VNC is a nifty program for controlling another computer across a TCP/IP network.

Download VNC (version 3.3.3r7)

The VNC zip file contains both parts of the VNC package – the VNC viewer and the VNC server.

1. Double-click on the VNC zip file. Extract the files to a temporary directory.
2. Go to that temp directory, open the ‘vnc_x86_win32’ folder, and then open the ‘winvnc’ folder.
3. Look for the ‘setup.exe’ file in that folder (it may show up as the Setup Application depending on how your folder viewing options are set), and double-click on it to start it.
4. The installer will run, and it's one of the standard installers so it'll be pretty straight-forward.

In normal operation, there will be two computers involved – the one you're working from, and the one you want to control from a distance.

1. The one you want to control will have the WinVNC application running. It acts as a server, i.e. it opens a listening port, and waits for something to connect to it. To start the application, go to Start => Programs => VNC => Run WinVNC (app mode). When it starts up, it'll place a VNC icon in your system tray. We'll get to the settings in a moment.
2. The computer you'll be working from will run the VNC Viewer. To run that, go to Start => Programs => VNC => Run VNC Viewer. Don't choose VNC Viewer (listening mode) – that operates a little differently. The VNC Viewer acts as a client application – it will send a connection request to the distant computer, and try to connect to WinVNC.

Application To configure the WinVNC application, find that little icon in your tray and right-click on it. Choose ‘properties’. It usually takes a little while to come up, so wait around for a bit. Here's a screenshot of the properties dialog box, along with the settings that seem to work pretty well.

Display Number - This is the port, sort of. A display number of 0 equates to port 5900, the default port; a display number of 1 equates to port 5901. Display numbers above ‘99’ will be interpreted directly as port numbers, without the offset.

Password - This is your primary protection for this connection. The user connecting in will be required to give this password before he/she can do anything else. The program accepts up to eight characters, and its case-sensitive. Here, we've left the program at the default port setting.

Now, let's set up the viewer to connect to it. When you go Start => Programs => Run VNC Viewer, you'll see a screen like this:

The box will be blank when you first see it, of course. As you use it, it will save the various Server addresses that you use in the drop-down box. The viewer box uses the same port conventions as the Server properties – you put in the Server address in the form ‘IP address:port’, and the port numbers from 0 through 99 are interpreted as offsets from 5900. Bigger numbers are interpreted directly as port numbers.

If you wanted to connect straight through to the Server you had just configured, a port number of ‘0’ or ‘5900’ would do the trick – they mean the same thing, and connect to the default port. The setting shown here isn't a mistake, but it doesn't make sense until we get through the next section. Remember, too, that if they have a firewall at the other end that the firewall’s external IP address is the only address you can connect to. If a connection needs to go to a machine behind the firewall, somebody has to configure that firewall to do it.

If you click on the ‘Options’ button you'll see this screen.

Most of these settings you can leave at the defaults, but if you've got a modem connection at one end or the other you'll find that the whole thing is really slow if you don't click the ‘Restrict pixels to 8-bits’ box.

There are two basic configurations that you have to worry about with a firewall involved. The first is when the firewall is on the client side – meaning the firewall is between the VNC Viewer and the Internet – and the second is when the firewall is on the server side – that is, between the VNC app and the Internet.

• The first case is easy with WinProxy 3.0 – you don't have to do anything at all if you're running Transparent Proxy, as most people will (it's the default). If you were using WinProxy 2.1, you'd have to set up an Outgoing mapped port. WinProxy 3.0 will do all it needs for the connection, on the fly, without an outgoing mapped port.
• The second case will require that you set up an Incoming mapped port to get the connection through the firewall.

[Okay, an aside here. The firewall in 3.0 is more comprehensive than in 2.1, and more complex to configure on your own. There's one thing you've got to do, whether that connection is coming to the WinProxy machine, or to a client machine behind it – you have to use the Filters to allow an incoming connection on the port that will be used; and there's something else you probably have to do – map an incoming port. The latter can only be skipped if the connection is to the WinProxy computer itself, and can never be skipped if the connection is to a client computer behind the firewall. It's tough to explain the differences between opening ports (like a mapped port) and allowing ports (with the Filters), but there's an easy way out. Whenever you define a mapped port, WinProxy will automatically put in any and all filters that you need, and you don't have to mess with filters at all. That's the way we're doing it here.]

Okay, here's our mapped port in WinProxy. Even though we're setting up the connection to the WinProxy machine itself, we used a mapped port to open up the firewall, and allow the connection to the Internal WinProxy port. To make the mapped port to any other client network connection, you only have to change the Destination IP address.

You'll notice the 5920 port we mentioned earlier. We could have left both the Proxy Port (the ‘listening’ port) and the destination port at 5900, but since that's the default setting for every copy of VNC in the whole world we changed it. The viewer sends on a non-standard port, and WinProxy awaits the connection on that same non-standard port. WinVNC waits on the default port, but its behind the firewall). It's a simple dodge, and maybe a little paranoid, but if you mess with firewalls long enough you start doing things like that just on principal.

It's been a long series of instructions, but once you're set up you'll find this an easy program to use. Sit down, bring up the viewer, and click on the drop-down box. Pretty quickly it'll ask you the password, and you know you're connected – it's the machine at the far end that's asking for a password. The far machine's screen should start loading on your machine within seconds.

VNC is a program freely available from http://www.uk.research.att.com/vnc/ following the standard (GNU Public License) conventions for using and promulgating open-sourced programs. It's a great program, and we really appreciate these folks making it available to the general public.