HMC Mathematics Computing Weblog

We have taken delivery of a new color printer, gaspode, a Hewlett Packard Color LaserJet 5550dtn.

This printer was a gift from Hewlett Packard and its Hardcopy Technologies Lab's director, John Meyer. We would not have received this generous gift without the work of Professor Mike Raugh, our department's Clinic Director.

gaspode replaces winter, our Minolta-QMS magiColor 6100. The new printer is much faster (up to 27 pages per minute in black and white or color) and uses HP's imageRET technology to achieve resolutions of up to 3600 dpi.

Information on printing to the new printer is available on our math computing support website. (Please use this link, as this information is not yet tied into the site as a whole; I expect to create similar pages for each printer in the near future.)

Please thank Mike Raugh for obtaining this printer for the department.

CNet's news.com's Stephen Shankland has an article on RHEL rebuilds. (I'm quoted!)

I have updated the versions of Sun's Java Software Devlopment Kits (SDKs) to the latest versions -- 1.4.2_07 and 1.5.0_02. The permission-elevation problem in the 1.4.2 series is addressed in the 07 update.

The standard Java remains 1.4.2. To use Java 5 (really 1.5), you will have to run the binaries by typing their full pathnames or add the Java 5 directory to your PATH. I recommend that rather than using the release-specific directory, you use /shared/local/java5, which is a link that will be updated to point to the latest version installed on the system.

MathWorks has announced the release of Service Pack 2 for Release 14 of MATLAB. I will be installing it as soon as I get hold of the media, but in the meantime, you can read about the changes in this release.

Please note that I will be installing the new release in parallel with the existing release. To use it, you will need to specify the complete path to the new version of MATLAB on the command line, or add the new directory to your PATH before the old directory.

Most students have probably left for spring break by now, but if you still happen to be around, you should be aware that a number of rooms are being used by the MCM and ICM contest judges.

The rooms include

• The Scientific-Computing Lab (Olin B159)
• The Math Clinic lab (Beckman B115)
• The Math Library (Olin B161)
• Beckman B134 (classroom near the soda machine)

Please let the judges work in peace, and avoid those rooms until Monday.

If you're in the habit of connecting to your dorm room machine as name.st, you should be aware that a recent change in the domain-name system means that you may not end up connected to the machine you meant to reach.

The DNS system allows partial domains to be completed, so typing dormbox.st on a math department system would cause the resolver to try dormbox.st, then dormbox.st.math.hmc.edu, and finally dormbox.st.hmc.edu.

The people responsible for the .st domain -- is a top-level country domain (TLD) meant for use by Saotome and Principe, an island nation in the Gulf of Guinea, near Africa -- have changed the behavior of their server so that any hostname ending in .st now resolves to a real site or to a site offering people the chance to buy that domain name. This change breaks the shortcut behavior you may have grown used to.

How Can You Know You're Affected?

If you try to ssh to your dorm machine and you see something like the following:

[user@mathhost]% ssh dormbox.st
The authenticity of host 'dormbox.st (195.178.186.40)' can't be established.
DSA key fingerprint is 48:fe:31:ba:16:9b:a2:ae:16:6d:f6:1f:cc:46:38:50.
Are you sure you want to continue connecting (yes/no)?

There are a couple of clues here. The first is that SSH is telling you that it doesn't know about the host you're trying to connect to. It does that if it's never connected to a particular machine before, or if the host key has changed (e.g., because the machine's operating system was reinstalled). The second is that the IP address -- 195.178.186.40 -- is not within the Claremont Colleges' IP address space, which starts with 134.173.

Notice that SSH gives you a ``key fingerprint'' to check the authenticity of the host. The SSH fingerprints of the machines in the mathematics department are available for you to check on our security information page, which will help you if you're connecting to them from another machine.

Alternative Shortcuts

Shell aliases offer a quick and easy way of defining a shortcut for reaching your dorm machine or other machines you connect to frequently. In addition to the hostname, you can also include other parameters that you would have to specify on the command line. For example, you might define an alias called home that actually runs the command ssh -X me@dormbox.st.hmc.edu, which can be especially handy if your username on the other machine is different than your username on the math cluster.

You can define such an alias with the following commands:

alias home 'ssh -X me@dormbox.st.hmc.edu (for csh/tcsh)
alias home='ssh -X me@dormbox.st.hmc.edu (for sh/bash/zsh)

You can define those aliases every time you log in by adding them to your ~/.tcshrc, ~/.cshrc, ~/.bashrc, or ~/.zshrc, depending on which shell you're running. And, of course, you can define as many as you like for any machines you routinely connect to.

I've added the TEXMF tree provided by Wolfram for use in compiling TeX documents exported from Mathematica to the system.

The files are located in /shared/local/share/Mathematica/texmf; to use them, modify your TEXMF environment variable by adding that directory. You will probably want something like

setenv TEXMF "$TEXMF, \!\!/shared/local/share/Mathematica/texmf" (*csh)
or
export TEXMF="$TEXMF, \!\!/shared/local/share/Mathematica/texmf" (Bourne/Korn variants)

which adds the files from the Mathematica TEXMF tree after the rest of the files in the standard TEXMF path.