DACHS/Login

Access to DACHS is limited to IP addresses from the BelWü network. All home institutions of our current users are connected to BelWü, so if you are on your campus network (e.g. in your office or on the Campus WiFi) you should be able to connect to DACHS without restrictions. If you are outside one of the BelWü networks (e.g. at home), a VPN connection to the home institution or a connection to an SSH jump host at the home institution must be established first.

The login nodes of the DACHS cluster are the access points to the compute system, your $HOME directory and your workspaces. All users must log in through these nodes to submit jobs to the cluster.

Prerequisites for successful login:

You need to have

• completed the 3-step registration procedure.
• set a service password for DACHS.
• set up a second factor for the time-based one-time password (TOTP).

Login to the DACHS

Login to the DACHS is only possible with a Secure Shell (SSH) client for which you must know your username on the cluster and the hostname of the login nodes. For more general information on SSH clients, visit the SSH clients Guide.

Username

If you want to use DACHS, you need to add a prefix to your local username: prefix_username.

University	Prefix
HS Aalen	aa
HS Albstadt-Sigmaringen	as
HS Esslingen	es
HS Heilbronn	hn
HS Karlsruhe	hk
HTWG Konstanz	ht
HS Mannheim	mn
HS Offenburg	of
HS Reutlingen	hr
HfT-Stuttgart	hs
THU-Ulm	hu

For a full list of user names, you can check the bwIDM Hochschulen page.

Example:
If your local username for the University is vwxyz1234 and you are a user from the University of Esslingen this would combine to: es_vwxyz1234.

Hostnames

The system has two login nodes. The selection of the login node is done automatically. If you are logging in multiple times, different sessions might run on different login nodes.

Login to DACHS:

Hostname	Node type
dachs-login.hs-esslingen.de	login to one of the two login nodes

In general, you should use automatic selection to allow us to balance the load over the two login nodes. If you need to connect to specific login node, you can use the following hostnames:

Hostname	Node type
dachs-login1.hs-esslingen.de	DACHS first login node
dachs-login2.hs-esslingen.de	DACHS second login node

If you explicitly connect to dachs-login1 but end up on dachs-login2 (or the other way around), then of of them might not be available at the time and you're automatically redirected to the other one.

Host Keys

When you log in, you may receive the message The authenticity of host '<host address>' can't be established. along with the host key fingerprint. This is intended so you can verify the authenticity of the host you are connecting to. Before you continue you should verify, if this fingerprint matches one of the following:

Algorithm	Fingerprint (SHA256)
RSA	SHA256:kdvbATXbd/ggG33G7VEw+O+FpJPcZU6XDeFyWXvBkhc
ECDSA	SHA256:4Y/LvkPL9g9DZ8JrmTxXsMTIWyM/u/mEEmSB7S/2yyA
ED25519	SHA256:X9eRJepYD3da3BM1pgiWxnvRc/Pt5eBLUr18tDUsZjU

Login with SSH command (Linux, Mac, Windows)

Most Unix and Unix-like operating systems like Linux, Mac OS and *BSD come with a built-in SSH client provided by the OpenSSH project. More recent versions of Windows 10 and Windows 11 using the Windows Subsystem for Linux (WSL) also come with a built-in OpenSSH client.

For login use one of the following ssh commands:

ssh <username>@dachs-login.hs-esslingen.de
ssh -l <username> dachs-login.hs-esslingen.de

To run graphical applications, you can use the -X or -Y flag to ssh:

ssh -Y -l <username> dachs-login.hs-esslingen.de

For better performance, we recommend using VNC.

Login with graphical SSH client (Windows)

For Windows we suggest using MobaXterm for login and file transfer.

Start MobaXterm, fill in the following fields:

Remote name              : dachs-login.hs-esslingen.de
Specify user name        : <username>
Port                     : 22

After that click on 'ok'. Then a terminal will be opened and there you can enter your credentials.

Note: When using File transfer with MobaXterm version 23.6 the following configuration change has to be made: In the settings in the tab "SSH", change the option "SSH engine" from "<new>" to "<legacy>". Then restart MobaXterm

Login Example

To log in to DACHS, you must provide your service password. Proceed as follows:

1. Use SSH for a login node.
2. The system will ask for a one-time password Your OTP:. Please enter your OTP and confirm it with Enter/Return. If you do not have a second factor yet, please create one (see Registration/2FA).
3. The system will ask you for your service password Password:. Please enter it and confirm it with Enter/Return. If you do not have a service password yet or have forgotten it, please create one (see Registration/Password).
4. You will be greeted by the DACHS cluster, followed by a shell.

~ $ ssh -l es_vwxyz1234 dachs-login.hs-esslingen.de
(es_vwxyz1234@dachs-login.hs-esslingen.de) Your OTP: 123456
(es_vwxyz1234@dachs-login.hs-esslingen.de) Password: 
********************************************************************************
Last login: Thu Jul  7 18:09:43 2022 from dachs-login.hs-esslingen.de
********************************************************************************
[es_vwxyz1234@login1 ~]$ 

Troubleshooting

Nothing yet.

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 DACHS cluster 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.

We advise users to use interactive jobs for compute and memory intensive tasks like compiling.

Related Information

• If you want to reset your service password, consult the Password Guide.
• If you want to register a new token for the two factor authentication (2FA), consult the 2FA Guide.
• If you want to de-register, consult the De-registration Guide.
• If you need an SSH key for your workflow, read Registering SSH Keys with your Cluster.
• Configuring your shell: .bashrc Do's and Don'ts