BwForCluster MLS&WISO Production 2FA tokens

From bwHPC Wiki
Jump to: navigation, search

Since June 18, 2021 a 2-factor authentication mechanism (2FA) is being enforced for logins to bwForCluster MLS&WISO to improve security. In addition to the service password a second value, the second factor, has to be entered on every login.

1 How 2FA works

For bwForCluster MLS&WISO we use six-digit, auto-generated, time-dependent One-Time Passwords (TOTP). These passwords are generated by a normal application running on a common device (a Software Token).

The Token has to be synchronized with a central server before it can be used for authentication and then generates an endless stream of six-digit values which can only be used once and are only valid during a very short interval of time. This makes it much harder for potential attackers to access the HPC system, even if they know the regular service password.


It is very important that the device that generates the One-Time Passwords and the device which is used to log into bwForCluster MLS&WISO are not the same. Otherwise an attacker who gains access to your system can steal both the service password and the secret key of the Software Token application, which allows them to generate One-Time Passwords and log into the HPC system without your knowledge.

The most common solution is to use a mobile device (e.g. your smartphone or tablet) as a Software Token by installing one of the following apps:

  • GNOME Authenticator for Linux

These are only suggestions. You can use any application compatible with the TOTP standard.

An example of the FreeOTP app on Android, displaying generated One-Time Passwords for various services

2 Token Management

bwForCluster MLS&WISO Tokens are generally managed via the My Tokens menu entry on bwServices. Here you can register, activate, deactivate and delete Tokens.

BwServices my tokens.png

2.1 Registering a new Software or Hardware Token

1. Registering a new Token starts with a click on New smartphone token. If you happen to own a USB Hardware Token device made by the manufacturer Yubikey, you can click on New Yubikey Token instead.

BwUniCluster 2.0 2fa register new empty.png

2. A new window opens. Click on Start to generate a new QR code. This may take a while.

NOTE: The QR code contains a key which has to remain secret. Only use the QR code to link your Software Token app with bwServices in the next step. Do not save the QR code, print it out or share it with someone else. You can always generate more codes later.

BwUniCluster 2.0 2fa register new qr.png

3. Start the Software Token app on your separate device and scan the QR code. The exact process is a little bit different in every app, but is usually started by pressing on a Button with a Plus (+) sign or an icon of a QR code.

4. Once the QR code has been loaded into your Software Token app there should be a new entry called bwServices. Generate an One-Time-Password by pressing on this entry or selecting the appropriate button/menu item. You will receive a six-digit code. Enter this code into the field labeled "Current code:" in your bwServices browser window to prove that the connection has worked and then click on Check.

5. If everything worked as expected, you will be returned to the My Tokens screen and there will be a new entry for your Software Token:

BwUniCluster 2.0 2fa register new success.png

6. Repeat the process to register additional tokens. Please register at least a Backup TAN list in addition to the hardware/software token you plan to use regularly. If you only register a single token and happen to lose access to it, e.g. because you lose your device, uninstall the software token application or data gets deleted/corrupted, you will neither be able to log into the cluster system nor register a new token. The support channels are able to deactivate your lost token, but this process will take its time. Please do not use the Backup TANs for regular Cluster login, because you have only a limited number of TANs!

3 Deactivating a Token

Click on the Disable button next to the Token entry on the My Tokens screen.

4 Deleting a Token

After a Token has been disabled a new button labeled Delete will appear. Click on it to delete the Token.