Department of Engineering

IT Services

VNC

VNC offers a way to use machines remotely if you have access to both machines. You can use it to access the Teaching System from your home machine (or do the reverse). See Getting Started with VNC for background details. The Teaching System machines (but not gate) have vncserver but you may need to install software on your machine - see the Downloading VNC page for Linux, Windows and Macintosh versions.

In any situation like this security is an issue. We strongly recommend that you use VNC in combination with ssh. See Is VNC secure? for further information.

VNC at CUED

Since Summer 2010 we've removed vncserver from gate, so if you want to access Central System machines from outside CUED you'll need to follow the instructions on our Remote access to CUED using VNC page to use gate as a relay.

Problems

There could be several reasons why VNC might fail. Before trying it remotely it's worth testing in the DPO - follow the instructions in the Troubleshooting VNC section.

Other problems are
  • Slowness - The linux desktop makes things slow. Try using the twm window manager instead. Note that when vncserver starts, it runs the commands in your ~/.vnc/xstartup file . You can customise this.
  • empty rectangles appear instead of characters - An X server is a program whose job it is to display graphics produced by X clients like xclock, emacs, etc. The X server deals with font-handling etc on behalf of the clients. There are 2 ways that the server can get fonts: the fonts can be on disc (on the machine where the server's running) or the X server can ask another program (a 'font server', which may be on another machine) to give it the fonts. If you start an xterm and type "xset q" you'll be able to find out the "Font Path" of the X server that the xterm is using. This "Font Path" is often a list of directories where fonts will be sought, plus the "name" of a font server (which will look something like "tcp/129.169.14.1:7100").
    The problem is that some programs (e.g. new versions of emacs) want fonts that the default X server run by vncclient can't provide. Before running vncclient run "xset q" to see what the font path was. Then after starting vncclient use "xset fp=...." to set the font path of the new X server. Note that the department runs a font server which is available to Cambridge colleges (details are on our Xwin32 page) so if you're always working from college you could change the font path in the VNC set-up.
  • You run out of disc space - VNC can produce big log-files in your .vnc folder. When you've finished using VNC it's worth removing your .vnc/*.log files.