HPC/Network Access/Virtual Desktop

Introduction

VNC is a multi-platform graphical remote access mechanism. It is not as common as the X Window System but is more light-weight on the user side and over the network. If you find that remote use over X11 is too slow, try VNC.

Principle of operation

• Start a VNC server on a Carbon node. This is an application that will run in the background and provide a virtual desktop.
• Modify your SSH connection to forward an appropriate port.
• Run a VNC client on your desktop machine and tell it to connect to the forwarded port. This will show the virtual desktop as a window on your actual desktop.
• You can stop the VNC client and reconnect later.
• When done, kill the VNC server process on Carbon.

VNC server startup

• [Log in to Carbon] as documented.
• On the clogin prompt (showing login5 or login6), enter:

vncserver

• You may be asked for a password which will control access to a virtual desktop session. Choose and remember a password of good strength, but not your login password. The VNC password mechanism is weak; think of it as an office door to shut, keeping out unwanted guests.
• To reset your password at any time, run:

vncpasswd

• Note the output of the vncserver command:

New 'login5:1 (stern)' desktop is login5:1

Starting applications specified in /home/stern/.vnc/xstartup
Log file is /home/stern/.vnc/login5:1.log

The number after the : is the display number of your virtual desktop.

Forward SSH ports

Forward a (TCP) port from your machine to the same port on the Carbon login node. How to do that depends on the SSH program you use.

For Linux and Mac

• Press <Enter>~C (three keys in succession: Enter, tilde, capital C). You should get a prompt like this:

ssh> 

• At the prompt, enter:

-L port:localhost:port

where port = 5900 + displaynumber from above, for example:

ssh> -L 5901:localhost:5901
Forwarding port.

• Press <Enter> to regain your regular prompt.

For PuTTY on Windows

TBD

VNC server teardown

vncserver -kill :displaynumber