Virtual Network Computing

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Virtual Network ComputingVirtual Network Computing

VNCVNC


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OutlineOutline

• What is VNC?What is VNC?

• Why do we need to be familiar with VNC?Why do we need to be familiar with VNC?

• Where do we get VNC?Where do we get VNC?

• Limitations of VNC?Limitations of VNC?

• Other notes about VNC?Other notes about VNC?


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What is VNC?What is VNC?• Virtual Network Computing (VNC)Virtual Network Computing (VNC)

• Remote control system of other computer Remote control system of other computer windowing environmentswindowing environments

• Allows access to “desktops” of like or Allows access to “desktops” of like or different operating systemsdifferent operating systems

• Developed by AT&T LaboratoriesDeveloped by AT&T Laboratories

• Freely AvailableFreely Available

UNIXUNIX WindowsWindows

MacMac


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Why VNC?Why VNC?• Freedom to choose your favorite computing Freedom to choose your favorite computing

environmentenvironment– And still have access to the more powerful UNIX And still have access to the more powerful UNIX

systemsystem

• Remote access is made possible to the major Remote access is made possible to the major platformsplatforms– You want to work at home, but you forgot that one You want to work at home, but you forgot that one

critical file at school on the…critical file at school on the…

• Reinforces the concepts of client/server Reinforces the concepts of client/server softwaresoftware– Concept foreign to most PC/MAC usersConcept foreign to most PC/MAC users

• Price is rightPrice is right– FreeFree


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Where to get VNC?Where to get VNC?

• AT&T Laboratories, Cambridge UKAT&T Laboratories, Cambridge UKhttp://www.uk.research.att.com/vnc/http://www.uk.research.att.com/vnc/

• Available for UNIX environmentAvailable for UNIX environment– Requires system administrator privilegesRequires system administrator privileges

– Already installed on the CIS machinesAlready installed on the CIS machines

• Available for Windows platformAvailable for Windows platform– Requires you to download and install on your Requires you to download and install on your

machinemachine

• Available for Mac platformAvailable for Mac platform

• Available for Java-enabled browsersAvailable for Java-enabled browsers


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Limitations of VNCLimitations of VNC

• VNC is network resource intensiveVNC is network resource intensive– High Bandwidth connection = Good situationHigh Bandwidth connection = Good situation– Low Bandwidth connection = Bad situationLow Bandwidth connection = Bad situation

• Filesystems are still separate between Filesystems are still separate between different operating systemsdifferent operating systems– Transferring files still requires other mechanisms Transferring files still requires other mechanisms

(e.g. ftp)(e.g. ftp)

• Access to non-Unix platforms do not have Access to non-Unix platforms do not have good multi-user supportgood multi-user support– PC/MAC lack general concept of several user PC/MAC lack general concept of several user

accessaccess


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Quickstart use of VNCQuickstart use of VNC

• PrerequisitesPrerequisites– You should be comfortable with the client/server You should be comfortable with the client/server

concepts of the X-windows environmentconcepts of the X-windows environment– If not, review “Introduction to X windows”If not, review “Introduction to X windows”

» http://www.strath.ac.uk:80/CC/Courses/oldXC/xc.htmlhttp://www.strath.ac.uk:80/CC/Courses/oldXC/xc.html

– VNC server and viewer installed on both local and VNC server and viewer installed on both local and remote machinesremote machines

• Configurations you will encounterConfigurations you will encounter1.1. Local PC/MAC accessing remote UNIX systemLocal PC/MAC accessing remote UNIX system2.2. Local UNIX system accessing remote PC/MACLocal UNIX system accessing remote PC/MAC3.3. Local UNIX system accessing remote UNIX Local UNIX system accessing remote UNIX

systemsystem


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Installation of VNC SoftwareInstallation of VNC Software

• Download siteDownload site– http://www.uk.research.att.com/vnc/download.htmlhttp://www.uk.research.att.com/vnc/download.html

• CIS Unix platformsCIS Unix platforms– Already installed by system administratorAlready installed by system administrator

• PC platformPC platform– Download and install as you would other PC Download and install as you would other PC

softwaresoftware

• Mac platformMac platform– Download and install as you would other Mac Download and install as you would other Mac

softwaresoftware


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VNC Software componentsVNC Software components

• VNC has two major software componentsVNC has two major software components

vncservervncserver

vncviewervncviewer


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VNCSERVERVNCSERVER

• Provides the “remote” half of the “remote Provides the “remote” half of the “remote control” systemcontrol” system

• Communicates interactions from the remote Communicates interactions from the remote machine to the local machinemachine to the local machine

• Exports the view of the remote “deskstop” Exports the view of the remote “deskstop” screen environment to a local machinescreen environment to a local machine

• Imports keyboard and mouse inputs from local Imports keyboard and mouse inputs from local machine to remote machinemachine to remote machine


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VNCVIEWERVNCVIEWER

• Provides the “local” half of the “remote Provides the “local” half of the “remote control” systemcontrol” system

• Communicates interactions between local Communicates interactions between local machine to the remote machinemachine to the remote machine

• Imports the view of the remote “deskstop” Imports the view of the remote “deskstop” screen environment to the local machinescreen environment to the local machine

• Exports keyboard and mouse inputs from local Exports keyboard and mouse inputs from local machine to remote machinemachine to remote machine


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Local PC/Mac Accessing Remote Local PC/Mac Accessing Remote CIS SUN UNIX SystemCIS SUN UNIX System

• PrerequisitesPrerequisites– Assumes you have a UNIX account on CIS systemAssumes you have a UNIX account on CIS system

– Assumes you have downloaded and installed VNC Assumes you have downloaded and installed VNC on your local PC/Macon your local PC/Mac

• Use “telnet” to login to a SUN UNIX systemUse “telnet” to login to a SUN UNIX system% telnet armstrong.cis.rit.edu% telnet armstrong.cis.rit.edu

• Make sure remote machine is a SUN platformMake sure remote machine is a SUN platform% uname -a% uname -a

SunOS armstrong 5.7 ...SunOS armstrong 5.7 ...


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PC/MAC accessing UNIXPC/MAC accessing UNIX(starting server for the first time)(starting server for the first time)• Start the server software on the UNIX side for Start the server software on the UNIX side for

the first time will ask you for a passwordthe first time will ask you for a password% vncserver% vncserver

• This password does not need to be the same This password does not need to be the same as your UNIX passwordas your UNIX password

• This password is used only during This password is used only during authentication when you connect using VNCauthentication when you connect using VNC

• You can change this password using You can change this password using % vncpasswd% vncpasswd


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PC/MAC accessing UNIXPC/MAC accessing UNIX(starting the server)(starting the server)

• Start the server software on the UNIX sideStart the server software on the UNIX side% vncserver% vncserver

New 'X' desktop is armstrong:1New 'X' desktop is armstrong:1

Starting appStarting app...... in ~rvrpci/.vnc/xstartup in ~rvrpci/.vnc/xstartup

Log file is ~rvrpci/.vnc/armstrong:1.logLog file is ~rvrpci/.vnc/armstrong:1.log


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PC/MAC accessing UNIXPC/MAC accessing UNIX(meaning of server messages)(meaning of server messages)

• Name of exported “virtual desktop window” is Name of exported “virtual desktop window” is armstrong:1armstrong:1New 'X' desktop is armstrong:1New 'X' desktop is armstrong:1

• The specific X-window manager and The specific X-window manager and associated startup applications is specified by associated startup applications is specified by the file below (view using text editor)the file below (view using text editor)Starting appStarting app...... in ~rvrpci/.vnc/xstartup in ~rvrpci/.vnc/xstartup

• Any informational or error messages are Any informational or error messages are logged in the file below (view using text editor)logged in the file below (view using text editor)Log file is ~rvrpci/.vnc/armstrong:1.logLog file is ~rvrpci/.vnc/armstrong:1.log


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PC/MAC access UNIXPC/MAC access UNIX(start the viewer)(start the viewer)

• Invoke “vncviewer” applicationInvoke “vncviewer” application– Double click on vncviewer icon or Double click on vncviewer icon or

– ““Start->Programs->VNC->Run VNCviewer”Start->Programs->VNC->Run VNCviewer”

• You will be prompted for a remote host name You will be prompted for a remote host name to controlto control– e.g. e.g. armstrong:1armstrong:1

• You will be prompted for a VNC passwordYou will be prompted for a VNC password

• If successful, you should get a window with a If successful, you should get a window with a viewview


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PC/MAC accessing UNIXPC/MAC accessing UNIX(windows with a view)(windows with a view)


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PC/MAC accessing UNIXPC/MAC accessing UNIX(shutting down the server)(shutting down the server)

% vncserver -kill :1% vncserver -kill :1

Killing Xvnc process ID 10733 Killing Xvnc process ID 10733

• Above command kills the virtual window, in Above command kills the virtual window, in this case, this case, armstrong:1armstrong:1

• If you do not kill the server, but kill the viewer, If you do not kill the server, but kill the viewer, you can always reconnect from another viewer you can always reconnect from another viewer and pick up where you left offand pick up where you left off– Frowned upon by the system administrator if Frowned upon by the system administrator if

abused (SA has prerogative to kill your desktop)abused (SA has prerogative to kill your desktop)


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UNIX accessing PC/MAC DesktopUNIX accessing PC/MAC Desktop

• PrerequisitesPrerequisites– VNC software installed on UNIX and remote VNC software installed on UNIX and remote

PC/MACPC/MAC

– Owner of PC/MAC has given you VNC passwordOwner of PC/MAC has given you VNC password

– Vncserver running on PCVncserver running on PC

• Start vncviewerStart vncviewer% vncviewer% vncviewer

• Enter PC/MAC VNC server name to accessEnter PC/MAC VNC server name to access

• Enter PC/MAC VNC passwordEnter PC/MAC VNC password


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


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UNIX Desktop to UNIX Desktop UNIX Desktop to UNIX Desktop AccessAccess

• Rarely done using VNC because X-windows Rarely done using VNC because X-windows already provides this capabilityalready provides this capability– VNC only adds overheadVNC only adds overhead

• VNC may be used to save desktop VNC may be used to save desktop environments from session to sessionenvironments from session to session

• Procedure similar to PC/MAC to UNIX desktop Procedure similar to PC/MAC to UNIX desktop accessaccess


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PC/MAC to PC/MAC AccessPC/MAC to PC/MAC Access

• Prerequisites similar to PC/MAC to UNIX Prerequisites similar to PC/MAC to UNIX accessaccess

• Be careful interfering with someone working Be careful interfering with someone working on the remote machineon the remote machine– It is possible to disable remote keyboard and It is possible to disable remote keyboard and

mousemouse

• PC to PC access allowsPC to PC access allows– Limited remote troubleshooting of PC systemLimited remote troubleshooting of PC system

–Multiple viewers to “listen in” on one windowMultiple viewers to “listen in” on one window


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Other means of VNC accessOther means of VNC access

• Java-enabled browser can access any Java-enabled browser can access any vncservervncserver

• For example, access to For example, access to armstrong:1armstrong:1http://armstrong:5801http://armstrong:5801

http://armstrong.cis.rit.edu:5801http://armstrong.cis.rit.edu:5801

• Or access to Or access to armstrong:2armstrong:2http://armstrong:5802http://armstrong:5802

http://armstrong.cis.rit.edu:5802http://armstrong.cis.rit.edu:5802

• Successful connection will be followed by Successful connection will be followed by VNC password authentication VNC password authentication


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Browser Access to VNC serverBrowser Access to VNC server


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When in doubt about vncserver When in doubt about vncserver under UNIX…under UNIX…

bean% vncserver -hbean% vncserver -h

usage: vncserver [:<number>] usage: vncserver [:<number>]

[-name <desktop-name>] [-depth <depth>][-name <desktop-name>] [-depth <depth>]

[-geometry <width>x<height>][-geometry <width>x<height>]

[-pixelformat rgbNNN|bgrNNN][-pixelformat rgbNNN|bgrNNN]

<Xvnc-options>...<Xvnc-options>...

vncserver -kill <X-display>vncserver -kill <X-display>


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When in doubt about vncviewer When in doubt about vncviewer under UNIXunder UNIX

bean% vncviewer -hbean% vncviewer -hVNC viewer version 3.3.3r1VNC viewer version 3.3.3r1usage: vncviewer [<options>] <host>:<display#>usage: vncviewer [<options>] <host>:<display#> vncviewer [<options>] -listen [<display#>]vncviewer [<options>] -listen [<display#>]

<options> are standard Xt options, or:<options> are standard Xt options, or: -shared-shared -viewonly-viewonly -fullscreen-fullscreen -passwd <passwd-file>-passwd <passwd-file> -encodings <encoding-list> (e.g. "raw copyrect")-encodings <encoding-list> (e.g. "raw copyrect") -bgr233-bgr233 -owncmap-owncmap -truecolour-truecolour -depth <depth>-depth <depth>


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Key VNC Options to considerKey VNC Options to consider

% vncserver -depth 24% vncserver -depth 24– Starts up your server in 24-bit mode color modeStarts up your server in 24-bit mode color mode

% vncviewer -share -viewonly% vncviewer -share -viewonly– First optionFirst option

» Starts up your viewer so that others can also see the Starts up your viewer so that others can also see the serverserver

» Useful for having two or more people control the desktopUseful for having two or more people control the desktop

– Second optionSecond option» Makes sure that you can only see the desktop and not Makes sure that you can only see the desktop and not

control itcontrol it» Particularly useful in a group environment when you want Particularly useful in a group environment when you want

only one person to “drive”only one person to “drive”


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Other VNC considerationsOther VNC considerations

• Cutting and pasting text informationCutting and pasting text information– Supported between remote and local windowsSupported between remote and local windows

• Provides a foundation for CSCWProvides a foundation for CSCW– Computer Supported Cooperative WorkComputer Supported Cooperative Work

• Source code freely availableSource code freely available– Other platforms are actively being includedOther platforms are actively being included

• VNC performance can be an issue, butVNC performance can be an issue, but– Beats driving through the snow to school to pick up Beats driving through the snow to school to pick up

that one #@$%^ data filethat one #@$%^ data file

Documents

Virtual Network Computing