Fall 2008
- Mon, Sep 8, 4pm, Math 101, Remote Connection, SSH, and VNC, by Joe McMahon
- Mon, Sep 15, 4pm, Math 102, An introduction to LaTeX and Beamer, by Kevin LaTourette
- Mon, Oct 13, 4pm, Math 101, Paradigm Shifts in Science Based Simulations, by Mac Hyman
For more details, and talks in past semesters, consult the
full schedule of talks.
Tentative talks:
- Math on a MAC
- How to deal with e-mail spam
- Scripting with Bash
- Power Point presentation using LaTeX
- GNU/Linux text editors
Interested in speaking?
Past topics can (and should) be repeated
occasionally. In addition,
here are some topics people might like to hear about:
- Femlab (PDE modeling environment)
- GAP (computer algebra software)
- Getting started with Maple (or Matlab, or Mathematica, ...)
- How to do math on a Mac
- How to filter e-mail spam
- HTML vs. XHTML (the new HTML standard)
- Octave (free Matlab-like system)
- PDAs (handheld personal digital assistants and much more)
- PHP (server-side webpage scripting)
- R (free statistics system)
- Remote access (SSH, VNC, dial-up, ...)
- Scientific WorkPlace (graphical front end to TeX)
- Setting up a dual boot system (DOS/Linux)
- TeX / LaTeX topics
- Using scanners efficiently
- Using the WINEDT editor (a front end to TeX, HTML)
- XML (extensible markup language)
- [your favorite topic here]
To give a talk, please contact
swig@math.arizona.edu.
VNC, SSH & more: an idiot's guide
by Daniel Reich (Fall 2006)
Below you will find detailed instructions on using vnc to access your remote desktop. Important: grad students must substitute iguana.math.arizona.edu and faculty/staff must substitute bobcat.math.arizona.edu for vncserver in all commands below. Also, substitute your math network username for username.
Setting up your VNC account:
Before you vnc for the first time, you must set up your vnc account:
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How you connect depends on your operating system. In linux/mac, open the terminal and type ssh username@vncserver. In windows, open your favorite SSH client (e.g. putty) and enter vncserver for Host Name and your math account username and password. You should now be connected to vncserver.
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Once connected, type vncserver. You will be asked to choose a new password for vnc (which we'll refer to as vncpassword). Since vnc is not a secure connection, it is not advisable to use the same password as you use for your math account. After entering vncpassword, you will be given a number for your remote desktop (which we will refer to as number). Remember this number. If you forget it, you will have to kill your desktop and start a new one (details can be found below).
Using VNC:
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In linux/mac, open the terminal and type vncviewer vncserver:number. In windows open your vncviewer application (e.g. TightVNC Viewer) and enter vncserver:number. When prompted, enter vncpassword (not to be confused with your math account password).
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You can now use the screen in front of you just like you would if you were sitting in front of a linux computer in the math building. However, it is inadvisable to do heavy-duty computations e.g. using maple matlab or mathematica since bobcat and iguana are shared gateway systems that need to remain available for all members of the department. For instructions on the latter, see below for "Heavy Duty Computations".
Killing desktops and starting new ones
Here's how to kill remote desktops and start new ones (below you will find examples of why you might want to do this):
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SSH into VNCSERVER (see "Setting up your VNC account" above).
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To kill all your existing desktops, type killall Xrealvnc. To kill just one, type vncserver -kill :number. Note: if you try to kill all desktops, you will receive "Operation Not Permitted" error messages, which can be ignored. These error messages are due to your inability to close desktops owned by other users.
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To start a new desktop, type vncserver. Remember your new remote desktop number (which may end up being the same as your old one).
Controlling size & appearance:
You may find yourself looking at the screen and wishing, for example, that your VNC viewer window had a different size. There is no way to change such server-side properties of an existing desktop. Instead, the existing desktop can be killed and one can start a new one.
Below is an example of how to create a remote desktop with a resolution of 1024x768 with a color depth of 8 bits per pixel. If you want a different resolution and color depth, change the values accordingly.
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SSH into vncserver (see "Setting up your VNC account" above).
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If you like, kill your existing desktops (see "Killing desktops and starting new ones" above).
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Type vncserver -geometry 1024x768 -depth 8. Remember number. Note: geometry and depth are examples of advanced setting options. For other advanced setting options, consult the man page for vncserver by typing man vncserver.
Heavy Duty Computations
One way to run a specific application remotely via a local GUI is to use the X Windows port forwarding feature of SSH. Below, is an example of how to run matlab on the chivo cluster (for gradstudents) in this fashion.
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Open a VNC connection (see "Using VNC" above).
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Open the terminal (click Applications and go to Accessories).
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Type ssh -Y chivo1. When prompted, enter your math account password.
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Type matlab. Note: if you close the terminal, you will kill matlab.
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Important: In VNC your remote desktop is there whether you are using it or not, so you may close the vnc client and then open it up without ending the SSH session with chivo1 (or any other windows open on your desktop for that matter).
VNC: a more secure approach
The VNC protocol itself does not securely encrypt the connection. However, it can be made more secure by using the general port forwarding feature of SSH. To accomplish this you will use your number, as it is shorthand for the port on which your remote desktop can be accessed. In fact, by adding 5900 to number, you obtain your portnumber for your remote desktop, e.g. if number is 5, then portnumber is 5905.
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In linux/mac, type ssh username@vncserver -L 12345:localhost:portnumber. This tells SSH to listen on port 12345 of your computer and send everthing on port 12345 to portnumber on vncserver. Note: localhost always refers to the computer you are currently on, e.g. localhost on iguana is iguana and localhost on your home computer is your home computer. Therefore, in the command above since we are connecting to vncserver, localhost refers to vncserver.
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In linux/ mac, open a second terminal window (so that your SSH connection remains open) and type vncviewer localhost:12345 (since this window is on your home computer, localhost refers to your home computer). This command opens a session of vncviewer on your home computer port 12345, which is then directed via SSH to vncserver.
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In windows, open putty and enter vncserver. Under category "SSH", click "Tunnels". For "Source Port" enter 12345 and for "Destination" enter localhost:portnumber. Click "Add" then "Open". This tells SSH to listen on port 12345 of your computer and send everthing on port 12345 to portnumber on vncserver. Note: localhost always refers to the computer you are currently on, e.g. localhost on iguana is iguana and localhost on your home computer is your home computer. Therefore, in the command above since we are connecting to vncserver, localhost refers to vncserver.
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In windows, open your vncviewer application and type localhost::12345 (since this window is on your home computer, localhost refers to your home computer). This command opens a session of vncviewer on your home computer port 12345, which is then directed via SSH to vncserver.
