SSH gateways

Accessing the servers directly

Access and file tranfers are done through the SSH protocol (ssh, scp, rsync, sftp, or any graphical user interface built upon SSH: MobaXTerm, Filezilla, Cyberduck, etc.) in a very standard way with your CISM login and password.

Important

When you will connect for the first time, the program you are using most probably will ask you to verify the fingerprint of the public SSH key of the server you are trying to connect to. Ideally, you should contact the admins to verify that key. If you do not, please make sure that you are connected to a trusted network before answering ‘Yes’.

Using the command line

You will need a terminal emulator and an SSH client.

To start a terminal:

  • Linux: hit Ctrl + Alt + T
  • Mac: search for “term” in Spotlight
  • Windows: hit Ctrl + Shift + P

Once the terminal is open, you can type in commands. To use the SSH client to connect to a machine, run the following command:

ssh -X <my_cism_login>@<machine_name>.cism.ucl.ac.be

Make sure to replace the part <my_cism_login> with your actual login and <machine_name> with the name of the computer you want to connect to. The -X option allows using software with a graphical user interface (GUI). You can ignore it if all you need is a command line interface (CLI).

Note that on MacOS, you will need to install XQuartz for this to work. On Windows, you will need XMing.

When you login, you will be asked for your password. You should then give the password you chose when you created your account. You can spare the need for typing the password at every login by using SSH keys. See Creating and using SSH keys.

You should furthermore configure your SSH client (in the .ssh/config file) to avoid having to type your login and the full name of the servers each time. See the documentation here for instance.

Copying files

The usual way is to use the commands scp, sftp, and/or rsync. You can always use any graphical user interface you like as long as it uses scp or sftp to make the transfers. For instance, you can run the following in a terminal:

scp -r <source_dir> <my_cism_login>@<machine_name>.cism.ucl.ac.be:<target_dir>

to transfer <source_dir> on your laptop to <target_dir> on the machine, and

scp -r  <my_cism_login>@<machine_name>.cism.ucl.ac.be:<source_dir> <target_dir>

to copy a directory back. See the scp manpage for more examples or type ‘’man scp’’ or ‘’man rsync’’ to get information about those commands.

Windows alternative: MobaXTerm

On Windows, the easiest way is to install (or simply download) MobaXterm. You can request it from the university IT support team, or install it by yourself, without admin privileges.

  1. Download and start MobaXterm

Go to the MobaXterm website and download the free version. Make sure to select the prtable edition from the download page. Create a MobaXterm folder on your Windows user Documents one and uncompress inside it the contents of the downloaded zip file. We chose to create the MobaXterm folder on that particular location and we will refer to that on this guide. You can, of course, select some other location of your preference if you wish. The steps showed here has been done with version 20.2 of MobaXterm. Some behaviors may change between version.

Double click the MobaXterm_Personal_XX.X.exe executable file inside the
Documents\MobaXterm folder. You should see the MobaXterm main window like this one:
mobaxterm main
  1. Click on the Session icon session icon on the top left corner.
  2. The Session settings configuration panel will open, select the SSH session type ssh icon and you should see a window like this:
ssh settings window
  1. In the Remote host field, introduce the full name of the server (interactive server or mass storage server) that you want to connect to. Tick the Specify username box and introduce your CISM username.
  2. Click the “OK” button and enter your CISM password when requested.

The first time, MobaXTerm will ask whether or not to remember the password. Alternatively, you can setup SSH keys that allow for more security and easier jumps from one server to another.

You are now connected and you can run commands.

  1. Copying files to and from the cluster

After you succeeded to setup the shortcut for connecting to a server you will see on the left sidebar on the Sftp tab a file browser on the server you are connected to.

You can simply drag and drop files from your computer to that panel and they will be copied to the cluster. The same is valid for retrieving files from the cluster to your computer.

If you right click on that panel, you will see different options to interact with the browser (see the figure below). Remember always to press the Refresh current folder button after you copied something or a new file or folder is created on the cluster.

session desktop shortcut

Note that you also have the right-click options directly available through the icons on the toolbar at the top of the panel.

For more information, please refer to the MobaXterm documentation.

GUI file manager

FileZilla is a two-pane graphical file transfer software available for Linux, Mac and Windows.

After you have downloaded and installed it following the instructions on the FileZilla website, you can connect to a computer by writing the full name of the server in the Host: text box, your CISM login in the Username: text box, and your CISM password in the Password: box. Put 22 in the Port: box and then click “Quickconnect”. FileZilla will ask you whether or not it should remmember the password and then it will connect.

../../_images/FileZilla-1.png

Working from home

The servers hosted by the CISM are located on a sub-network that is not reachable directly from outside the network of the university. That does not prevent you from accessing them from anywhere, provided you use an SSH gateway.

The SSH gateways allow you to access resources that are available only inside the university network eventhough you are home or abroad. With the gateway, you can connect to the CECI clusters, to Manneback, to the interactive machines, or to the storage machines that are normally only accessible when you are connected to the university network (wired or wifi ).

There are two gateways that you can use, depending on the account you have.

Note

You do not need to be abroad or home to use and test the connection to the gateway. Make sure it all works through the gateway when you are in your office before attempting to connect from home.

  • CISM account: use gwcism.cism.ucl.ac.be
  • CÉCI account: use gwceci.cism.ucl.ac.be

Please note the following restrictions in the use of the gateways:

  • the CÉCI gateway can only be used as a jump host, you will not be able to SSH to it directly.
  • the CISM gateway can only reach the CISM clusters, mass storage and interactive machines.

To know how to configure the CÉCI gateway, please refer to the CÉCI documentation:

The remaining of this section will focus on gwcism and its use with the interactive servers and mass storage servers.

Using the command line

A direct way of specifying a gateway is to use the -J option of ssh:

ssh -X -J <my_cism_login>@gwcism.cism.ucl.ac.be <my_cism_login>@<machine_name>.cism.ucl.ac.be

Make sure to replace the parts in <my_cism_login> with your actual login and <machine_name> with the name of the computer you want to connect to.

As that can become cumbersome to type, the best is to configure the SSH client to remember that information for us. That is done in the ~/.ssh/config file.

If that file does not exist yet, you can create it. Then, populate it with the following content

Host gwcism
  Hostname gwcism.cism.ucl.ac.be
  User <my_cism_login>

Host <machine_name>
  Hostname <machine_name>.cism.ucl.ac.be
  User <my_cism_login>
  ProxyJump gwcism

Make sure to replace all the items in angle brackets <>. You can copy the section Host <machine_name> section for all the servers you want to connect to:

Host gwcism
  Hostname gwcism.cism.ucl.ac.be
  User <my_cism_login>

Host cesam
  Hostname cesam.cism.ucl.ac.be
  User <my_cism_login>
  ProxyJump gwcism

Host storage
  Hostname storage.cism.ucl.ac.be
  User <my_cism_login>
  ProxyJump gwcism

When that is configured, you can then connect to the server using only its shortname, like this for cesam for instance:

ssh cesam

Windows alternative: MobaXTerm

First create a session as before to connect to the server you want. But before you click on OK, click the Advanced SSH settings tab and choose the Network settings tab.

Then click on “SSH gateway (jump host)”

ssh gateway config

Enter gwcism.cism.ucl.ac.be in the Gateway host text box, your CISM login in the Username text box, and 22 in the Port text box.

ssh gateway config

Press the OK button and you should be prompted for your password. MobaXTerm will ask you if it should remeber it.

If everything was properly configured, you should now be connected.

GUI file manager

Unfortunately, FileZilla cannot directly use an SSH gateway. It can use a SOCK proxy or an SSH tunnel though, that is less easy to configure. If you want to use FileZilla from home or abroad, the best option is to use the unversity VPN or MobaXterm.

ALSOreplicus

This directory was created for you when you registered. It is given as a simple means to organize a replication-based backup strategy. This strategy consists in duplicating all your data on distinct servers in distinct rooms so as to minimize losses due to hazard.

Every file that you copy in this directory is synchronized every hour on another server in another room. Note that therefore, the space you use in that directory is charged twice!

Note that because it is used twice on distinct servers ; data in ALSOreplicus are copied every hour onto another server to serve as a simple backup procedure.