Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 1 Virtual Network Computing VNC

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 2 Outline 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?

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 3 What is VNC? Virtual Network Computing (VNC)Virtual Network Computing (VNC) Remote control system of other computer windowing environmentsRemote control system of other computer windowing environments Allows access to “desktops” of like or different operating systemsAllows access to “desktops” of like or different operating systems Developed by AT&T LaboratoriesDeveloped by AT&T Laboratories Freely AvailableFreely Available UNIX Windows Mac

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 4 Why VNC? Freedom to choose your favorite computing environmentFreedom to choose your favorite computing environment –And still have access to the more powerful UNIX system Remote access is made possible to the major platformsRemote 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 softwareReinforces the concepts of client/server software –Concept foreign to most PC/MAC users Price is rightPrice is right –Free

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 5 Where to get VNC? AT&T Laboratories, Cambridge UKAT&T Laboratories, Cambridge UK Available for UNIX environmentAvailable for UNIX environment –Requires system administrator privileges –Already installed on the CIS machines Available for Windows platformAvailable for Windows platform –Requires you to download and install on your machine Available for Mac platformAvailable for Mac platform Available for Java-enabled browsersAvailable for Java-enabled browsers

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 6 Other VNC Implementations TightVNC ( ( RealVNC ( ( Limited alternativeLimited alternative –Microsoft Windows »“Remote Desktop Connection” »BUT ONLY TO WINDOWS MACHINES

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 7 Limitations of VNC VNC is network resource intensiveVNC is network resource intensive –High Bandwidth connection = Good situation –Low Bandwidth connection = Bad situation Filesystems are still separate between different OSFilesystems are still separate between different OS –Transferring files still requires other mechanisms (e.g. scp, ftp) Access to non-Unix platforms do not have good multi- user supportAccess to non-Unix platforms do not have good multi- user support –PC/MAC lack general concept of several user access Security an issueSecurity an issue

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 8 Quickstart use of VNC PrerequisitesPrerequisites –You should be comfortable with the client/server concepts of the X-windows environment –If not, review “Introduction to X windows” » –VNC server and viewer installed on both local and remote machines Configurations you will encounterConfigurations you will encounter 1.Local PC/MAC accessing remote UNIX system 2.Local UNIX system accessing remote PC/MAC 3.Local UNIX system accessing remote UNIX system

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 9 Installation of VNC Software Download siteDownload site – CIS Unix platformsCIS Unix platforms –Already installed by system administrator PC platformPC platform –Download and install as you would other PC software Mac platformMac platform –Download and install as you would other Mac software

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 10 VNC Software components VNC has two major software componentsVNC has two major software components vncserver vncviewer

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 11 VNCSERVER Provides the “remote” half of the “remote control” systemProvides the “remote” half of the “remote control” system Communicates interactions from the remote machine to the local machineCommunicates interactions from the remote machine to the local machine Exports the view of the remote “deskstop” screen environment to a local machineExports the view of the remote “deskstop” screen environment to a local machine Imports keyboard and mouse inputs from local machine to remote machineImports keyboard and mouse inputs from local machine to remote machine

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 12 VNCVIEWER Provides the “local” half of the “remote control” systemProvides the “local” half of the “remote control” system Communicates interactions between local machine to the remote machineCommunicates interactions between local machine to the remote machine Imports the view of the remote “deskstop” screen environment to the local machineImports the view of the remote “deskstop” screen environment to the local machine Exports keyboard and mouse inputs from local machine to remote machineExports keyboard and mouse inputs from local machine to remote machine

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 13 Local PC/Mac Accessing Remote CIS SUN UNIX System PrerequisitesPrerequisites –Assumes you have a UNIX account on CIS system –Assumes you have downloaded and installed VNC on your local PC/Mac Use “ssh” to login to a SUN UNIX systemUse “ssh” to login to a SUN UNIX system % ssh armstrong.cis.rit.edu Make sure remote machine is a SUN platformMake sure remote machine is a SUN platform % uname -a SunOS armstrong

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 14 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 passwordStart the server software on the UNIX side for the first time will ask you for a password % vncserver –depth 24 This password does not need to be the same as your UNIX passwordThis password does not need to be the same as your UNIX password This password is used only during authentication when you connect using VNCThis password is used only during authentication when you connect using VNC You can change this password usingYou can change this password using % vncpasswd

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 15 PC/MAC accessing UNIX (starting the server) Start the server software on the UNIX sideStart the server software on the UNIX side % vncserver –depth 24 New 'X' desktop is armstrong:1 Starting app... in ~rvrpci/.vnc/xstartup Log file is ~rvrpci/.vnc/armstrong:1.log

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 16 PC/MAC accessing UNIX (meaning of server messages) Name of exported “virtual desktop window” is armstrong:1Name 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)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)Any informational or error messages are logged in the file below (view using text editor) Log file is ~rvrpci/.vnc/armstrong:1.log

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 17 PC/MAC access UNIX (start the viewer) Invoke “vncviewer” applicationInvoke “vncviewer” application –Double click on vncviewer icon or –“Start->Programs->VNC->Run VNCviewer” You will be prompted for a remote host name to controlYou will be prompted for a remote host name to control –e.g. armstrong: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 viewIf successful, you should get a window with a view

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 18 PC/MAC accessing UNIX (windows with a view)

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 19 PC/MAC accessing UNIX (shutting down the server) % vncserver -kill :1 Killing Xvnc process ID Above command kills the virtual window, in this case, armstrong:1Above 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 offIf 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)

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 20 UNIX accessing PC/MAC Desktop PrerequisitesPrerequisites –VNC software installed on UNIX and remote PC/MAC –Owner of PC/MAC has given you VNC password –Vncserver running on PC Start vncviewerStart 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

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 21 UNIX accessing PC/MAC Desktop (X-windows with a view)

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 22 UNIX Desktop to UNIX Desktop Access Rarely done using VNC because X-windows already provides this capabilityRarely 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 sessionVNC may be used to save desktop environments from session to session Procedure similar to PC/MAC to UNIX desktop accessProcedure similar to PC/MAC to UNIX desktop access

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 23 PC/MAC to PC/MAC Access Prerequisites similar to PC/MAC to UNIX accessPrerequisites similar to PC/MAC to UNIX access Be careful interfering with someone working on the remote machineBe careful interfering with someone working on the remote machine –It is possible to disable remote keyboard and mouse PC to PC access allowsPC to PC access allows –Limited remote troubleshooting of PC system –Multiple viewers to “listen in” on one window

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 24 Other means of VNC access Java-enabled browser can access any vncserverJava-enabled browser can access any vncserver For example, access to armstrong:1For example, access to armstrong:1 Or access to armstrong:2Or access to armstrong:2 Successful connection will be followed by VNC password authenticationSuccessful connection will be followed by VNC password authentication

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 25 Browser Access to VNC server

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 26 When in doubt about vncserver under UNIX… bean% vncserver -h usage: vncserver [: ] [-name ] [-depth ] [-geometry x ] [-geometry x ] [-pixelformat rgbNNN|bgrNNN] [-pixelformat rgbNNN|bgrNNN] vncserver -kill vncserver -kill

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 27 When in doubt about vncviewer under UNIX bean% vncviewer -h VNC viewer version 3.3.3r1 usage: vncviewer [ ] : usage: vncviewer [ ] : vncviewer [ ] -listen [ ] vncviewer [ ] -listen [ ] are standard Xt options, or: are standard Xt options, or: -shared -shared -viewonly -viewonly -fullscreen -fullscreen -passwd -passwd -encodings (e.g. "raw copyrect") -encodings (e.g. "raw copyrect") -bgr233 -bgr233 -owncmap -owncmap -truecolour -truecolour -depth -depth

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 28 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”

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 29 Customizing VNC window managers Edit the following fileEdit the following file~/.vnc/xstartup Edit line specifying the window managerEdit line specifying the window manager twm & or ctwm & Change to your favorite window manager, e.g.Change to your favorite window manager, e.g. /usr/dt/bin/dtwm & or gnome-session & for CDE and GNOME environments, respectively

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 30 Other VNC considerations Cutting and pasting text informationCutting and pasting text information –Supported between remote and local windows Provides a foundation for CSCWProvides a foundation for CSCW –Computer Supported Cooperative Work Source code freely availableSource code freely available –Other 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 that one data file

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 31 Security Issues We will address some security issuesWe will address some security issues –Use of SSH (Secure Shell) –Use of Tunnelling through SSH

Digital Imaging and Remote Sensing Laboratory R.I.TR.I.TR.I.TR.I.T R.I.TR.I.TR.I.TR.I.T 32 How about File Transfer? Use scp (secure copy) to transfer from PC to UNIX (and back if necessary)Use scp (secure copy) to transfer from PC to UNIX (and back if necessary) –Very secure file transfer You can use the wiki as a repository of filesYou can use the wiki as a repository of files –Good for archiving –Cumbersome for many files unless zipped –Need to be aware of access control Use FolderShare (basic application is free)Use FolderShare (basic application is free) –Conveniently synchronizes specific folders between PC/MACS –You have a desktop at home and you have a laptop at work/school