Instructions for instructors

The DTU databar

The summer school exercises will be running in the DTU Databar, not on Niflheim. You can log in with your DTU username and password. Like Niflheim, it has a login node and a number of compute node, but unlike Niflheim it also has interactive compute nodes where the students and you can run e.g. your Jupyter notebooks.

Logging in

ssh -X login.gbar.dtu.dk

Then proceed from the login node to an interactive compute node with the command:

linuxsh -X

Creating an SSH key pair (while at DTU!)

When you are on the DTU network (or use a VPN) logging in requires authentication with either a password or a cryptographic key. But once we are off-campus, it requires both. It is much easier to set up while still on DTU.

Creating a key pair on Mac or Linux

First check if you already have a public key on your laptop. In a terminal, type:

cd
ls -lh .ssh

Look for files named id_rsa and id_rsa.pub. If they are not there, create them with the command:

ssh-keygen -b 4096 -t rsa

When prompted for a file name, just keep the default. When asked for a password, you can choose one if you feel paranoid / security minded, or leave it blank to avoid having to type a password when you use the key.

Once the file have been created, log in to the databar and type the following commands:

cd
mkdir -p .ssh
nano .ssh/authorized_keys

In that file, paste the content of the file id_rsa.pub from your laptop. Press Ctrl-X to exit the “nano” editor, and choose Yes to save the file.

Not open a new window and try logging in to the databar. If you are at DTU, you should no longer be prompted for a password.

Creating a key pair on Windows

Open MobaXterm. On the Tools menu, choose MobaKeyGen

Leave parameters as default (RSA, 2048 bits). Click Generate, and move the mouse to generate randomness. When the key is ready, click “Save private key”. Choose a name that makes sense. You can set a passphrase if you feel paranoid / security-minded.

Keep the MobaKeyGen window open (if you close it, you can load the private key again). Log in to the DTU databar. On the databar, run the commands:

cd
mkdir -p .ssh
nano .ssh/authorized_keys

Now copy the private key from the top field of the MobaKeyGen window (with Ctrl-C), and then paste it into the nano editor by right-clicking on the window. Once the key is pasted, press ENTER so the line ends with a line break. Then exit the “nano” editor by pressing Ctrl-X, say Yes to save the file.

Now log out of the databar and close the MobaKeyGen window.

Click on the Settings button (one of the last ones on the MobaXTerm toolbar). On the configuration window that opens you select the SSH tab. The last box is labeled “SSH agents”, select “Use internal SSH agent MobAgent”.

Click the Plus sign next to the box labeled “Load the following keys at MobAgent startup” and then select the file you just saved with your private SSH key. Then press OK; MobaXterm will then need to restart.

Setting up the Virtual Environment etc

To prepare your account, run the script (you only need to do this once):

bash ~jasc/setup2026

(This is the same script the students will be running to set up their account).

This will create a folder CAMD2026, a virtual environment in CAMD2026/venv, and a MyQueue configuration.

A line is added to your .bashrc to automatically activate the virtual environment. Remove it and activate manually if it causes trouble.