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  1. Computer Skills

Use One Keyboard and Mouse Across Different Computers and Operating Systems

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9 min read

Nowadays it is not an common scenario to work with both a Mac and Windows operating systems. Linux, too. To use two separate machines there's two options:

  1. have two keyboards and mouse at your desk, or
  2. use a keyboard/video/mouse (KVM) switch to switch between the two computers

A software based keyboard-mouse switching app, when considered, will save desk space from unnecessary cable clutter.

Synergy allows control of multiple computers, each with their own monitor, from one keyboard and mouse. Move the mouse to the edge of one screen and it jumps to the screen on another computer running a different operating system.

In this tutorial, I’ll show you how to

  • Configure Synergy to use one keyboard and mouse seamlessly
  • Make use of this application to increase productivity

Pre-Requisites for Running Synergy

Synergy is fully supported on the following operating systems:

  • Windows XP SP3 through to Windows 10
  • Ubuntu 14.04
  • OS X 10.7 Lion through to macOS 10.12 Sierra
  • RedHat 6 and above
  • Fedora 19–21

Synergy will not work on systems running:

  • Windows NT, 95, 98, 2000, ME, XP SP2
  • Operating systems up to and including OS X 10.6 Snow Leopard
  • Linux systems running OpenSSL 1.0.1 and below (for encryption support)

Systems running Synergy must be on the same local network (can be wired or wireless). You should at least connect one keyboard and mouse to a system, preferably the server computer. 

Synergy is a KBM application (KeyBoard and Mouse), not KVM (Keyboard, Video, and Mouse) so each system must have a monitor in working condition.

Installing Synergy

Download the latest version of Synergy from the symless website and install it on all the systems. Ensure that you to download the correct version of Synergy.

  • macOS: Synergy app is available for different version of macOS. You need to know the version of macOS you’re using. Click the Apple menu and choose About This Mac. Note down the version displayed in the Overview section. For example, If you’re using El Capitan then download the Synergy app labelled with 10.11. Similarly for Yosemite, download the Synergy app labelled with 10.10

  • Windows: You need to know whether you’re using 32-bit or 64-bit version of Windows. Press Ctrl + X and click System from the menu. If you’re running a 64-bit version of Windows, 64-bit Operating System is displayed in the System type field under the System heading. If you’re running a 32-bit version of Windows, 32-bit Operating System is displayed in the System type field under the System heading.

  • Linux: Synergy app is available for different Linux distributions. Download the app according to the type of distribution and note whether it’s 64-bit or 32-bit.

symless-synergy-download-pagesymless-synergy-download-pagesymless-synergy-download-page
Synergy download page. Before downloading Synergy note the OS version and whether it is 64 or 32 bit

How it Works

Synergy app works on a client-server model. The server is the machine that has the keyboard and mouse. These run the Synergy server processes synergys

The clients are the machines whose desktops you wish to connect with the server. These run the client server processes synergyc

You tell Synergy the way your screens are laid out and it sets up the connections accordingly.

Synergy uses the Bonjour protocol to aid in service discovery, address assignment, and hostname resolution. It locates other computers, or clients, to automatically find the Synergy server and services that those devices offer over a local network.

Run Synergy Automatically at Startup

When Synergy starts during a computer’s boot up process, it automatically logs in to the client machine using the server’s keyboard and mouse. This allows you use the keyboard and mouse among multiple computers instantaneously.

On Windows

The latest version of Synergy app uses the Windows Service feature which works with Windows Vista and onwards. 

These services can be automatically started when the computer boots, can be paused and restarted, and do not show any user interface. To have Synergy not start on boot and control them manually, secondary-click the Synergy service and click Properties.

windows-services-propertieswindows-services-propertieswindows-services-properties
Choose properties from the context menu to control the Synergy foreground processes

From the Properties window, change the Startup type from Automatic to Manual.

change-startup-type-synergychange-startup-type-synergychange-startup-type-synergy
Change the Startup setting from Automatic to Manual if you wish to in Windows

On Mac

In all the versions of OS X and macOS, you can have the user login automatically and set Synergy as a Login Item. 

Open System Preferences and click Users & Groups. Find the Profile you’d like to set apps to launch, then toggle Login Items. It will show you the list of all the items that are scheduled to launch when you log in.

login-items-preference-maclogin-items-preference-maclogin-items-preference-mac
Synergy app listed in the login items of Users and Groups Pref Pane

To add Synergy app to this list, click the + sign to launch Finder, select the app and choose Add

To hide the Synergy app on startup, check the Hide on startup in Synergy preferences.

Configuring Synergy Server and Client

Synergy app works on a client-server model. It needs to know about all the clients that will connect to it. To tell the server about these clients, click Configure Server. A new window will open with grid lines drawn on it. 

Synergy app imposes a five-by-three limit of screens as seen in the screenshot, below, although it is possible to have more screens by editing the Synergy configuration file manually.

synergy-configure-server-and-clientsynergy-configure-server-and-clientsynergy-configure-server-and-client
Synergy GUI to configure server and clients. With mouse drag the computer icon from one cell to another. You can only drag the icon and it is not possible to superimpose them. 

To add a new client, drag the monitor icon onto the grid. Once you have added a client to your grid, it will have the name Unnamed

Double-click the icon to change the name of the client. You must use the client name that Synergy shows on the client. This can be found by looking at the main window of the Synergy app, look for the line labelled Screen Name under the Client section. 

If you have decided to rename them, then you have to tell Synergy the name of the screen using a command line option.

change-the-name-of-synergy-server-and-clientchange-the-name-of-synergy-server-and-clientchange-the-name-of-synergy-server-and-client
Change the name of Synergy server through this screen. Follow the same screenshot on the client machine. 

To remove a client, drag the monitor icon to the trash can in the upper left. To move a client, drag the existing monitor icon to another cell. 

Once you have added all the clients, restart Synergy and click OK to return to the main window. You should note the IP Addresses line at the top of the main Synergy window. 

I’ll use one of the IP addresses listed here, in bold letters, on each client computer to connect it to the server.

ip-address-listed-in-the-synergy-windowip-address-listed-in-the-synergy-windowip-address-listed-in-the-synergy-window
IP address listed in the main Synergy window. Check the Auto config in the client machine to let it automatically discover the server machine. 

Once you’ve configured the server, connect each client to the server. 

Assuming that you selected Client option during the installation, this option should be checked on the main window as well. Since the Synergy application uses the Bonjour protocol to locate computers over the network—in this case server, you don’t have to fiddle with anything in the client machine unless the requirement arises. 

No matter how many clients you add, you must click Apply and Start on each client to save the configuration.

synergy-windows-running-as-clientsynergy-windows-running-as-clientsynergy-windows-running-as-client
Synergy running on the Windows machine as a client

Assuming that you have done the configuration correctly, few problems may still crop up. When the client does not connect:

  • Check the error log messages in the main window. Look out for status with Connection timed out or Connection refused messages. Check whether the client has connected to a correct server IP address. If not, uncheck Auto Config to manually configure the IP address
  • Check whether the firewall is blocking an incoming or outgoing connection or not. Open the firewall settings and delete all Synergy related exceptions rules. Grant Synergy network access if the firewall warn message appears
  • Anti-virus software may inadvertently block the Synergy app. In this case, add an exclusion criteria for the Synergy app
  • The port number on the Synergy client must be set to the same number as the port number on the Synergy server. You may check this by going to Edit > Settings on Windows or Synergy > Preferences on Mac to display the port number that Synergy will use. The default is 24800
synergy-main-window-and-preferencessynergy-main-window-and-preferencessynergy-main-window-and-preferences
Synergy main and preferences windows on a Mac. Same setting exists on Windows as well

Making Use of Synergy

Drag and Drop Files

With Synergy you can drag and drop files between computers. This is supported on Windows Vista and newer, and OS X 10.7 and newer and macOS

Drag a single file icon to the edge of the screen in the direction of the client or server, and the file will be copied to the desktop of the other computer few seconds later. 

It has some limitations, you cannot drag and drop folders and the transfer may not work if you’re using SSL—feature associated with Synergy PRO.

To disable this feature, click Configure Server.

configure-server-to-enable-drag-and-dropconfigure-server-to-enable-drag-and-dropconfigure-server-to-enable-drag-and-drop
Click this button to open Advanced server settings

A new window will open. 

Click the Advanced server settings tab and uncheck Enable drag and drop file transfers.

uncheck-drag-and-drop-option-synergyuncheck-drag-and-drop-option-synergyuncheck-drag-and-drop-option-synergy
Uncheck drag and drop file transfers between the server and client or vice-versa

Share Clipboard Between Computers

A synchronised clipboard ensures that the clipboards of multiple computers are always identical, so that data can be moved between different computers using the familiar copy-and-paste model. 

Synergy is based on the similar principle. Select an item on one computer, copy it to the clipboard—using the standard Copy command, then switch the mouse to another computer and paste the item—using the standard Paste command. 

You can copy and paste an item from server to client and vice-versa.

clipboard-capture-updated-from-log-statusclipboard-capture-updated-from-log-statusclipboard-capture-updated-from-log-status
Clipboard is successfully captured as seen from the display log

Lock the Remote PC With Ctrl-Alt-Del

If you have a Windows machine running as a client then with the default setting you cannot enter a Ctrl-Alt-Del command over Synergy on the Windows lock screen. 

This can be frustrating if you lock your computer frequently or log in remotely. You can change this behaviour through Local Group Policy Editor.

Press Win-R and type gpedit.msc in the Run menu. Go to Computer Configuration > Administrative Templates > Windows Components > Windows Logon Options.

group-policy-setting-to-lock-remote-pcgroup-policy-setting-to-lock-remote-pcgroup-policy-setting-to-lock-remote-pc
Open Group policy editor to lock or unlock remote PC. Your client should be Windows in this case. 

Open up the Disable or enable software Secure Attention Sequence. Set it to Enabled and then select Services and Ease of Access applications below, click OK to Apply. 

You are now be able to issue a Ctrl-Alt-Del to Windows over Synergy to lock the screen.

enable-software-secure-attention-sequence-in-windowsenable-software-secure-attention-sequence-in-windowsenable-software-secure-attention-sequence-in-windows
Enable software Secure Attention sequence in Group Policy Editor. 

Move Your Mouse Without Any Friction

If you use Windows as a Client machine then you'll notice that certain applications stop you from moving the mouse off-screen. This may dampen your experience while using Synergy

This is usually due to UAC in Windows. You should not disable UAC for this purpose. Instead, in the Client machine click the Edit menu and choose Settings. A new window will open. Now select Always under Elevate section. 

move-mouse-without-friction-synergymove-mouse-without-friction-synergymove-mouse-without-friction-synergy
Check the Elevate mode to Always to move the mouse seamlessly between machines

Conclusion

Synergy is a powerful, cross-platform application that lets you use one keyboard and mouse among multiple computers. 

The user interface is inherently complex and is quite difficult to setup. But once you set it up, it runs smoothly. 

In this tutorial, I have shown you how to configure Synergy server and clients, sort out issues during the setup process, and take advantage of this application.

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