Overview

VNC consists of two components. A server, which runs on the computer you want to remotely access, and a viewer, which runs on the computer you are sitting in front of. There are two important features of VNC:

• The server and the viewer may be on different machines and on types of computer. The protocol which connects the server and viewer is simple, open, and platform independent.
• No state is stored at the viewer. Breaking the viewer's connection to the server and then reconnecting will not result in any loss of data. Because the connection can be remade from somewhere else, you have easy mobility.

So to get started with VNC you need to run a server, and then connect to it with a viewer. First of all, you have to download and install the software on the platforms you want to use. The screenshots on this page refer to VNC Free Edition 4.1, but the general concepts apply to all versions of Free Edition and Enterprise Edition.

Networking

VNC software requires a TCP/IP connection between the server and the viewer. This is the standard networking protocol on LANs, WANs, broadband and dialup ISP. Each computer has a unique IP address and may also have a name in the DNS. You will need to know the IP address or name of the server when you connect a viewer to it.
Sometimes the IP address is fixed, and sometimes it is issued to you dynamically by your ISP. If it is allocated dynamically, you might consider using a third party DNS management service. Try typing "dynamic dns management service" into a google.

Running a Windows server

Installing the Windows server, WinVNC, should create a RealVNC group in your Start... menu. Run the VNC server.

If this is the first time you've used a VNC server on this machine you'll be prompted to set a password, which you'll need when you connect to the machine from a remote location. A small icon will appear in the system tray, and by right-clicking on this you can control most aspects of the server.



The IP address of the computer running the VNC server can be found by hovering over the tray icon in the system tray. Unless this computer has a DNS name, you will need to specify this number to the viewer when you connect.



You can now go to another machine and connect a viewer to the server.

Running a Unix server

To X applications, a VNC server appears just like the standard X display you sit in front of, but without a physical screen attached. The applications don't know this, they just carry on running whether or not a viewer is connected. You can start a new VNC server on a Unix machine by typing:

If you haven't run a VNC server before you will be prompted for a password, which you will need to use when connecting to this server. All your servers on the same Unix machine will use the same password, and you can change it at a later date using

With a normal X system, the main X display of a workstation called ’snoopy’ is usually snoopy:0. You can also run as many VNC servers on a Unix machine as you like, and they will appear as snoopy:1, snoopy:2 etc, as if they were just additional displays. Normally vncserver will choose the first available display number and tell you what it is, but you can specify a display number if you always wish to use the same one:

You can cause applications to use a VNC server rather than the normal X display them by setting the DISPLAY environment variable to the VNC server you want, or by starting the application with the -display option.

For example:
You can kill a Unix VNC server using, for example:

Full instructions for installing and running VNC server for Unix can be found in the RealVNC Site documentation.
Nothing will appear immediately as a result of starting a Unix VNC server. To see anything you need to connect a viewer to the server, see below.

Running a viewer

You can run the Windows viewer the RealVNC group on the Start... menu.


In this case, you will be prompted for the host name (VNC server name) and display number:




Enter it and click OK, and you will be prompted for your password, after which you should see the remote display. If you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

You can run the viewer on Unix and Windows by typing at the command line:

You need to specify the name of the VNC server and the number of the desktop. If, for example, you have started a server as display 2 on a machine called 'snoopy'. Remember that if you are connecting to a Windows or Mac server, the display number will be 0 unless you have explicitly changed it, and can be omitted.

If the machine running the server does not have a DNS entry, you probably won't be able to use the name and will have to replace snoopy with its IP address, for example something that looks like 123.456.78.9.

Using a web browser as a viewer

The VNC servers also contain a small web server. If you connect to this with a web browser, you can download the Java version of the viewer, and use this to view the server. You can then see your desktop from any Java-capable browser, unless you are using a proxy to connect to the web. The server listens for HTTP connections on port 5800+display number. So to view display 2 on machine 'snoopy', you would point your web browser at:


The applet will prompt you for your password, and should then display the desktop.