Recently, I’ve written several articles on Windows XP’s remote desktop feature, but other remote control and terminal emulation products such as Symantec's pcAnywhere and Procomm Plus have been around for years. While these programs are excellent, there’s another remote computing solution, Virtual Network Computing (VNC), which provides an easy way to remotely control computers running a wide variety of popular operating systems. In this article, I’ll explain how VNC works and why it might be a good solution for your organization's remote computing needs.
The birth of VNC
In 1994, the Olivetti and Oracle Research Laboratory (ORL) introduced a very thin client, ATM network computer named the Videotile. The term "ATM network computer" is somewhat misleading, however; the Videotile wasn’t actually a computer but rather a display device with an LCD screen, a stylus, and a fast ATM network connection. The Videotile contained an extremely thin client and acted as a viewer in much the same way that pcAnywhere does.
Learn more about ATM
For more information about ATM and how your organization can benefit from it, check out this article by Warren Heaton.
VNC is a software-only version of the ATM network computer. It allows you to remotely control a host system in a manner similar to pcAnywhere or Windows XP’s remote desktop. However, there are several very compelling reasons to use VNC instead of the other remote control software products.
Price and multiplatform availability
The first compelling reason to use VNC is its price: It's free. You can download both the software and its source code from AT&T Laboratories Cambridge's VNC home page.
Also, there are versions of VNC available for a variety of platforms. There’s a version for Windows that supports Windows 9x, Windows NT, Windows 2000, and Windows XP. Separate versions are also available for Windows CE, DEC Alpha, Macintosh, Solaris, and Linux. Although each version must be downloaded separately, the download shouldn’t be too time-consuming. I downloaded the Windows version, and the entire thing was less than 900 KB—small enough to fit on a floppy disk.
Perhaps one of the biggest reasons for using the VNC software is that it’s cross-platform compatible. For example, you can use a Windows machine to control a Macintosh machine or you can use a DEC Alpha to control a Linux machine. You can mix and match operating systems at will. In fact, I have a friend who uses VNC to monitor his UNIX servers from his office using a standard Windows 2000 Professional workstation.
Simple, yet stable and powerful
The entire concept behind the VNC software is to be small and simple. In fact, the viewer portion of the software doesn’t even have to be installed on a PC. It can be run directly from a floppy disk. It allows you to connect to or disconnect from a host from any computer. One of the biggest advantages to having such a design is that the viewer doesn’t record any information about the state of the host. This means that if your viewer PC were to crash or if you were to reboot, there would be no danger of affecting the host machine or any applications running on it. Upon reconnecting to the host machine, you’ll find the host and its applications exactly the way that you left them. Also, the component that runs on the host machine is designed to be small and unobtrusive.
Another unique feature is that multiple viewers can simultaneously connect to a single host. By doing so, you can allow a group of people scattered all over the world to watch as you perform a procedure on a host machine. The exception is Windows NT Servers, which support only a single connection.
The only real requirement for using the VNC software is that there must be a TCP/IP link between the host and the viewer. The two machines may exist on the same physical network or be connected via a dial-up link or the Internet.
The bottom line
VNC is fast, simple, and has few disadvantages. The only real issue I know of is a potential display problem when using two computers with very different video display settings. For answers to frequently asked VNC questions, check out the VNC FAQ.
In addition, VNC has one more surprise up its sleeve. Because the VNC source code is available, versions of the VNC software have been written by users to support other operating systems including Amiga and SunOS. You can find all of the user-developed versions of the VNC software on the VNC platforms page.