The VNC program is an application that will run an X-windows graphic interface on the Genomics computers.   Actually VNC can be used to communication between a variety of computers -- PC to UNIX, PC to PC, Mac to PC, Unix to PC, etc. -- and it can be useful to control remote PCs and Macs in addition to connecting to the Genomics center.  See the VNC web site for more information.

    X-windows (and thus VNC) is required for using graphical programs such as Consed. It can also be used for graphical file manipulation. However if you are just going to do simple command line work then using a secure shell (SSH) program will probably work just as well and is more simple to set up.

    The VNC viewer for PCs is a simple program available here.  There are also newer (and also free) viewers available on the VNC web site mentioned above. Mac people can use a program called Chicken of the VNC; there is at least one other viewer available as well.

    Once you have VNC installed on your computer then, once you run it, it will ask for where you wish to connect.  You can connect to either any of the Genomics center computers via ports 50 through 59.  Ports 50 through 54 are the 'normal' ones.  Ports 55 through 59 are for applications that require only 8-bit color. The various ports differ only in the size of the screen you will connect to:
 

    Most people will probably use port 51 or 52 although if you have a large monitor the other ports would be nice.  Examples of the actual connect commands:

   silverjack.genomics.purdue.edu:52
   fermat.genomics.purdue.edu:51
   sapporo.genomics.purdue.edu:59

   Once VNC connects you to the Genomics computers you will be presented with a login screen.  The first time you use this login screen make sure that the 'options' 'session' button is marked as 'CDE' (common desktop environment) although if you are comfortable with some of the other environments (KDE, Gnome, OpenWindows) then you should use these.  This is a one-time-only setting; later uses of VNC should default to your last chosen environment.

   Once logged into the center you will see the CDE or whatever other environment you may have chosen.  At this point the complexity and flexibility of UNIX becomes evident and it becomes hard to describe everything that can be done.  One major task people will often want to do is to start up a simple terminal session.  For the CDE in the right part of the task bar will be an option named 'hosts' (it looks like colored bars).  Click on this to open it up and then choose a 'console' session.  From this you can run a variety of programs.

   One item that throws a lot of Mac and PC users off is Unix's (actually X-window's) use of a three button mouse.  Occasionally an X-windows program will require this middle button.  For the PC running VNC holding down both buttons simultaneously will send a 'third button' signal to Unix.  On the Mac running VNC the second and third buttons are emulated via the use of keys plus the mouse -- see the VNC help screen.

   That is about it.  As mentioned, Unix and X-windows are very powerful but also complex.  Call/email the genomics sysadmin (Doug at gadmin@purdue.edu) if you have further questions.

Off-campus or secure use

      If you want to use VNC from off-campus then you must use a secure method (SSH) to connect to the Genomics servers. Using a secure method is recommended even if you are on the Purdue campus since it is, in theory, possible that your VNC session could be intercepted by other people. As of 2005 Purdue now recommends that everyone use secure methods in all of their programs -- email, VNC, command line connections, etc. -- and thus it is a good idea to get in the habit of doing everything through SSH.

      To make a secure VNC connection you must first be able to log into a genomic machine using a SSH client such as PuTTY or SecureCRT (available via the ITaP security web site; installation instructions.) Also see the get access page for other options.) Using an SSH client is the normal way to get a command line prompt on the genomics servers. For VNC you need to add an extra layer on top of this normal method. Set up Putty or your preferred SSH program to "tunnel" the "source" port "5951" (or other number between 50 to 59) to your "destination" port "localhost:5951" (or other number.) How to do this will vary between different programs but should be straight-forward. Once you have the tunneling set up in your program then use the program to connect to and log into a genomics machine as normal.

      Start up VNC and instead of the normal 'silverjack.genomics.purdue.edu:51' type in:

      localhost:51

      Obviously if you want to go to a different port (e.g., 53) then use that number. Also make sure that your tunnel includes that port which, for SSH, has a '59' pre-pended to it (e.g., 5953).

      What happens at this point is that VNC (port 51) talks to your PC's local port 5951 which then talks to the SSH connection you have which then tunnels your VNC connection to the genomics server in a secure manner. It sounds complex however once you have everything set up then it works seamlessly ... and securely.

      As a note, one person who set this up writes, "The putty and VNC combination works fine however I had to modify the process. The VNC version needs to be 4 or higher for windowXP. The connect command for VNC was not localhost:52 but silverjack.genomics.purdue.edu:52."