Connecting to HPC

Connecting with SSH (Windows)

Windows

Download and install MobaXterm.

Generating a pair of keys

Run MobaXterm, click on Start local terminal, and execute the following command:

ssh-keygen -t rsa -f my_hpc_key

This command will prompt you for a passphrase twice and create two files: my_hpc_key (the private key) and my_hpc_key.pub (the public key). Keep both files in a protected local folder such as C:\Users\XXX\Documents\MobaXterm\home\ (replace XXX with your user name).

What to do with the keys

Security rule: Keep my_hpc_key on your local computer. Never email it, upload it to cloud storage, commit it to Git, or copy it to the cluster or another remote host. The cluster administrator authorizes the matching public key (my_hpc_key.pub) in your account, usually in ~/.ssh/authorized_keys.

When connecting from another trusted personal computer, create a separate local key pair for that device and ask the administrator to add that device's public key. Use the private key only in the SSH client running on the computer you control.

Connecting with SSH

If you want to run graphical applications from outside the university’s network, or if you prefer a graphical desktop, refer to the Connecting with NX section.

From inside the university’s network

In the MobaXterm window:

• Click on Session (upper left corner), then SSH.
• Fill the Remote Host field with hpc.example.edu (replace with your institution's HPC address).
• Tick the Specify username box and enter the login name provided by the administrator.
• In the Advanced SSH settings tab, tick the Use private key box and set its location to your private key file.
• Click OK.
• A new session should appear in the left panel; double-click it to connect.

From outside the university’s network

Once connected via VPN, refer to the instructions in the "From inside the university’s network" section above to establish your SSH connection.

File transfer

Once connected with MobaXterm, you can easily transfer files by dragging and dropping them in the left panel.

Connecting with SSH (Linux / Mac)

Connecting with SSH

If you want to run graphical applications from outside the university’s network, or if you prefer a graphical desktop over the console, refer to the Connecting with NX section.

From inside the university’s network

Add the following lines to your ~/.ssh/config file. Replace your_username with the login name provided by the administrator:

Host hpc_alias
        Hostname hpc.example.edu
        User your_username
        IdentityFile ~/.ssh/my_hpc_key

Explanation: * Host hpc_alias: This line defines an alias (hpc_alias). The options that follow this line will only be applied when ssh recognizes this alias. * Hostname hpc.example.edu: Specifies the address of the remote host. * User your_username: Defines the username to use for the connection. * IdentityFile ~/.ssh/my_hpc_key: Tells ssh to use the specified private key for authentication.

With this configuration, you can connect using:

ssh hpc_alias

Important: The following command will not work as expected because the IdentityFile option will not be used:

ssh your_username@hpc.example.edu

The alias hpc_alias can be changed to any name you prefer.

From outside the university’s network

To connect from outside the university’s network, you must first request VPN access from the network administrator. Once granted, follow the instructions provided by the administrator.

Alternatively, if you prefer not to use a graphical VPN client (like gnome or network-manager), you can:

• Install openvpn.
• Download the configuration files from the provided address.
• Extract the archive and navigate into the directory.

• With root privileges, run:

  bash openvpn vpn-univ-TCP-443.ovpn

Once connected via VPN, refer to the instructions in the "From inside the university’s network" section above to establish your SSH connection.

Connecting with NX

Connecting with NX

Install x2goclient. It may be available as a package for your Linux/Mac distribution, or you can download it (also for Windows) from the provided link.

To set up a new session:

• Click on Session, then New session….
• Optionally, change the Session name.
• Enter hpc.example.edu in the Host field.
• Fill in the Login field with your username.
• Set the location of your private key in the Use RSA/DSA key for ssh connection field.
• In the Session type box, choose either:
  • XFCE for a graphical desktop environment.
  • Single application, then Terminal from the right drop-down menu for a terminal session.
• Click Ok. The session should appear in the right panel. Click on it to connect.

Important: If you are outside the university’s network, you must first connect to the VPN. Refer to the From outside the university’s network section above for VPN instructions.