The traditional way of interacting with a cluster is via the command line in a shell in a terminal, and Secure Shell (ssh) is the most common way of doing that. To learn more command line basics, see our shell crash course </scicomp/shell>.
Abstract
- When connecting to a cluster, our goal is to get a command-line terminal that provides a base for the rest of our work.
- The standard way of connecting is via ssh, but Open OnDemand and Jupyter provide graphical environments that are useful for interactive work.
- SSH host name is
triton.aalto.fi, use VPN if not on an Aalto network.
Kickstart course preparation
Are you here for a SciComp KickStart course? You just need to make sure you have an account <../accounts> and then be able to get to a terminal (as seen in the picture below) by any of the means here, and you don't need to worry about anything else. Everything else, we do tomorrow.
Local differences
The way you connect will be different in every site, but you should be able to get a terminal somehow.
console
Triton uses Aalto accounts, but your account must be
activated first <../accounts>.
This is what you want by the end of this page: the command line terminal. Take the first option that works, or the one that's comfortable to you. However, it's good to get ssh working someday, since it is very useful. Later, in cluster-shell, will explain more about how to actually use it.
cluster-shell. Don't worry about what the commands mean, but you can probably figure out.
ssh is one of the most fundamental programs of remote connections: by using it well, you can really control almost anything from from anywhere. It is not only used for connecting to the cluster, but also for data transfer. It's worth making yourself comfortable with its use.
Linux
All Linux distributions come with an ssh client, so you don't need to do anything. To use graphical applications, use the standard -X option, nothing extra needed.:
$ ssh triton.aalto.fi
## OR, if your username is different:
$ ssh USERNAME@triton.aalto.fiIf you are not in the Aalto networks, use the Aalto VPN.
MacOS
ssh is installed by default, usage is the same as in the Linux tab after starting the Terminal application. To run graphical applications, you need to install an X server (XQuartz).
Windows with WSL
Install the Windows Subsystem for Linux and then use the Linux instructions. This will give you a top-level interface to scientific work on your computer and is highly recommended.
This may not work if you do not have proper admin rights on your computer (e.g. if it is university managed). Ask your IT support well in advance for help!
Windows with PowerShell
If you can't use WSL, you can also use PowerShell. Start the "Windows PowerShell" program. Then, follow the Linux instructions. If you want to set up ssh keys there are a few differences but overall it is the same procedure.
Windows with PuTTY
If you can't use WSL, then you can install a separate terminal application.
PuTTY is the standard SSH client. If you want to run graphical programs, you need an X server on Windows: see this link for some hints. (Side note: putty dot org is an advertisement site trying to get you to install something else.)
You should configure PuTTY with the hostname, username, and save the settings so that you can connect quickly.
If you are not on an Aalto network, there are extra steps. We recommend you use the Aalto VPN rather than any other workarounds. (Aalto networks are VPN, Eduroam, wired workstations, internal servers, and aalto network only if using an Aalto-managed computer.)
When connecting, you can verify the ssh key fingerprints
<../usage/ssh-fingerprints> which will ensure security.
See the advanced ssh information </scicomp/ssh> to learn how to log in without a password, automatically save your username and more. It really will save you time.
SSH from outside the Aalto networks
If you are from outside the Aalto networks, use the ProxyJump option (-J) in modern OpenSSH to connect directly to Triton without VPN. This is more work than VPN, since you have to set up SSH keys AND use a password anyway:
$ ssh -J kosh.aalto.fi triton.aalto.fi
## OR, if your username is different:
$ ssh -J USERNAME@kosh.aalto.fi USERNAME@triton.aalto.fi
## If you do not have the -J option:
$ ssh kosh.aalto.fi
$ ssh triton.aalto.fiSSH configuration file
This is described under the advanced ssh information
</scicomp/ssh>, but here is a quick summary:
If you use OpenSSH (Linux/MacOS/WSL or Windows Powershell instructions above), the .ssh/config file (on windows the .ssh folder is commonly under C:\Users\YourUsername) is valuable to set up to make connecting more seamless, with this you can run ssh triton_via_kosh instead of using the -J option - and this same triton_via_kosh will work with what you learn on the remotedata page!:
Host triton
User USERNAME
Hostname triton.aalto.fi
Host triton_via_kosh
User USERNAME
Hostname triton
ProxyJump USERNAME@kosh.aalto.fiAalto: Change your shell to bash
Only needed if you shell isn't already bash. If echo $SHELL reports /bin/bash, then you are already using bash.
The thing you are interacting with when you type is the shell -the layer around the operating system. bash is the most common shell, but the Aalto default shell used to be zsh (which is more powerful in some ways, but harder to teach with). Depending on when you joined Aalto, your default might already be bash. We recommend that you check and change your shell to bash.
You can determine if your shell is bash by running echo $SHELL. Does it say /bin/bash?
If not, ssh to kosh.aalto.fi and run chsh -s /bin/bash. It may take 15 minutes to update, and you will need to log in again.
../usage/ood
OOD (Open onDemand) is a web-based user interface to Triton, including shell access, and data transfer, and a number of other applications that utilize graphical user interfaces. Read more from its guide
<../usage/ood>. The Triton shell access app will get you the terminal that you need for basic work and the rest of these tutorials.
It is only available from Aalto networks and VPN. Go to https://ood.triton.aalto.fi and login with your Aalto account.
../apps/jupyter
Jupyter is a web-based way of doing computing. But what some people forget is that it has a full-featured terminal and console included.
Go to https://jupyter.triton.aalto.fi (not .cs.aalto.fi) and log in. Select "Slurm 5 day, 2G" and start.
To start a terminal, click File→New→Terminal - this is the shell you need. If you need to edit text files, you can also do that through JupyterLab (note: change to the right directory before creating a new file!).
Warning: the JupyterHub shell runs on a compute node, not a login node. Some software is missing so some things don't work. Try ssh triton.aalto.fi from the Jupyter shell to connect to the login node. To learn more about Jupyterlab, you need to read up elsewhere, there are plenty of tutorials.
If you go to https://vdi.aalto.fi, you can access a cloud-based Aalto Linux workstation. HTML access works from everywhere, or download the "VMWare Horizon Client" for a better connection. Start a Ubuntu desktop (you get Aalto Ubuntu). From there, you have to use the normal Linux ssh instructions to connect to Triton (via the Terminal application) using the instructions you see above: ssh triton.aalto.fi.
You can use a web-based VSCode through Open OnDemand. Desktop VSCode can also connect to Triton via SSH. Read more <../apps/vscode>
If you are in the kickstart course, Connecting-1 is required for the rest of the course.
Connecting-1: Connect to Triton
Connect to Triton, and get a terminal by one of the options above. Type the command hostname to verify that you are on Triton. Run whoami to verify your username.
$ hostname
login3.triton.aalto.fi
$ whoami
darstr1Connecting-2: (optional) Test a few command line programs
Check the uptime and load of the login node: uptime and htop (q to quit - if htop is not available, then top works almost as well). What else can you learn about the node? (You'll learn more about these in cluster-shell, this is just a preview to fill some time.)
You should see something like this. From this example output we can tell that the node was last rebooted 18 days ago, and the load average seems pretty high (1 = "about one processor in use". There are 24 processors in 2023. Load of 1-5 would be normal). Someone is running things directly on the login node, which is not good:
$ uptime
17:32:25 up 18 days, 3:20, 128 users, load average: 29.46, 32.78, 34.28More info:
$ lscpu
(long output not listed here)
$ uname -a # tells a bit about operating system info
Linux login3.triton.aalto.fi 3.10.0-1160.83.1.el7.x86_64 #1 SMP Wed Jan 25 16:41:43 UTC 2023 x86_64 x86_64 x86_64 GNU/LinuxWe'll see more in cluster-shell.
Connecting-3: (optional, Aalto only) Check your default shell
Check what your default shell is: run echo $SHELL. If it doesn't say /bin/bash, go ahead and change your shell to bash if it's not yet (see the expandable box above).
This $SHELL syntax is an environment variable and a pattern you will see in the future.
$ echo $SHELL
/bin/bash(advanced but recommended) Connecting-4: SSH configuration
If you use Linux/MacOS/WSL, start setting up a .ssh/config file as shown above and in /scicomp/ssh. You probably won't have time to finish this, but you can resume later. Customize it to suit your case.
The "solution" is listed in the linked documents.
/scicomp/ssh
The next tutorial is about using the terminal <cluster-shell>.