Computer Accesss

Class Accounts

You will have class accounts for the Linux machines located in Ungar 426 (the computer science computer laboratory). This is the room where the class is held. There are about 25 machines in the room, with two servers which run the show: lee and davis. Davis is the file server (so all you files are on Davis, although you won't notice this, they will seem to be on the machine in front of you). Lee is an additional computer you can use for remote logins, to work in the lab when you are away from the room.

To login remotely, use ssh to Only ssh is permitted. Using ssh you can have a graphical, remote desktop using X windows. While X (X11 more precisely) is the only way to go for Linux uses, so no additional explanations are needed, Windows and OSX users might not understand how this works.

In the Unix world, the graphical interface (and the machine that owns the interface) and the computer and the computer you are working on are very separate things. The graphical interface as supplied by a machine called an X server. Think of the X server as an old fashioned terminal, except it does graphics instead of just lines of text. The X client is the machine you are logged into. So lee can be an X client, if you are running an X server, and using ssh you can make this connection. After which, it is exactly like working in the lab (except that the network can be slow, because the entire desktop is being sent back and forth).

Some people might think of this as PC Anywhere, or Citrix software. It is sort of like that, except with these products, the desktop, and all the graphics is still on the remote machine, and all that is being sent back and forth are bitmaps of what should be on the screen. With X, all the graphics is done locally on the X server, which is the machine sitting in front of you, and all the remote machine, the client, does is ask for graphical services.

I don't do remote desktops often. The bandwidth isn't there. But to do it is easy. Use ssh with the -X option, to establish an X connection back to your machine. You will need X installed on your machine, you will need that your machine be an X-server. For Linux, X is what you have; for OSX you just need to install X from the installation CD (although now it might be pre-installed); for Windows, they've been stubborn about this, you will probably have to buy an X server to run on your machine.

Web servers

A class account with username user has a folder public_html. Putting things in this folder they will appear on the web at location We wil also work on getting accounts with PHP privleges, which isn't a given, because of security concerns. We will turn on this options for students in the course.