Log in to Puhti

‼️ To begin make sure you have a user account at CSC that is a member of a project which has access to the Puhti service and perhaps Allas. Note that there’s a small delay before one can login to Puhti after creating a new project and adding services.

‼️ In order to log in with SSH from the command-line, you must have also set up SSH keys and uploaded your public key to MyCSC. See the previous tutorial.

Puhti web interface

💬 Connecting via the Puhti web interface is an easy way to access the Puhti supercomputer.

Open a web browser and go to https://www.puhti.csc.fi
Login with your CSC account (or Haka/Virtu)
You have now connected to Puhti!

💭 The Puhti web interface landing page looks like this:

Puhti web interface

💡 From the pinned apps and top menus you can, for example, access your files and open some applications or a command-line interface.

Connecting with SSH from the command-line

💬 The basic Command-Line Interface (CLI) in Unix-based systems is the Terminal.

💡 Different operating systems have slightly different CLIs and SSH clients, i.e. programs that you can use to connect to the supercomputers.

Connecting from Linux and macOS

💬 Laptops and workstations running Linux or macOS typically have SSH pre-installed.

Find the Terminal on your computer:

terminal-icon

Open a terminal and type (replace cscusername with your CSC username):
```
ssh cscusername@puhti.csc.fi
```
- Note! If you have saved your SSH key with a non-default name or in a non-default location, please specify the path to your key using the -i option:
```
ssh cscusername@puhti.csc.fi -i /path/to/private/key
```
You may be prompted to type your SSH key passphrase.

💡 To avoid having to type your passphrase every time you connect to a CSC supercomputer, the ssh-agent utility can hold your keys in memory. Using ssh-agent is not necessary, but makes using SSH keys very convenient!
- On Linux systems, ssh-agent is typically configured and run automatically at login and requires no additional actions on your part.
- On macOS systems, you should add the following lines to the ~/.ssh/config file:
```
Host *
    UseKeychain no
    AddKeysToAgent yes
```
Scroll down to In Puhti.

Connecting from Windows

💬 On Windows you have different options:

You can use the Puhti web interface to connect with your browser (easiest, see above).
You can download and install MobaXterm.
You can download PuTTY.
You can use the Windows PowerShell. See Docs CSC.

‼️ The following steps assume you use MobaXterm. More examples can be found in Docs CSC.

Launch MobaXterm from the applications list (opens from the Windows logo), or search for it in the bottom bar search box.
Click Session in the top-left corner and select SSH.
In the Basic SSH settings section, write puhti.csc.fi in the Remote host field.
Tick the Specify username box and enter your CSC username. The Port number can be left as 22 (default).
In the Advanced SSH settings section, tick the Use private key box and add the path to the SSH private key you generated in the previous tutorial.
Click OK. If it is the first time you are connecting to Puhti, click Accept.
You are asked to enter your SSH key passphrase.

💡 To avoid having to type your passphrase every time you connect, you may enable the MobAgent authentication agent in the program settings, Settings > SSH > SSH agents. Tick the Use internal SSH agent “MobAgent” box and select the key(s) you want to load.
You’ve now connected to Puhti!

💡 The next time you want to login to Puhti, just select it from the User session menu on the left!

💡 Note, you may also login with MobaXterm using the plain ssh command similar to Linux and macOS (see image below).

In Puhti

If you’re connecting to Puhti (or a specific Puhti login node) for the first time, SSH will ask you if you trust the authenticity of the host:

The authenticity of host 'puhti-login14.csc.fi' can't be established.
ECDSA key fingerprint is SHA256:kk0Tar9opQ+6Gq0GWJdWVVvFEMeI6kW1DW1VOYveT5c.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

The first time you connect, you need to accept, but the key should not change for the next login.
Pay attention to whether you logged in to puhti-login11, puhti-login12, puhti-login14 or puhti-login15.

Once you’ve logged in you’ll see a greeting starting something like this:

┌─ Welcome ───────────────────────────────────────────────────────────────────┐
│         CSC - Tieteen tietotekniikan keskus - IT Center for Science         │
│            ____        __    __  _                                          │
│           / __ \__  __/ /_  / /_(_)   - -  -   -                            │
│          / /_/ / / / / __ \/ __/ /   - -  -   -                             │
│         / ____/ /_/ / / / / /_/ /   - -  -   -                              │
│        /_/    \__,_/_/ /_/\__/_/   - -  -   -                               │
│                                                                             │
│      Puhti.csc.fi - Atos BullSequana X400 - 682 CPU nodes - 80 GPU nodes    │
├─ Contact ───────────────────────────────────────────────────────────────────┤
│ Servicedesk : 09-457 2821, servicedesk@csc.fi   Switchboard : 09-457 2001   │
├─ User Guide ────────────────────────────────────────────────────────────────┤
│ https://docs.csc.fi                                                         │
├─ Manage my account ─────────────────────────────────────────────────────────┤
│ https://my.csc.fi/                                                          │
├─ Software ──────────────────────────────────────────────────────────────────┤
...
└─────────────────────────────────────────────────────────────────────────────┘
[cscusername@puhti-login14 ~]$

Now, you’re ready to go!
Let’s do our first small task in Puhti: let’s check our projects and that we have a one with access to Allas service!
```
csc-projects
module load allas
allas-conf
```
1. The first command csc-projects lists your projects.
2. The second command module load allas loads the Allas tools in your use.
3. The third command allas-conf sets up the connection to Allas: it will ask for your CSC password, and then you need to select which project you want to use (by typing the number of the project, for example 2).
  - If you don’t see a project here, please return to CSC account and project tutorial and ensure that you have a project with access to Allas service. Please note that it can take up to an hour after accepting the terms of use before the service is in use.

Remote graphics

💬 Remote graphics may not work by default. Try the Puhti web interface for running graphical applications.

💬 Another option is to enable X11-tunneling as follows.

On Linux and macOS

Add X11-tunneling to your SSH connection by adding -X or -Y to your ssh command like this (replace cscusername with your CSC username):
```
ssh -X cscusername@puhti.csc.fi
```
Note that on Mac you need to have an X server running, for example XQuartz. You also need to set in your .bashrc:
```
export DISPLAY=:0
```

On Windows

MobaXterm will actually tunnel the connection by default!
PuTTY requires that an X server is installed and running. One of the options is Xming.
In PuTTY, X11 forwarding is enabled in the connection settings: Connection > SSH > X11: Enable X11 forwarding.

☝🏻 For intensive remote graphics we recommend using the Puhti web interface.

More information

💭 Docs CSC: Connecting