Computer Lab Client Systems

TL;DR

Some more background and details

This page describes how you can login to the machines of the computer lab from elsewhere, so not directly on the console, but keep in mind that:

You can log in on the other computer lab machine(s) and work as if you were on the console itself. You can do so not only terminal/character/command line based (basic SSH use) but also with GUI applications where all windows you create appear on your own screen. The latter will only work though, if the machine from which you are working has a local X-service - more details are given here.

Take care not to log in on a machine on which others are running intensive applications, because you do not only interfere with these applications, but you yourself are also bothered by them because the system might become overloaded. You can see the load of the machines on the same page where the available machines are listed (see below). There are of course safeguards that protect a machine from becoming overloaded - you can read more about them in the history of niceness.

You must use SSH to connect to the systems, but it also depends from where you want to connect from:

  • From (most) KU Leuven networks (including kotnet) you can connect directly to the computer lab machines - no special setup needed, just use SSH to connect - more specifically, you do not need to set up or use SSH keys as described below if you connect in this way.
  • Otherwise (e.g. from home) you must first connect to a machine within KU Leuven (the jumphost) and from there the computer lab machines are accessible. How to connect to the jumphost, depends of course on which one you want to use - below you can find instructions to use the departmental student jumphost st.cs.kuleuven.be, but the main principle of using a jumphost should be the same for all of them.

Regardless of how you login to the client systems, once logged in you will have direct access to command line utilities (yes, even matlab!). If you want to use GUI applications, you must do so using at least some specific configuration and possibly need to install extra software on your local machine - see here for more detailed instructions.

=> Either Direct SSH Connection

You know whether a direct SSH connection is possible if you can SSH directly into one of the client machines or if you can access the web page with the name of the machines - just try it when in doubt (and remember: the client systems are all in the .student.cs.kuleuven.be domain).

  • https://mysql.student.cs.kuleuven.be/
  • on Microsoft Windows, Apple MacOS and Linux: ssh r1234567@name.student.cs.kuleuven.be
    • in the past on Microsoft Windows: use MobaXterm or PuTTY
    • these still work, but the command line ssh command is probably easier because it works in exactly the same way as on MacOS and Linux

If this succeeds, you are all set and you do not need to worry about the rest of this text about the jumphost or SSH key setup - just go ahead and start using the system you just connected to, with or without GUI/X11 forwarding.

If you know none of the names of the client systems and if you cannot access the web page with their names, you must use a jumphost (e.g. st.cs.kuleuven.be) as described below.

=> Or Connect via a SSH Jumphost

You can most probably use any machine within KU Leuven networks where you can connect to using SSH, but in case you do not know one, the department provides such a jumphost for students: st.cs.kuleuven.be.

2 important remarks about st.cs.kuleuven.be:

  • it is only configured to be used with KU Leuven student accounts (of the form [mrs]1234567) - members of the department should use a departmental ssh server with their departmental account.

  • moreover the accounts must be configured for use in the computer labs

Special notes for members of the department:

  • using a departmental ssh server as jumphost is exactly the same as described below: just replace st.cs.kuleuven.be with the name of the ssh server you want to use - and remember that you most probably need to login on the jumphost using your departmental login account but on the computer lab system itself using your u-number:
    • ssh -X -J login@ssh.cs.kuleuven.be u1234576@name.student.cs.kuleuven.be
  • you can use exactly the same procedure as described below to log in to a departmental system and use it from home or elsewhere (including GUI/X11 forwarding) - there just isn't a nice web page with all the names of the available systems, you'll have to remember the name(s) of the system(s) you want to work on. Depending on where you want to connect from, you can use a direct SSH connection or you must use one of the departmental public SSH servers as jumphost:
    • ssh -X -J login@ssh.cs.kuleuven.be login@name.cs.kuleuven.be

Access the web page with the names of the machines via the jumphost:

  • First set up a tunnel to the web service:
    • on Microsoft Windows, Apple MacOS and Linux:
      • ssh -L 10443:mysql.student.cs.kuleuven.be:443 r1234567@st.cs.kuleuven.be
    • in the past on Microsoft Windows met PuTTY and/or MobaXterm:
      (click to open and see the details - these still work, but the above command line ssh command is probably easier because it works in exactly the same way as on MacOS and Linux)
      • on Microsoft Windows using PuTTY, the equivalent of the -L option is a tunnel configuration (in Connection -> SSH -> Tunnels):
        • L10443 mysql.student.cs.kuleuven.be:443
        • connect to st.cs.kuleuven.be with r1234567 as Username
      • on Microsoft Windows using MobaXterm: see this tunnel documentation with the following data:
        • Local port = 10443
        • MyJumpHost = st.cs.kuleuven.be with r1234567 as Username and port 22
        • MyRemoteServer = mysql.student.cs.kuleuven.be with port 443
  • Then, on the same machine as you execute the above ssh, visit:

Login to a client system of the student computer lab via a jumphost:

  • on Microsoft Windows, Apple MacOS and Linux use the -J and/or Proxycommand options:
    • ssh -J r1234567@st.cs.kuleuven.be r1234567@name.student.cs.kuleuven.be
    • if -J option is not available:
      ssh -o ProxyCommand="ssh -W %h:%p r1234567@st.cs.kuleuven.be" r1234567@name.student.cs.kuleuven.be
    • if you want to forward GUI/X11 as well, also use the -X option
  • on Microsoft Windows using PuTTY: see this jumphost documentation
  • on Microsoft Windows using MobaXterm: see this jumphost documentation

Advanced use: access your computer lab home directory from anywhere:

  • on Apple MacOS and Linux: (long lines are wrapped for readability)
    • sshfs -o ssh_command='ssh -J r1234567@st.cs.kuleuven.be' \
      r1234567@name.student.cs.kuleuven.be:/home/r1234567 /path/to/local/mount/directory
    • if -J option is not available:
      sshfs -o ssh_command='ssh -o ProxyCommand="ssh -W %h:%p r1234567@st.cs.kuleuven.be"' \
      r1234567@name.student.cs.kuleuven.be:/home/r1234567 /path/to/local/mount/directory
  • on Microsoft Windows:
    • follow MobaXterm instructions above for easy SFTP access (including using a jumphost)