02-08-2011, 03:29 PM
[attachment=14999]
Virtual Network Computing
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
Where to get VNC?
AT&T Laboratories, Cambridge UK
http://uk.research.attvnc/
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
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
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://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
Installation of VNC Software
Download site
http://uk.research.attvnc/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
VNC Software components
VNC has two major software components
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
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
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 ...
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
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
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
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
PC/MAC accessing UNIX (windows with a view)
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)
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
UNIX accessing PC/MAC Desktop (X-windows with a view)
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
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
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
Browser Access to VNC server
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>
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>
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”
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
Virtual Network Computing
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
Where to get VNC?
AT&T Laboratories, Cambridge UK
http://uk.research.attvnc/
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
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
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://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
Installation of VNC Software
Download site
http://uk.research.attvnc/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
VNC Software components
VNC has two major software components
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
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
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 ...
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
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
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
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
PC/MAC accessing UNIX (windows with a view)
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)
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
UNIX accessing PC/MAC Desktop (X-windows with a view)
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
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
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
Browser Access to VNC server
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>
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>
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”
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
