Virtual Network Computing

Mr. Harvey tells us about the VNC software package and how to set it up to control MS Windows servers from Linux.
Using the Linux VNC viewer

Once you have WinVNC running on a Windows server, try connecting to it from your Linux desktop by typing (within X) the following command, followed by the password you gave when configuring WinVNC (if any):

> vncviewer
vncviewer: VNC server supports protocol version 3.3 (viewer 3.3)
Password:
vncviewer: VNC authentication succeeded
vncviewer: Desktop name "boxster"
vncviewer: Connected to VNC server, using protocol version 3.3
vncviewer: VNC server default format:
16 bits per pixel.
Least significant byte first in each pixel.
True color: max red 31 green 63 blue 31
   shift red 11 green 5 blue 0
Using default colormap and translating to BGR233
Creating window depth 8, visualid 0x22 colormap 0x21

If you typed the password correctly, several lines of information will appear and a new large window will pop up showing the entire remote Windows desktop. When you are finished using the VNC viewer, simply close the viewer's window to close the connection. The remote Windows desktop will be left in the last state the viewer left it in.

Figure 3 shows a sample Linux desktop with a newly opened VNC viewer connection “viewing” a Windows NT desktop.

Figure 3. Linux Desktop Viewing Windows NT

A nice feature available in recent VNC releases is the ability to send the infamous ctrl-alt-del key sequence to the Windows desktop shown in a VNC viewer. This feature has distinct advantages when the VNC server is installed as a service:

  • If the VNC server is installed as a service under Windows NT, you don't need to have a user logged on all the time with the VNC server running as a Windows application. When it comes time to use that server remotely, simply connect to it with a VNC viewer, press ctrl-alt-del to get the NT login Window, and log on as you normally would to the NT box.

  • If you need to stay logged on to the NT server but want to exit your local X session, you can type ctrl-alt-del to get the “Windows NT Security” pop-up window, click on “Lock Workstation” to lock the console, close the VNC viewer connection, then exit your X session. You will still remain logged on to the NT server; its screen is now locked.

Advantages

The VNC protocol has several advantages. The main one is that it is stateless. A user can close a connection to a remote desktop from one VNC viewer and later reconnect to that same remote desktop from the same or different VNC viewer, and it will be in the same state.

When using the Java VNC viewer, a system administrator can control a Windows 95/NT, Macintosh, or UNIX desktop from anywhere in the world using a Java-enabled browser. The VNC server can be configured so that all incoming viewer connections will be able to see the desktop but will not be able to move the mouse or type anything (a read-only connection). This option comes in handy in a teaching environment, where each student in a class connects to the instructor's “desktop” and watches a demonstration on his own computer rather than on an overhead connected to the instructor's computer.

How I Use VNC

At work, I have an Alpha running Digital UNIX and a P133 running Windows NT 4.0. Although I am strictly a UNIX systems administrator, my company's e-mail standard is based on Microsoft Exchange. Therefore, I am required to have a Windows desktop on my desk in order to read Exchange e-mail. However, at home I run only Linux. I was looking for a way to read my Exchange e-mail from home. After reading about VNC, I knew I had found what I was looking for.

I use the Linux VNC viewer at home to connect to the Windows NT box on my desk at work over a PPP connection. Figure 4 shows me reading my Exchange e-mail with such a setup. While VNC performance over a PPP line isn't spectacular, it is very usable and solves my problem of not being able to read Exchange e-mail from home.

Figure 4. Reading MS Exchange from Linux

Resources

Brian Harvey is currently a UNIX Systems Administrator for U.S. Technical Services in Huntington Beach, CA. He is a graduate of UC Riverside with a BS and MS in Computer Science. He can be reached via email at brian.harvey@ustsvs.com

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vnc is great to use when ur

Anonymous's picture

vnc is great to use when ur loggin into a radio stations on-air computer to run remotely

VPN

Anonymous's picture

VNC is a technology for remote desktop sharing. VNC enables the desktop display of one computer to be remotely viewed and controlled over a network connection. This technology is useful on home computers, allowing someone to access their desktops from another part of the house or while traveling. It is also useful for network administrators in business environments.

VNC was created as an open source research project in the late 1990s. Since that time, several mainstream remote desktop solutions have been created based on VNC. The original development team produces the RealVNC package (see sidebar). Other popular derivatives include UltraVNC and TightVNC.

VNC works similarly to the Remote Desktop appplication built into newer versions of Microsoft Windows. Unlike Windows Remote Desktop, VNC runs on older Windows computers, Linux/Unix and other non-Windows operating systems. VNC applications, however, are generally regarded as slower and offering fewer features and security options than Windows Remote Desktop.

File sharing online,virtual file server storage

computer

Nilam's picture

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