move accross 5 screens in a row :)

  6. I use synergy at home between my linux machine and windows machine.
    Works GREAT esp. during games where you usually can’t use the k/b and mouse on a second monitor.

    Also it’s much better than vnc because it’s got a good deal less bandwidth usasge over the network, and cpu usage on the host machine.

    I use it over a 100mbit full duplex switched network, needless to say it’s blazingly fast and only shows lag when the host computer is lagged.

  7. Well, keep in mind that using the x2vnc, x2x, or Win2vnc programs, you don’t get any of the lag that you’d usually associate with VNC. It simply moves the mouse on the second screen.

    I’m not talking about VNCing over to another machine. I’m talking about running a little daemon on the main machine that uses the VNC protocol to control the mouse and keyboard inputs of neighboring machines, enabling you to do like synergy does, and drag your mouse over to another computer as if it’s all one desktop. Since only mouse and keyboard movements are being sent from the clients on the main computer, and no video is being read to display, it’s very quick.

  8. I just recently found out about synergy on my own, and I agree that this program is priceless. It does the job perfectly! I actually have a hardware KVM, but it wouldn’t work as simple as synergry would for my setup. All it needs now is audio sharing.

    Oh, and maybe a program that can give me more deskspace since I have too many LCD screens! :)

  9. I also use synergy on a pc laptop as the server, and a PowerBook as the client. I have a second monitor hooked up to each laptop, so I end up with 4 screens of computing goodness. ILIKEITALOT.

  10. Synergy is an incredibly elegant solution to a seemingly complex problem. It works well and I felt it was underexposed. From the other comments I think most people agree. I’d post something else, but the tips haven’t really been coming in. So, unless you want underwear hacks from here out send in some links. P.S. tomorrow’s post came from a great tip; I guess it isn’t all bad.

  11. Audio Sharing with Synergy:

    It’s funny cause I thought of the same thing, I have two macs, both running Panther,(synergy only works in Panther and above). The Macs are close enough where I could join the 1/8″ audio jack outputs with a ‘Y’ cable that cost about $5.99 at Radioshak.

    Then I plug my subwoofer/speakers into the tail of the ‘Y’ cable.

    Easy Sleazy.

  12. this is actually the coolest program i have seen in a while. a high five goes to the programmers, and the guy who brought it to my attention, i’m now running seamlessly from my pc to ibook, and i’ve never been happier… just one little problem… no GUI on the os x version?

  13. i hate to admit it, but the first time i’d seen synergy was nearly 2 years ago, when sarah on the screen savers was cutting and pasting text between a windows box and a Linux Machine. the show wasn’t even over by the time i was doing the same between my winbox and one of my Linux computers. the best thing–my father-in-law has worked on computers for nearly 28 years, and this was the first time i was able to beat him to the punch on something very cool and very functional. ***for those using debian—it is available through apt-get***

  14. Back when I was doing the school year book, we had imacs running jaguar. I used this. Then I couldn’t find it after I switched schools. Thanks HACK A DAY!

  15. I have been using synergy for a long time. A few issues still exist and updates are no longer frequent. Besides these few issues, it is a great application that everyone could use. The copy and pasting of text is the best part. Cant wait until the file transfer function works. For windows boxes, just set up a share, and make a send to link. Then right click the file and select send to Laptop. Works for me. I have never experienced these lag issues that people talk about, even when using it on wireless.

  16. So this is rather neat, but it has definate limits.

    Does anyone know of a program that is similar but also transfers desktops? I admin a bunch of machines and being able to mouse to a window edge to control KV&M on another machine would rule.

  17. There’s a similar program for Mac OS X called Teleport – . I have my PowerBook sitting next to my G5, slide the mouse off the screen of the G5 and it pops onto the PowerBook’s screen. It works over Rendezvous, er… *cough* *cough* BonJour.

  18. THis has been out for ages!, It used to be a little buggey but has come a long way since then, i use it from time to time between desktop and laptop, worth the trouble, it isnt completley secure however

  19. I’ve been running this at work for a couple of weeks now (nyahhahhaa you’re late ;-) and it’s really good. I have a desktop and laptop, the desktop is the server (naturally).

    This has made it a lot easier to make full use of both machines, now I can have my email client running on the laptop all the time + I can do the stuff I need to take with me there and on the desktop I have all my citrix, ssh, etc connections open that would otherwise be broken when I pick up my laptop to go to a meeting (or home ;-).

    Only the server’s mouse is able to move to other screens so I don’t even have to disable anything on the laptop end.. I just pick it up, use it as normal, then come back + plop it in the port replicator and after a few secs it reconnects and my server’s input devices are again able to visit the laptop’s screen. Luxury.

    Great stuff.

  20. synergy rocks my world, been using it since january at home and at work. (home: mac os x and debian) (work: mac os x, winblowsxp, and winblowsxp laptop). i have to do multiplatform stuff all day and this really rocks so hard. cut and paste sometimes freakydeaks out and doesn’t work, but only when winblows is involved. the cut and paste saves so much time with text based code, urls, email addies, whatev and i can use my “good” keyboard and mouse on all machines. seamless wonderful cross monitor goodness.


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