Connecting to Triton

Videos

Videos of this topic may be available from one of our kickstart course playlists: 2024, 2023, 2022 Summer, 2022 February, 2021 Summer, 2021 February.

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.

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 provides graphical environments that are useful for interactive work.

  • SSH host name is triton.aalto.fi, use VPN if not on an Aalto network.

Method

Description

From where?

ssh from Aalto networks

Standard way of connecting via command line. Hostname is triton.aalto.fi. More SSH info.

>Linux/Mac/Win from command line: ssh USERNAME@triton.aalto.fi

>Windows: same, see Connecting via ssh for details options.

VPN and Aalto networks (which is VPN, most wired, internal servers, eduroam, aalto only if using an Aalto-managed laptop, but not aalto open). Simplest SSH option if you can use VPN.

ssh (from rest of Internet)

Use Aalto VPN and row above.

If needed: same as above, but must set up SSH key and then ssh -J USERNAME@kosh.aalto.fi USERNAME@triton.aalto.fi.

Whole Internet, if you first set up SSH key AND also use passwords (since 2023)

Virtual desktop

“Virtual desktop interface”, https://vdi.aalto.fi, from there you can ssh to Triton or access OOD. More info.

Whole Internet

Open OnDemand

https://ondemand.triton.aalto.fi, Web-based interface to the cluster. Also known as OOD. Includes shell access, GUI, data transfer, Jupyter and a number of GUI applications like Matlab etc. More info.

Whole internet

Jupyter

Since April 2024 Jupyter is part of Open OnDemand, see above. Use the “Jupyter” app to get same environment as before. More info.

See Open OnDemand above

VS Code / Codium desktop

With the “Remote-SSH” extension it can provide shell access and file transfer. See the VS Code page for some important usage warnings.

Same as SSH options above above.

Kickstart course preparation

Are you here for a SciComp KickStart course? You just need to make sure you have an account 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.

Schematic of cluster with current discussion points highlighted; see caption or rest of lesson.

We are working to get access to the login node. This is the gateway to all the rest of the cluster.

Getting an account

Triton uses Aalto accounts, but your account must be activated first.

The terminal

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 Using the cluster from a command line, will explain more about how to actually use it.

Image of terminal with two commands ran: ``whoami`` and ``hostname``

Image of a terminal - this is what you want after this page. You’ll see more about this means in Using the cluster from a command line. Don’t worry about what the commands mean, but you can probably figure out.

Connecting via ssh

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.

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.fi

If you are not in the Aalto networks, use the Aalto VPN.

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 which will ensure security.

See the advanced ssh information to learn how to log in without a password, automatically save your username and more. It really will save you time.

Aalto: 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.

Connecting via Open onDemand

See also

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. OOD is good for basic work, and an easier way to access a shell terminal. Read more from its guide.

To start a terminal, use the Triton shell access app.

Connecting via Jupyter

Link: https://ondemand.triton.aalto.fi → “Jupyter” app.

Triton used to have a JupyterHub installation, but now this has been replaced with the Jupyter app in Open OnDemand (see above). The configuration has been set to be similar to the old JupyterHub.

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.

Connecting via a Virtual Desktop

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.

VSCode

See also

VSCode on Triton

You can use a web-based VSCode through Open OnDemand. (update: not currently available in the new Triton since 2024 May) Desktop VSCode can also connect to Triton via SSH. Read more. Both of these can provide shell access and file transfer.

Warning: VS Code has some common issues with running calculations directly in it, see the VS Code page for more.

Exercises

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. Choose a method based on what is simple enough for your needs (we recommend SSH if you are comfortable with the command line, or Open OnDemand otherwise).

Type the command hostname to verify that you are on Triton. Run whoami to verify your username.

Connecting-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 comuter you are connected to? (You’ll learn more about these in Using the cluster from a command line, this is just a preview to fill some time.)

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 an expandable box above).

This $SHELL syntax is an environment variable and a pattern you will see in the future.

See also

What’s next?

The next tutorial is about using a command line.