Overview
Synergy is a tool allowing to bound all the workstations one uses to one common set of input peripherals (i.e. mouse and keyboard). It services also transferring the clipboard content between workstations, so greatly enhances the productivity. It is provided for Windows, Linux and Mac OS X, so I would say it covers 99,99% of the workstations' os population.My architecture
My architecture means 2 laptops - the 1st one run by Linux (current Ubuntu) and the 2nd one run by Windows 7. The package is called synergy in version 1.7.0. and on Windows side I have synergy in version 1.3.4.My configuration
The synergy on Linux side is configured to be a server. The keyboard and mouse of the Linux workstation is the common input set then. On the Windows the software works as a client. As I have a community version, the communication between workstations would not be secure if I would simply rely on the Synergy itself. One may buy the PRO version to have the transfer secured by SSH and I suppose this is a very convenient solution. Here I provide a "poor-man" solution where synergy communication is transferred through SSH tunnel.Client and server insecure configuration
For the client I check the 1st radio button (Use another computer's keyboard and mouse) here and specify the IP of the server.For the server I choose here the Server checkbox and configure interactively - on the interactive configuration window I set the order of the workstations. I believe that the available screens are displayed by checking all the available clients, so I would start with the insecure connection. The connection would be done on the 24800 port.
As You may see this configuration is very easy.
Securing the connection
Now time to secure it. I did it by opening a SSH tunnel from the client to the server, so actually all is done on Windows side (which has some pros and cons). The only thing on the server is a SSH key generation (ssh-keygen -t rsa -b 2048).First thing on Windows is a download of the Putty SSH client. Then I generated an SSH key (PUTTYGEN.EXE SSH2 RSA algorithm and 2048 bits for length) and save both keys (private and public) to files. Next I put the public key to the server's authorized_keys file to connect by key ($HOME/.ssh/authorized_keys - if it does not exist, just create it with Your favourite editor). To move the key one may use currently working insecure synergy installation :-).
Additional step is to build a batch file to run pageant.exe (which is SSH agent to keep the password in memory to open the key)
REM content of the batch file
start "" c:\app\putty\pageant.exe "C:\Users\{user}\Documents\win2priv.ppk"
This batch file has to be put to Startup group to run just after the Windows initialization.Further I needed to create an executable to establish a tunnel to the server. I tried to do it with another batch calling plink.exe (another executable from Putty), but it did not work (may be I did something wrong), so I tried configuring a session in Putty - to do it one have to call Putty, create a session to the server and then in Connection->SSH->Tunnels add an entry (Source port: 24800, destination: 127.0.0.1:24800 and options Local and Auto) with the Add button.
Now we are ready to open the connection to the server (beforehand however we need to disable current synergy connection as it is established on the same port). After clicking the Open button one have to set the server IP to 127.0.0.1 and run the synergy client with the Start button.
Important notes
Due to some reason not clear to me usage of Putty failed and I had to exchange the Putty binaries with Kitty binaries (which is pretty much the same). With Kitty whole thing started to work smoothly.Pros
The connection is secure :-)Cons for Linux being server
- during the Windows initialization the SSH agent will ask for the password to the SSH key
- one have to open a tunnel manually - You may try with plink.exe (klink.exe from Kitty) - this probably may be replaced with some Powershell script, but I have no ability to manipulate the Powershell scripts here
Cons for Windows being server
- on the Linux side all things may be nicely automated - no problem with opening a tunnel in background
- one have to install and run an SSH server on the Windows side
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