Accessing magsim

Magnet Group's computation server has the DNS name "magsim.ets.kth.se".

It can be accessed by SSH (Secure Shell, [v2], port 22) from any computer on the internet, using the username and password given for a magsim user account.

The SSH server also allows file-transfer (SCP -- secure copy) and X-forwarding (automated encrypted transmission of graphical-interace programs to the remote computer).


How to do it:

   from unixish-systems -- linux, *bsd, mac-osX, solaris, etc.

On most unix-type systems there will be a "ssh" and an "scp" command already installed -- try the manual pages for them with the command "man ssh".

So, you can use scp to move files, and ssh to get a command line (shell) on magsim, and therefore to run text-only programs such as "vi", "axiom", "octave", "matlab-7.0 -nodesktop" and literally a few thousand more.

So, if you are logging in from a unix-type system by ssh, then as long as you are running a graphical interface based on X11, and the ssh program at your end is configured to forward X, you just need to log in by ssh and start any graphical program, which will appear on your screen having been sent through an encrypted ssh channel.
If your ssh client is not configured for this, use the -X and possibly also the -Y options to use X forwarding. Consider also the -C (compression) option if you have a quite fast computer but a slow network.
If you can't forward X with ssh, then you need to ensure magsim knows where to send graphical windows and that your display is configured to allow magsim to connect to it ("xhost +magsim"). magsim should already have got the right DISPLAY setting (try "echo $DISPLAY" to see what it is: if ssh is not forwarding X you should find DISPLAY is your hostname with :0.0 after it).If DISPLAY is wrong, set it by "export DISPLAY=hostname:display.screen".

   other systems =- ms-windows, old macOS, ?

Further software may, as usual, be needed for use of the popular tasks of ssh and scp. For example, for microsoft-windows systems, the free programs "puTTY" and "WinSCP" may be used: putty does the job of remote login by ssh, WinSCP does the file-transfer job of scp (and WinSCP has a rather nice interface for file-transfer).

As these types of system also have no support for X, you will have to have some sort of extra X-server installed to allow graphical programs to be seen on your computer when running remotely. ETS seems to have "eXodus" available: have it installed if needed, then start the "Xserver" program to accept incoming X connections.
When you log in to magsim by ssh, you should find the DISPLAY environment variable is already set to your hostname with an appended ":0.0". If running exodus Xserver this should be the right setting. See the unixish-system section above for how to check and change DISPLAY.
Once the DISPLAY on magsim is correct and you have Xserver on your computer, graphical programs should come out on your screen when their programs are started.


Users of unix-type systems able to mount NFS (network file-system) on their computers may like their magsim home-directories to be exported to their own computers for convenience -- just ask. Due to the inherent insecurity of non-kerberised NFS, I'd only export the specific home directory to that one user's computer within ETS.


Users may wonder why telnet and ftp, or possibly samba (for ms-windows file-sharing) are not also provided.

For the telnet and ftp, the reasons are two: these are insecure protocols in any case, as they transmit unencrypted passwords (and data); and the more services I have open, the more things I have to consider upgrading and keeping track of for security.

For the samba server, the passwords can be encrypted, but the need to keep up to date is still there (not very crucial, if I restrict it to just the ETS network) and samba has ben far less secure in its history than ssh! Also, as ms systems uses different password encryption from unix systems, the samba passwords have to be set up separately, which is messy. But if it seems desired and is agreed by those responible for buying the computer and setting up the network I can certainly add this service.