Technology Support — MCFL

VNC for Remote Desktop Viewing

March, 2005

One of the most difficult aspects of helping someone with computer problems over the telephone is not being able to see what is on their screen. And the most time-consuming aspect of providing on-site tech support to different locations is the driving time needed to get to each site. So software that allows tech support staff to view computer desktops remotely is extremely helpful for Tech Support staff and for the people they support.

For over two years, we've been using software called VNC, or "Virtual Network Computing", to remotely view desktops of computers around the system. VNC was chosen because of certain advantages over other types of remote desktop software:

The main disadvantage of VNC over similar products is that it has to be installed onto a computer ahead of time, so we can't view somebody's computer desktop "on the fly" without planning ahead. Yet we are now close to the point where VNC is installed on all of our staff PCs.


How VNC Works on Your PC

A VNC installation on any computer consists of two parts:
  —A VNC Server (a Windows "service"), which can serve up a picture of the desktop
    of the comptuer it's installed on, and
  —The VNC Viewer, which is a small program that can be used to view a computer running the VNC Server from over the network.

  The Server part of the program is the part that puts the VNC icon (the black "V" on a white background) in the system tray when it's running. If the Server isn't running, the computer can't be viewed using VNC.

To access any computer using the viewer, one needs to know the IP address of the target computer, and the password that is set up when VNC is installed. Only Tech Support staff know this password, so that only they can access computers remotely.

  If Tech Support staff call you and need to ask you the IP address of your computer, there's an easy way to get this information from the VNC icon. Just hover over the icon, and it will display the IP address that your computer is using on the network.

This computer is being viewed from somewhere else.
  If your computer is being viewed using VNC, besides any obvious signs (such as the mouse moving by itself, or programs opening and closing by themselves) the VNC icon will change color. Most notably, the V icon will turn white.

For people interesting in the technical details, the VNC server broadcasts its image of your PC over port 5900. For this reason, our VNC servers can't be accessed from outside of the Library's networks, as all incoming ports except 80 (web) and 21 (ftp) are blocked at the firewall. The password for accessing a computer using VNC is encrypted, but the content of any viewing or typing over a VNC connection is not encrypted.

We use the version of VNC called "TightVNC." It is designed to minimize the bandwidth needed to view machines remotely. The other popular version of VNC is "RealVNC," and the servers and viewers of the two programs are interoperable.


Using VNC Over The Network

  1. Tech Support staff will always ask permission to VNC to, or view your machine remotely.

  2. There are times when it works best for Tech Support staff to have you do things on your PC while we observe, and at other times, we will need to do work ourselves on your PC, and you may observe. We'll try to be clear about who should be "driving" the PC at any point in time.

  3. VNC is installed and running on most Public Internet computers. On these computers we have "suppressed" the VNC icon so that it can't be clicked on by public users. (There is no way to keep users out of the program settings if the icon is there.) We will only use VNC on public machines to update or troubleshooot them, and only when they aren't being used. We will verify that they aren't being used by calling the Reference Desk of the Library in question.

  4. VNC has the capability of being used for surveillance of computers remotely. It is not our intention to ever utilize this aspect of the program, and in fact, it makes a very poor surveillance tool. Even without the VNC icon changing color, you can almost always tell when someone is viewing your machine using VNC, as the mouse will perform very strangely.

  5. Aside from supporting staff machines, our other use of VNC software is to administer servers. We can run a server without a monitor, or in a place that we rarely visit such as Room 104 of the Civic Center building, and reach the machine over its network connection when needed.
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Last modified Mar. 8, 2004