Setting up a tunnel with putty, jump server for using synergy

Question

Long time ago I set up an environment where my Linux machine (LM) was a synergy server and my Windows machine (WM) the synergy client as described here.

Since our admin put in a Linux jump server (JS) I'm not able to tunnel between both machine.

Here some question: On the windows machine I configure Putty in that way:
Session -> HostName: jumpserver Port: 22.
Connection -> SSH -> Tunnels L24800 LM:24800.

My understanding is that a connection to the jump server will be set up and the a ssh hopping starts to the Linux machine. Even if I have a logging on the jump server I can not confirm that the tunnel is set up. Even I miss the part where I'm telling the JS to forward all requests to the LM and vice versa.

If I used with Putty Connection -> SSH Remote command and putted ssh LM the first time I recognized that I was able to set up a connection to the JS and then to the LM. But synergy did not accept that way.

How can I set up a tunnel from a Windows machine with Putty over a Linux jump server to a Linux machine? How must I configure synergy?

Thanks in advance.

Solution

You need two port forwarding, the first from JS to LM and the second from WM to the previously created on JS. Add to your Putty configuration the following line in the SSH menu under remote command:

ssh -L 24800:localhost:24800 LM

Under Tunnels configure the port forwarding like you are connecting directly to the LM

L24800 localhost:24800

Once you connect with Putty from the client machine WM to the jump server JS, you can check the Event Log to see if the tunnel is up. Just click with the right button on the bar at the top of the Putty window anche select Event Log in the menu. You should see something like this:

2014-05-21 18:14:16 Local port 24800 forwarding to localhost:24800

Your client should be configured to connect to localhost:24800.

Comments

[Clueless]

Thanks, in the event log I saw an error message: 'forwarded connection refused by server administratively prohibited open failed' I changed the port 24800 to 22. The tunnel is set up now.

[Guido Vaccarella]

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