BwForCluster User Access/2FA Tokens

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Revision as of 14:02, 30 October 2020 by C Mosch (talk | contribs) (Registering a new Software or Hardware Token)
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Currently this description is only valid for bwForCluster JUSTUS 2.

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

1 How 2FA works

A six-digit auto-generated time-dependent One-Time Passwords (TOTP) is used. These TOTPs are generated either by a special hardware device (hardware token) or by an application running on a smartphone or computer (software token).

The token has to be synchronized with a central server (a shared secret is exchanged) before it can be used for authentication and then generates an endless stream of six-digit values (TOTP 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.

Typically a new TOTP value is generated every 30 seconds. When the current TOTP value has once been used successfully for a login, it is depleted and one has to wait up to 30 seconds for the next TOTP value.

1.1 Hardware tokens

Generally hardware tokens are available for users from the Karlsruhe Institute of Technology (KIT). Every KIT member automatically gets a hardware token when joining the KIT.

Hardware Token used at KIT

1.2 Software tokens

Software tokens (typically an app on your smartphone) are available for all bwHPC users.

It is very important that the device that generates the One-Time Passwords and the device which is used to log into the bwForCluster 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

Open source apps for Android are available via f-droid store: andOTP Authenticator, Aegis Authenticator and Yubico Authenticator.

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 tokens are generally managed via the My Tokens menu entry on the central bwIDM registration server. Here you can register, activate, deactivate and delete tokens.

Usually a TOTP token that has been connected to your account is valid for all clusters on the registration server. Thus you can use the same TOTP token for bwUniCluster 2.0 and JUSTUS 2.

KIT users can also re-use their existing hardware and software tokens for the HPC systems.

In addition to your regular hardware/software token we recommend to register at least one backup TAN list, i.e. for emergencies when access to your regular hardware/software token has been lost. You should print and store the backup TAN list at a safe location.

2.1 Registering a new Software or Hardware Token

1. First you need to login to the bwIDM registration server (if you are not logged in already).

2. After login please select entry My Tokens in the User menu.

3. If you have not setup any tokens yet you can directly proceed with step 4 below (since token management is accessible directly for users without tokens). Otherwise (a token is already connected to your account) you need to log into the token management by entering a TOTP and clicking on Check.

4. 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. If you want to generate a backup TAN list, click on Create new TAN list and proceed with step 9.


5. A new windows 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 bwIDM 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

6. 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.

7. Once the QR code has been loaded into your software token app there should be a new entry called bwIDM.

8. 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 bwIDM browser window to prove that the connection has worked and then click on Check.

9. 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

In case of a backup TAN list, click on Show TANs, then Print the TAN list and store the printout at a safe location:


10. 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. In such a case please follow instructions of the next section.

11. If you are in the process to register for a bwForCluster, then you can proceed with the next step on the registration server.

3 Recovery when access to all tokens has been lost

To gain access again after you have lost access to all your tokens including the backup TAN list, please contact the JUSTUS 2 support via bwSupport Portal (NOT email !!!) and ask for reset of all your TOTP tokens. This process will take its time.

4 Deactivating a Token

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

5 Deleting a Token

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