2. Connecting to the cluster

Below you can find a few basic steps, to get you setup and ready to connect to EOS.

2.1. Terminal

If you are on a UNIX system (i.e. either Linux or Mac OS), a terminal will already be present natively in your operating system.

If you are on Windows, then we recommend you install MobaXTerm which is a very good UNIX emulator, and includes already useful things like an X server and a package management system to help you use languages like python or perl.

2.2. Generate your ssh key

First of all you should verify if you already have an SSH key in your system, which you might have generated earlier yourself or by using another software. To do this, open your terminal and type ls -la ~/.ssh

If you already have one or more keys, you will see a list, like in the example below

[user@machine ~]$ ls -la ~/.ssh
total 4
drwx------  2 user group    3 Feb  9 15:42 .
drwxr-x--- 17 user group   25 Feb 20 12:32 ..
-rw-------  1 user group 1152 Feb  9 15:42 authorized_keys
-rw-------  1 user group  227 Jan 14 10:01 id_ecdsa
-rw-------  1 user group  178 Jan 14 10:01 id_ecdsa.pub

If you do not have a key already, and the command above does not list any .pub file, then you should generate one.

In order to generate a key, you should type

ssh-keygen -t ed25519 -C "your_email@example.com"

In some systems, you might have to choose a different encription and use:

ssh-keygen -t rsa -C "your_email@example.com"

When you’re prompted to “Enter a file in which to save the key,” press Enter. This accepts the default file location. Similarly, if you just enter when a passphrase is requested, it will generate the key without one.

Now you should print at screen the public key that you just generated, in order to use it in the next step.

cat ~/.ssh/id_rsa.pub

or use id_ecdsa.pub depending on the encryption you have used.

Warning

You always want to copy the .pub file because this is the public key you can share. The other key is a private one, which you should never share.

2.3. Request an account

Once you have generated or identified your public key, you will use that when requesting an account, following this link.

This procedure might be subject to changes.

2.4. Connect to the cluster

When you receive confirmation, that your account has been activated, you can then connect to the cluster by opening a terminal and using:

ssh user@eos.unipv.it

If you need to display any graphics, you can use instead

ssh -X user@eos.unipv.it

And a session on the terminal will be opened, within the login node of the cluster.

Note

In order for a graphical window to be functional on MacOS an X server needs to be installed, because the OS does not have a native one like in Linux. We recommend XQuartz.

If you are connecting for the fist time, and if you have received a first-time password, the login node will ask you to change it at your first login.

Warning

If you are connecting to the cluster after a system recovery, it is possible that the identification key of the login node has changed. Your computer will compare it with the version it stored in the file:

/user/.ssh/known_hosts

which keeps track of the trusted connections you make, and will return an error because of the mismatch.

All you have to do, is delete existing line referring to eos.unipv.it. A new one will be written next time you connect, with the updated identification key.