Hardware and software infrastructure

General

For the practical assignments, you are supposed to use a dedicated machine running some server software. The machine is tricolor.students.cs.uu.nl.

To be able to work on this machine and thus work on the assignments you need a CS-login. If you don't have one yet (because you enrolled as a non-Computer Science student, for instance), please get one now from our Helpdesk.

Tricolor

The tricolor server lies within the students network. You can login to this machine using your usual student login name/password combination. If you cannot, this is because you can not login to the student network at all. Visit the Balie in BBL to obtain an account on our network. However, only rarely will you ever need to really go to the tricolor machine: most things can be handled via a special directory on your student account.

If you make a directory called public_html in your home directory (normally mounted as the H: drive), it will be automatically visible on the tricolor. You can view the website by browsing to http://tricolor.students.cs.uu.nl/~studentname. Do not forget to set the access rights of the public_html directory (executable for everybody, readable and writable for yourself) and make sure the files in that directory are readable for everybody. One thing you very likely must take care of, is to also make your home directory executable for everybody. Otherwise, the server can not access your public_html directory. More information in the next paragraph.

A drawback of the public_html set-up is that everyone can cd to your home directory. However, they can not list that directory (unless you give read rights as well, which you should not). If they know what files your directory contains, they can access these files without you knowing. This is why you might want to explictly deny other people all rights to your account, except those rights which are really needed by the webserver to access the website. A way to do this is to execute the following from a Unix terminal (do not do this directly from Windows).

chmod 701 ~ ; chmod -R 705 ~/public_html

What it does, is to retract all access by people in your group and 'other's to all files and directories on your account to nothing, except for the necessary execute access to your home directory and the public_html directory and of course the necessary read and execute rights for anything within the public_html directory. Generally, this will work fine. Note however though that if you create new files on your account, that you may have to set the read rights of others off, because most programs turn these on by default when you create a new file. It is possible to avoid this by setting a umask correctly. If you want that, look up the details yourself.

You can obtain a Unix terminal by doing ssh to a machine such as shell.students.cs.uu.nl (if you have the proper things set up).

Learn more about SSH and other services at Computer Science right here.

Some help with PHP and PostgreSQL for the assignments

Remote access

We do not really care where you really work to make your assignments, but one of the prerequisites is that they should (eventually) work on the tricolor. It is not possible to directly access the tricolor from outside. To gain remote access to tricolor, you should use SSH in combination with our proxy service.

Technical documentation on SSH in combination with our proxy service is available, but note that the documentation can only be accessed from a machine within the cs.uu.nl domain.

Setting up remote access may be a bit of a hassle, but it will be useful to you throughout your studies. ;-)

Note that if you are busy with this anyway, you might as well setup VPN too to get remote access to other services of the Department as well.

Subversion

If you're tired of exchanging new versions of certain files of your assignment with your co-worker by e-mail, you might consider using Subversion. See the subversion page from our Helpdesk for more information.


lennart@cs.uu.nl