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1 Login to the Clusters


Access to the clusters (bwUniCluster/bwForCluster) is restricted to IP addresses of universities/colleges from Baden-Württemberg (BelWü network). If you are outside the BelWü network (e.g. at home), you must first establish a VPN connection to your home university or a connection to an SSH jump host at your home university.

After completing the web registration, the HPC cluster is ready for your SSH based login. The following options for SSH connections are recommended:

  • Linux/MacOS: Use the ssh command (OpenSSH) in a terminal application.
  • Windows: Use the MobaXterm application. Alternatively, you can use virtual machines to run native Linux applications such as SSH. An easy way to use Linux on Windows is to install the "Windows Subsystem for Linux".

1.1 Hostnames and Login to bwUniCluster/bwForClusters

For specific instructions on logging in to the cluster and host names, see the following guides:

1.2 Username

All members of universities and colleges in Baden-Württemberg can use the bwHPC resources. Prefixes are used to ensure that the usernames assigned by the home organization are unique within the state. The username for the bwHPC clusters is the same as the one assigned by the university or college, but it is prefixed with two letters for the home institution. For users from KIT, however, there is an exception on the bwUniCluster (see table).

The following lists contain all prefixes currently in use.

University Prefix Username bwUniCluster Username bwForCluster
Universität Freiburg fr fr_<username>
Universität Heidelberg hd hd_<username>
Universität Hohenheim ho ho_<username>
Karlsruhe Institute of Technology (KIT) ka <username> ka_<username>
Universität Konstanz kn kn_<username>
Universität Mannheim ma ma_<username>
Universität Stuttgart st st_<username>
Universität Tübingen tu tu_<username>
Universität Ulm ul ul_<username>
HAW BW e.V. Prefix Username bwUniCluster/bwForCluster
Hochschule Aalen aa aa_<username>
Hochschule Albstadt-Sigmaringen as as_<username>
Hochschule Esslingen es es_<username>
Hochschule Heilbronn hn hn_<username>
Hochschule Karlsruhe hk hk_<username>
Hochschule Konstanz (HTWG) ht ht_<username>
Hochschule Mannheim mn mn_<username>
Hochschule Offenburg of of_<username>
Hochschule Reutlingen hr hr_<username>
Hochschule Rottenburg ro ro_<username>
Hochschule Stuttgart (HfT) hs hs_<username>
Hochschule Ulm hu hu_<username>

Alternatively, you can log in to the registration service and verify your username online. To do this, follow the next steps:

1. Select the cluster you want to know your username for:
bwUniCluster 2.0

2. Select your home organization from the list and click Proceed.

3. Enter your home-organisational user ID / username and your home-organisational password and click Login button.

4. You will be redirected back to the registration website.

5. Find the cluster entry and select Registry Info.

Check Registry Info.

6. Depending on the registration service, you will see one of the following entries. See Username for login or localUid for your username.

Username for login.
Username for login in localUid.

1.3 SSH Clients

Only the secure shell ssh is allowed for login. The following clients are recommended for using the bwHPC clusters.

For the <username>, see section "Username", for the <hostname>, see the cluster-specific instructions in section "Hostnames and Login to bwUniCluster/bwForClusters".

1.3.1 Command Line SSH

Most Unix and Unix-like operating systems like Linux, macOS and *BSD come with a built-in SSH client provided by the OpenSSH project. More recent versions of Windows 10 using the Windows Subsystem for Linux also come with a built-in OpenSSH client.

To use this client, simply open a command line terminal (the exact process differs on every operating system, but usually involves starting an application called Terminal or Command Prompt) and enter the following command to connect to a cluster:

$ ssh <username>@<hostname>

If you are on a Linux or Unix system running the X Window System (X11) and want to use a GUI-based application, you can use the -X option for the ssh command to set up X11 forwarding:

$ ssh -X <username>@<hostname>

Windows users requiring X11 forwarding for graphical applications should use MobaXterm instead.

1.3.2 MobaXterm

The bwHPC support team recommends to use MobaXterm instead of PuTTY or WinSCP on Windows. MobaXterm provides a built-in X11 server allowing to start GUI based software.

Select the session type ssh.

Start MobaXterm, fill in the following fields:

Remote name              : <hostname>
Specify user name        : <username>
Port                     : 22

Click 'OK'. A terminal will be opened and there you can enter your credentials.

1.3.3 FileZilla

Many GUI applications that support SFTP transfers on Linux don't work well with 2-factor authentication, e.g. Nautilus and Dolphin don't support it. A good alternative for Linux is FileZilla.

Start FileZilla, Select "File -> Site Manager..." from the main menu and set up a new connection with the following settings:

Protocol: SFTP - SSH File Transfer Protocol
Host: <hostname>
Logon Typ: Interactive
User: <username>

Then click on the "Connect" button.

Files can be transferred between the local system and the cluster by navigating to the respective folders in the split file view and then either dragging files and folders between the views or by clicking on a file/folder with the right mouse button and then selecting "Upload" or "Download" from the menu.

1.4 Examples

  • If you are a member of the University of Konstanz and your local username is ab1234, your username on any bwHPC cluster is kn_ab1234.
  • If your local username for the university is vwxyz1234 and you are a user from the University of Freiburg and you want to login to the bwUniCluster this would combine to the following SSH command:

Alternatively, you can also use -l for the user name:

 ssh -l fr_vwxyz1234
  • KIT users logging into bwUniCluster do not need to use a prefix, but if they are using a bwForCluster. If you are a KIT user and your username is pxd27239, your login names would be for the clusters:
    • bwUniCluster: pxd27239
    • bwForCluster: ka_pxd27239

1.4.1 Example login process for bwUniCluster 2.0

After the connection has been initiated, a successful login process will go through the following three steps:

1. The system asks for a One-Time Password. Generate one using the Software or Hardware Token registered on the bwIDM system (see Registration/2FA) and enter it after the Your OTP: prompt.

2. The systems asks for your service password. Enter it after the Password: prompt.

3. You are greeted by the bwUniCluster 2.0 banner followed by a shell.

The result should look like this:

Login example for bwUniCluster 2.0

1.5 Allowed Activities on Login Nodes


To guarantee usability for all the users of clusters you must not run your compute jobs on the login nodes. Compute jobs must be submitted to the queuing system. Any compute job running on the login nodes will be terminated without any notice. Any long-running compilation or any long-running pre- or post-processing of batch jobs must also be submitted to the queuing system.

The login nodes of the bwHPC clusters are the access point to the compute system, your $HOME directory and your Workspaces. These nodes are shared with all the users therefore, your activities on the login nodes are limited to primarily set up your batch jobs. Your activities may also be:

  • short compilation of your program code and
  • short pre- and post-processing of your batch jobs.