Connecting to DAIC

SSH access

If you have a valid DAIC account (see Access and accounts), you can access DAIC resources using an SSH client. SSH (Secure SHell) is a protocol that allows you to connect to a remote computer via a secure network connection. SSH supports remote command-line login and remote command execution. SCP (Secure CoPy) and SFTP (Secure File Transfer Protocol) are file transfer protocols based on SSH (see wikipedia's ssh page ).

Access from the TU Delft Network

To connect to DAIC within TU Delft network (ie, via eduram or wired connection), open a command-line interface (prompt, or terminal, see Wikipedia's CLI page ), and run the following command:

$ ssh <YourNetID>@login.daic.tudelft.nl # Or
$ ssh login.daic.tudelft.nl             # If your username matches your NetID 

<YourNetID> is your TU Delft NetID. If the username on your machine you are connecting from matches your NetID, you can omit the square brackets and their contents, [<YourNetID>@].

This will log you in into DAIC’s login1.daic.tudelft.nl node for now. Note that this setup might change in the future as the system undergoes migration, potentially reducing the number of login nodes..

The authenticity of host 'login.daic.tudelft.nl (131.180.183.244)' can't be established.
ED25519 key fingerprint is SHA256:MURg8IQL8oG5o2KsUwx1nXXgCJmDwHbttCJ9ljC9bFM.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'login.daic.tudelft.nl' (ED25519) to the list of known hosts.

• Fingerprints of login nodes:
• login1
• login2
• login3

SHA256:MURg8IQL8oG5o2KsUwx1nXXgCJmDwHbttCJ9ljC9bFM

SHA256:MURg8IQL8oG5o2KsUwx1nXXgCJmDwHbttCJ9ljC9bFM

SHA256:O3AjQQjCfcrwJQ4Ix4dyGaUoYiIv/U+isMT5+sfeA5Q

Once identity confirmed, enter your password when prompted (nothing will be printed as you type your password):

The HPC cluster is restricted to authorized users only.
YourNetID@login.daic.tudelft.nl's password:

Next, a welcome message will be shown:

Last login: Mon Jul 24 18:36:23 2023 from tud262823.ws.tudelft.net
 #########################################################################
 #                                                                       #
 # Welcome to login1, login server of the HPC cluster.                   #
 #                                                                       #
 # By using this cluster you agree to the terms and conditions.          #
 #                                                                       #
 # For information about using the HPC cluster, see:                     #
 # https://login.hpc.tudelft.nl/                                         #
 #                                                                       #
 # The bulk, group and project shares are available under /tudelft.net/, #
 # your windows home share is available under /winhome/$USER/.           #
 #                                                                       #
 #########################################################################
 18:40:16 up 51 days,  6:53,  9 users,  load average: 0,82, 0,36, 0,53

And, now you can now verify your environment with basic commands:

YourNetID@login1:~$ hostname  # show the current hostname
login1.hpc.tudelft.nl
YourNetID@login1:~$ echo $HOME  # show the path to your home directory
/home/nfs/YourNetID
YourNetID@login1:~$ pwd  # show current path
/home/nfs/YourNetID
YourNetID@login1:~$ exit  # exit current connection
logout
Connection to login.daic.tudelft.nl closed.

In this example, the user, YourNetID, is logged in via the login node login1.hpc.tudelft.nl as can be seen from the hostname output. The user has landed in the $HOME directory, as can be seen by printing its value, and checked by the pwd command. Finally, the exit command is used to exit the cluster.

Access from outside university network

Direct access to DAIC from outside the university network is blocked by a firewall. To access DAIC, you have two options:

1. Using the Linux Bastion Server

To connect to DAIC via the Linux Bastion Server:

1. SSH into the bastion server. The bastion server acts as a gateway to the DAIC cluster.

   • If you are an employee or guest, use linux-bastion.tudelft.nl.
   • If you are a student (BSc or MSc) use student-linux.tudelft.nl.

   ssh <YourNetID>@linux-bastion.tudelft.nl #OR
   ssh linux-bastion.tudelft.nl             # If your username matches your NetID
   

   As with DAIC login nodes, the first time you attempt to login to the bastion, you will be asked to confirm the server’s identity. Upon confirmation and entering your password, a welcome screen will be shown:

   The authenticity of host 'linux-bastion.tudelft.nl (131.180.123.195)' can't be established.
   ED25519 key fingerprint is SHA256:VJUFsQkIebODETsXwczkInnRrpdYYqAZDbsoKP1we+A.
   This key is not known by any other names                                                                     
   Are you sure you want to continue connecting (yes/no/[fingerprint])? yes 
   Warning: Permanently added 'linux-bastion.tudelft.nl' (ED25519) to the list of known hosts.
   YourNetID@linux-bastion.tudelft.nl's password:                                                                
                   ____  ____ _____                                         
    ___ _ ____   _|___ \|___ \___  |                                                                            
   / __| '__\ \ / / __) | __) | / /                                                                             
   \__ \ |   \ V / / __/ / __/ / /                                                                              
   |___/_|    \_/ |_____|_____/_/                                                                               
   
   YourNetID@srv227:~$
   

2. Once on the bastion server, SSH into DAIC as shown in SSH access.

   YourNetID@srv227:~$ ssh login.daic.tudelft.nl # Or any other login node
   

$ ssh -J [<YourNetID>@]linux-bastion.tudelft.nl [<YourNetID>@]login.daic.tudelft.nl

2. Using a VPN

You can also use TU Delft’s EduVPN or OpenVPN (See TU Delft’s Access via VPN recommendations ) to access DAIC directly. Once connected to the VPN, you can ssh to DAIC directly, as in Access from the TU Delft Network.

Simplifying SSH with Configuration Files

To simplify SSH connections, you can store configurations in a file in your local machine. The SSH configuration file can be created (or found, if already exists) in ~/.ssh/config on Linux/Mac systems, or in C:\Users\<YourUserName>\.ssh on Windows.

For example, on a Linux system, you can have the following lines in the configuration file:

Host daic
  HostName login.daic.tudelft.nl # Or any other login node
  User <YourNetID>
Host bastion
  Hostname linux-bastion.tudelft.nl # If employee/guest. Else, use: student-linux.tudelft.nl instead
  User <YourNetID>
  PreferredAuthentications password

where:

• The Host keyword starts the SSH configuration block and specifies the name (or pattern of names, like daic in this example) to which the configuration entries will apply.
• The HostName is the actual hostname to log into. Numeric IP addresses are also permitted (both on the command line and in HostName specifications).
• The User is the login username. This is especially important when the username differs between your machine and the remote server/cluster.

You can then connect to DAIC from inside TU Delft network by just typing the following command:

$ ssh daic

Or, if outside the university network, you can connect via the bastion server:

$ ssh bastion

And, similarly, you can create/modify the configuration file on the bastion server (in ~/ssh/config) by adding a Host configuration block for DAIC as above, to simplify the connection to DAIC from there.

ssh proxy jump feature

To connect directly from your machine to a DAIC login node (when outside the university network), use the ssh Jump Host option to jump the bastion server as follows:

$ ssh -J YourNetID@linux-bastion.tudelft.nl YourNetID@login.daic.tudelft.nl # use `student-linux.tudelft.nl` instead if you are a student

For convenience, you can also edit your ssh configuration file, ~/.ssh/config, on your local computer as follows:

Host daic
  Hostname login.daic.tudelft.nl
  User <YourNetID>
  ProxyJump linux-bastion.tudelft.nl # For employees and guests. If you are a student, use: student-linux.tudelft.nl instead

Where:

*ProxyJump: Specifies the jump server, bastion in this case.

You can then simply use: ssh daic to login.

Efficient SSH Connections with SSH Multiplexing

SSH multiplexing allows you to reuse an existing connection for multiple SSH sessions, reducing the time spent entering your password for every new connection. After the first connection is established, subsequent connections will be much faster since the existing control connection is reused.

To enable SSH multiplexing, add the following lines to your SSH configuration file. Assuming a Linux/Mac system, you can add the following lines to ~/.ssh/config:

Host *
  ControlMaster auto
  ControlPath /tmp/ssh-%r@%h:%p

where:

• The ControlPath specifies where to store the “control socket” for the multiplexed connections. %r refers to the remote login name, %h refers to the target host name, and %p refers to the destination port. This ensures that SSH separates control sockets for different connections.
• The ControlMaster setting activates multiplexing. With the auto setting, SSH will use an existing master connection if available or create a new one when necessary. This configuration helps streamline SSH connections and reduces the need to enter your password for each new session.

This setup will speed up connections after the first one and reduce the need to repeatedly enter your password for each new SSH session.