Virtual Network Computing

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Virtual Network Computing

• VNC

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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?

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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 ATT Laboratories
• Freely Available

UNIX
Windows
Mac
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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

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Where to get VNC?

• ATT 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

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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

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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.uk80/CC/Courses/oldXC/xc.htm
  l
• 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

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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

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VNC Software components

• VNC has two major software components

• Remote

vncserver

• Local

vncviewer
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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

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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

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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 ...

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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

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PC/MAC accessing UNIX(starting the server)

• Start the server software on the UNIX side
• vncserver
• New 'X' desktop is armstrong1
• Starting app... in rvrpci/.vnc/xstartup
• Log file is rvrpci/.vnc/armstrong1.log

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PC/MAC accessing UNIX(meaning of server messages)

• Name of exported virtual desktop window is
  armstrong1
• New 'X' desktop is armstrong1
• 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/armstrong1.log

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PC/MAC access UNIX(start the viewer)

• Invoke vncviewer application
• Double click on vncviewer icon or
• Start-gtPrograms-gtVNC-gtRun VNCviewer
• You will be prompted for a remote host name to
  control
• e.g. armstrong1
• You will be prompted for a VNC password
• If successful, you should get a window with a
  view

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PC/MAC accessing UNIX(windows with a view)
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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, armstrong1
• 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)

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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

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

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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

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Other means of VNC access

• Java-enabled browser can access any vncserver
• For example, access to armstrong1
• http//armstrong5801
• http//armstrong.cis.rit.edu5801
• Or access to armstrong2
• http//armstrong5802
• http//armstrong.cis.rit.edu5802
• Successful connection will be followed by VNC
  password authentication

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Browser Access to VNC server
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When in doubt about vncserver under UNIX

• bean vncserver -h
• usage vncserver ltnumbergt
• -name ltdesktop-namegt -depth ltdepthgt
• -geometry ltwidthgtxltheightgt
• -pixelformat rgbNNNbgrNNN
• ltXvnc-optionsgt...
• vncserver -kill ltX-displaygt

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When in doubt about vncviewer under UNIX

• bean vncviewer -h
• VNC viewer version 3.3.3r1
• usage vncviewer ltoptionsgt lthostgtltdisplaygt
• vncviewer ltoptionsgt -listen ltdisplaygt
• ltoptionsgt are standard Xt options, or
• -shared
• -viewonly
• -fullscreen
• -passwd ltpasswd-filegt
• -encodings ltencoding-listgt (e.g. "raw
  copyrect")
• -bgr233
• -owncmap
• -truecolour
• -depth ltdepthgt

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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

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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 _at_ data file