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Virtual Network Computing

Virtual Network Computing. VNC. Outline. What is VNC? Why do we need to be familiar with VNC? Where do we get VNC? Limitations of VNC? Other notes about VNC?. What is VNC?. Virtual Network Computing (VNC) Remote control system of other computer windowing environments

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Virtual Network Computing

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  1. Virtual Network Computing VNC

  2. Outline • What is VNC? • Why do we need to be familiar with VNC? • Where do we get VNC? • Limitations of VNC? • Other notes about VNC?

  3. What is VNC? • Virtual Network Computing (VNC) • Remote control system of other computer windowing environments • Allows access to “desktops” of like or different operating systems • Developed by AT&T Laboratories • Freely Available UNIX Windows Mac

  4. Why VNC? • Freedom to choose your favorite computing environment • And still have access to the more powerful UNIX system • Remote access is made possible to the major platforms • You want to work at home, but you forgot that one critical file at school on the… • Reinforces the concepts of client/server software • Concept foreign to most PC/MAC users • Price is right • Free

  5. Where to get VNC? • AT&T Laboratories, Cambridge UK http://www.uk.research.att.com/vnc/ • Available for UNIX environment • Requires system administrator privileges • Already installed on the CIS machines • Available for Windows platform • Requires you to download and install on your machine • Available for Mac platform • Available for Java-enabled browsers

  6. Limitations of VNC • VNC is network resource intensive • High Bandwidth connection = Good situation • Low Bandwidth connection = Bad situation • Filesystems are still separate between different operating systems • Transferring files still requires other mechanisms (e.g. ftp) • Access to non-Unix platforms do not have good multi-user support • PC/MAC lack general concept of several user access

  7. Quickstart use of VNC • Prerequisites • You should be comfortable with the client/server concepts of the X-windows environment • If not, review “Introduction to X windows” • http://www.strath.ac.uk:80/CC/Courses/oldXC/xc.html • VNC server and viewer installed on both local and remote machines • Configurations you will encounter • Local PC/MAC accessing remote UNIX system • Local UNIX system accessing remote PC/MAC • Local UNIX system accessing remote UNIX system

  8. Installation of VNC Software • Download site • http://www.uk.research.att.com/vnc/download.html • CIS Unix platforms • Already installed by system administrator • PC platform • Download and install as you would other PC software • Mac platform • Download and install as you would other Mac software

  9. VNC Software components • VNC has two major software components Remote vncserver Local vncviewer

  10. VNCSERVER • Provides the “remote” half of the “remote control” system • Communicates interactions from the remote machine to the local machine • Exports the view of the remote “deskstop” screen environment to a local machine • Imports keyboard and mouse inputs from local machine to remote machine

  11. VNCVIEWER • Provides the “local” half of the “remote control” system • Communicates interactions between local machine to the remote machine • Imports the view of the remote “deskstop” screen environment to the local machine • Exports keyboard and mouse inputs from local machine to remote machine

  12. Local PC/Mac Accessing Remote CIS SUN UNIX System • Prerequisites • Assumes you have a UNIX account on CIS system • Assumes you have downloaded and installed VNC on your local PC/Mac • Use “telnet” to login to a SUN UNIX system % telnet armstrong.cis.rit.edu • Make sure remote machine is a SUN platform % uname -a SunOS armstrong 5.7 ...

  13. PC/MAC accessing UNIX(starting server for the first time) • Start the server software on the UNIX side for the first time will ask you for a password % vncserver • This password does not need to be the same as your UNIX password • This password is used only during authentication when you connect using VNC • You can change this password using % vncpasswd

  14. PC/MAC accessing UNIX(starting the server) • Start the server software on the UNIX side % vncserver New 'X' desktop is armstrong:1 Starting app... in ~rvrpci/.vnc/xstartup Log file is ~rvrpci/.vnc/armstrong:1.log

  15. PC/MAC accessing UNIX(meaning of server messages) • Name of exported “virtual desktop window” is armstrong:1 New 'X' desktop is armstrong:1 • The specific X-window manager and associated startup applications is specified by the file below (view using text editor) Starting app... in ~rvrpci/.vnc/xstartup • Any informational or error messages are logged in the file below (view using text editor) Log file is ~rvrpci/.vnc/armstrong:1.log

  16. PC/MAC access UNIX(start the viewer) • Invoke “vncviewer” application • Double click on vncviewer icon or • “Start->Programs->VNC->Run VNCviewer” • You will be prompted for a remote host name to control • e.g. armstrong:1 • You will be prompted for a VNC password • If successful, you should get a window with a view

  17. PC/MAC accessing UNIX(windows with a view)

  18. PC/MAC accessing UNIX(shutting down the server) % vncserver -kill :1 Killing Xvnc process ID 10733 • Above command kills the virtual window, in this case, armstrong:1 • If you do not kill the server, but kill the viewer, you can always reconnect from another viewer and pick up where you left off • Frowned upon by the system administrator if abused (SA has prerogative to kill your desktop)

  19. UNIX accessing PC/MAC Desktop • Prerequisites • VNC software installed on UNIX and remote PC/MAC • Owner of PC/MAC has given you VNC password • Vncserver running on PC • Start vncviewer % vncviewer • Enter PC/MAC VNC server name to access • Enter PC/MAC VNC password

  20. UNIX accessing PC/MAC Desktop(X-windows with a view)

  21. UNIX Desktop to UNIX Desktop Access • Rarely done using VNC because X-windows already provides this capability • VNC only adds overhead • VNC may be used to save desktop environments from session to session • Procedure similar to PC/MAC to UNIX desktop access

  22. PC/MAC to PC/MAC Access • Prerequisites similar to PC/MAC to UNIX access • Be careful interfering with someone working on the remote machine • It is possible to disable remote keyboard and mouse • PC to PC access allows • Limited remote troubleshooting of PC system • Multiple viewers to “listen in” on one window

  23. Other means of VNC access • Java-enabled browser can access any vncserver • For example, access to armstrong:1 http://armstrong:5801 http://armstrong.cis.rit.edu:5801 • Or access to armstrong:2 http://armstrong:5802 http://armstrong.cis.rit.edu:5802 • Successful connection will be followed by VNC password authentication

  24. Browser Access to VNC server

  25. When in doubt about vncserver under UNIX… bean% vncserver -h usage: vncserver [:<number>] [-name <desktop-name>] [-depth <depth>] [-geometry <width>x<height>] [-pixelformat rgbNNN|bgrNNN] <Xvnc-options>... vncserver -kill <X-display>

  26. When in doubt about vncviewer under UNIX bean% vncviewer -h VNC viewer version 3.3.3r1 usage: vncviewer [<options>] <host>:<display#> vncviewer [<options>] -listen [<display#>] <options> are standard Xt options, or: -shared -viewonly -fullscreen -passwd <passwd-file> -encodings <encoding-list> (e.g. "raw copyrect") -bgr233 -owncmap -truecolour -depth <depth>

  27. Key VNC Options to consider % vncserver -depth 24 • Starts up your server in 24-bit mode color mode % vncviewer -share -viewonly • First option • Starts up your viewer so that others can also see the server • Useful for having two or more people control the desktop • Second option • Makes sure that you can only see the desktop and not control it • Particularly useful in a group environment when you want only one person to “drive”

  28. Other VNC considerations • Cutting and pasting text information • Supported between remote and local windows • Provides a foundation for CSCW • Computer Supported Cooperative Work • Source code freely available • Other platforms are actively being included • VNC performance can be an issue, but • Beats driving through the snow to school to pick up that one #@$%^ data file

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