LinuxNetMag
VNC -- WINDOWS under control
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LinuxNetMag #3

  Software
 MP3
Xaudio, xmms, mp3blaster
freeztag, kmp3te
 Games
TTY-Quake, Quake3Test
Descent, LDescent, DX1
Flightsimulators
 Applications
Wine: Installation and Setup
VCron, Kcrontab
Passwords with Gpasman
 Misc.
Bootlogos: Welcome2L...
[email protected] and tools
Lightspeed
  
 

Network

Alternative Web-Browser
Linpopup
VNC - Windows X-Server
Fetchmail Part II
Apache the webserver
Windows networks: Samba
Webpublishing: Sitecopy
downloadhelp Wget
Webalizer
recommended links
  
 

Hardware

HD-/Floppy- Access
Jslaunch
  
 

Misc.

Editorial
Guestbook
Mailingliste
Complete list of articles



printer-version


 
VNC

Administrate WINDOWS and be far away? Work with WINDOWS or a Mac under Linux? Every PC is able to be steered by any other? You think this is a dream every administrator of heterogeneous networks does have?
VNC combines all operating systems. And it is free!



 
Do you see my WINDOWS through this window?

With VNC (Virtual Network Computing) you are able to remote control another PC inside a network. You see the same desktop as if you were sitting in front of it. This does not just work between Linux machines but also between WINDOWS and any other combination of WINDOWS, Linux and MacOs computers.
The times are over when you had to leave your PC in case of trouble somewhere else. As long as a network connection exists you are able to have a look at this PC and help the user from your working place. Also software updates over the net are possible.
The best use for us would be the ability to work on a Linux machine if you were sitting in front of a WINDOWs - PC. Of course you need at least one Linux system inside the network where you have access on.
 
 

Server and Viewer

VNC own two programs, the viewer (vncviewer) and the server (vncserver). The server has to be started on the computer that you want to access and the viewer on the PC where you want to work at. If you want to administrate the computers inside the network all over you need the server and viewer for the different platforms. The viewer is also available as a Java version and you just need a web browser that supports it. Until now you have been able to use VNC with the following operation systems:

  • Solaris 2.5 (Sparc)
  • Linux 2.0 for x86
  • DEC Alpha OSF13.2
  • Windows 32
  • Macintosh
  • Windows CE
These version are all free available at http://www.uk.research.att.com/vnc/
 
 
Installation under Linux

If you use a SUSE system you should install the included rpm package vnc.rpm . Other distribution have to download the source or the pre compiled versions if it is not included. You get the necessary packages at http://www.uk.research.att.com/vnc/ download.html. After installing the software you start at server with

>> vncserver
To increase the security you should never start the server as root only as a normal user. Later you can get root access via su in a xterm.
During the first starting of vncserver a password is wanted that restricts any access later. The server is started as a deamon and needs few CPU power. 
Linux supports more than one X-server. Does already one X-server run it gets the ID "localhost:1", in this case the vncserver starts a new X-server using ":2" if this number is free. The standard output prompts the following message:
"New 'X' desktop is paul:2"
You need this port number to build a connection with vncviewer to the server. As a first try you should start vncviewer at the same computer as the server runs
>> vncviewer localhost:2
and the number corresponds to the port that was activated with vncserver.
Now it asks for the password and then a window opens. In this one a usual X-server appears with a windowmanager (default twm) and a terminal. The configuration which program are started is set in the file ~/.vnc/xstartup . These programs are started after logging in with vncviewer. The last entry start the windowmanager. If you own a slow network connection you should keep it as it is. If you still have free resources you could choose a bigger on like WindowMaker or KDE.
 
 
Installation under WINDOWS

On WINDOWS the installation runs as usually. After downloading and decompression the files you are able to use the viewer at once without any installation procedure. The vncserver has to be installed before.
To access the Linux PC from WINDOWs you start vncviewer and enter in the appearing window the IP address (or host name) of the Linux computer and the port number of the X-server. There are just few programs (like xfmail) that do not want to work but the most programs do not notice that they are displayed somewhere else.
If you want to steer the WINDOWS-PC from your Linux machine you have to start the vncserver on WINDOWS. Then you access this PC with vncviewer from Linux entering the IP and port 1 and you have full control over it. The password is set with he vncserver on WINDOWS.
 
 

Automatic start

At Linux you should not start the vncserver automatically during booting because any access to the Linux PC is then just saved by this vnc password. It is much safer to start the server on the Linux PC by your own logging in from outside (if possible with secure shell, ssh) and stop it after closing the viewer at the end of the session. It is recommended to use different passwords for vnc and your normal login.
At WINDOWS you can start the vncserver every time during booting without any risk because the security leak is already big enough. Therefore you create a link to the server in the autostart folder.
 
 

Velocity

X-Windows (XFree86) has been designed and optimized to be used inside networks from the beginning of its development and needs few network resources. WINDOWS was not designed to produce low traffic and the vncserver works very hard to submit all data to the Linux PC. That is why the window handling is quite slow. If you control a Linux session from WINDOWS you will see it is much faster. In addition it is possible to use more than one X-server and many people can work on one computer at the same time.
 
 

Java support

The greatest independence of VNC was reached as they presented a java version. Since then it has been possible to remote control from any OS. The only thing that is needed is a web browser that supports Java. Instead of the vncviewer the browser contacts the server. Just enter the site http://IP_Number:5801 . The IP number chooses the PC where the server runs and the last port number corresponds to the X-server that was started. A very fast computer is recommended because the screen display happens with Java and takes much CPU resources. You are able to accelerate the presentation if you do not use a pixmap in the background just a one color windowmanager. You reach this with the command

>> xsetroot -solid white
 
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