Last modified: Mar 19, 2012 by Calvat

SSH: how to connect to the center using VNC and SSH

1. Introduction

For users who needs high resolution display at high speed, the Computer Center is testing a remote connection through VNC (Virtual Network Computing). These application (freeware) allows to obtain more interesting performances as a simple X11 display forwarding. In order to guarantee a high security level, VNC should use SSH protocol ("Secure SHell"). These technique is called "ssh tunelling". You will find in this document the way to parameter an ssh tunelling on different operating systems (Unix and Windows). It works also under MacOS X (see Unix).

Be carefull : with VNC, you can not run applications using OpenGL ont the Computer Center interactive cluster.

Alias for using VNC through a ssh tunneling:

Alias	Operating system
ccvli.in2p3.fr	Scientific Linux 5 64 bits

2. To connect to the center using VNC and SSH tunelling from an UNIX workstation

• You should install a VNC client, i.e. vncviewer, from Real VNC.
• If the client you installed supports ssh tunneling (-via command line option) skip the next item/step
• You should run SSH on your local workstation with a free port on the remote workstation (9500 for example).

  > ssh -L 9500:localhost:<Destination Port> <IN2P3 Login>@ccvli.in2p3.fr

  where the destination port can be chosen following the resolution as describe in the next table:

  Resolution	Destination port
  800x600, 24 bits color table	6700
  1024x768, 24 bits color table	6924
  1280x800, 24 bits color table	7180
  1280x1024, 24 bits color table	7200
  1920x1040, 24 bits color table	7820
  2560x1560, 24 bits color table	8460

• Run the VNC client on your local workstation:

  > vncviewer localhost::9500 

• Or if your client supports ssh tunneling (-via command line) use the following instead:

  >vncviewer -via ccvli.in2p3.fr :<Resolution>
  

  where <Resolution> is one of the following: 800,1024,1280,1300,1920 or 2560

3. To connect to the center using VNC and SSH tunelling from a MAC workstation

Download "Chicken of the VNC"

4. To connect to the center using VNC and SSH tunelling from a WINDOWS workstation

• Install the ssh client ("Secure SHell") from http://www.ssh.com.
• Run the SSH client.
• Select the "Profiles" menu.
• Add the profile "ccvnc":
  
  

• Edit the profile "ccvnc":
  
  

• Configure the profile "ccvnc":
  
  

• Activate the ssh tunelling with the "Tunelling" tab:
  
  

• Click on the "Add" button

• Complete the form like:
  
  

• Choose your display resolution and the corresponding port from the next table:

Resolution	Destination port
800x600, 24 bits color table	6700
1024x768, 24 bits color table	6924
1280x1024, 24 bits color table	7180
1920x1040, 24 bits color table	7820
2560x1560, 24 bits color table	8460

• Configure the "Destination port" and validate the modifications.

• Launch the ssh connection:
  
  

• Give your password at Computer Center.

• Run the VNC:
  
  

• Give again your password.

Your are connect to the Computer Center and you are using wmaker under linux SL3.

5. Automatic launch of an xterm inside wmaker

If you want to have an xterm windows lanched automatically at the wmaker start, you should create a . xinitrc file in your $HOME at Computer Center.

You should edit the file .xinitrc and add next instruction before launching wmaker:

xterm &

Example of file .xinitrc :

xterm -geometry 79x25+0+172 &
exec wmaker >.xsession-errors 2>&1