Getting access to the Tufts HPC

You will get an email from aff-account@tufts.edu asking you to set up your Tufts account. Following the instructions in this email, you should

1. Reset your Tufts password
2. Follow instructions to set up Duo Security
3. Set up your VPN connection with Cisco AnyConnect

Once all of these steps have been completed, you can connect to the HPC through the terminal with your new tufts username: ssh TUFTS_USERNAME@login.pax.tufts.edu. You must be connected to the Tufts VPN for this to work.

You will get a message saying:

The authenticity of host 'login.pax.tufts.edu (XX.XXX.XXX.XX)' can't be established.
ED25519 key fingerprint is SHA256:{{someLongFingerprint}}.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

• Enter ‘yes’ when you are asked if you want to keep connecting. This will trust the server from now on and add login.pax.tufts.edu to the list of known hosts in ~/.ssh/known_hosts/. You won't get this prompt again.

Setting up passwordless HPC connection

Set up a SSH key-based authentication so you don't need to enter your Tufts password each time you connect to the Tufts HPC

1. Generate an SSH key pair:

• ssh-keygen -t ed25519 -C tufts_email@tufts.edu
• Press "enter" to save the key at /Users/local_username/.ssh/id_ed25519
• This creates:
  • ~/.ssh/id_ed25519 (private key — keep safe)
    • ~/.ssh/id_ed25519.pub (public key — to be shared with servers)
      ⚠️ Warning

      Anyone with access to your private key can sign in as you with all of your privileges. Do not share with anyone, or upload the key to anywhere that others have access to.

2. Copy your public key to the HPC login node
   • ssh-copy-id tufts_username@login.pax.tufts.edu
   • After entering your password again, this will append your public key to the file ~/.ssh/authorized_keys on the HPC server

You can test if this works by entering ssh tufts_username@login.pax.tufts.edu

Setting up ~/.ssh/config

To simplify things even further, you can set up a ~/.ssh/config file so that you can use access the Tufts HPC by simply typing ssh tufts-hpc.

1. If you don't already have a ~/.ssh/config file, create one by typing nano ~/.ssh/config. Then, add the following information into the file.

Host tufts-hpc
	    HostName login.pax.tufts.edu
	    User tufts_username
	    IdentityFile ~/.ssh/id_ed25519
	    Port 22

2. To make sure that no one can access this file except for you, run chmod 600 ~/.ssh/config
3. Once the file has been saved, you can type ssh tufts-hpc
4. To exit the cluster, type exit.

Helpful directories on the cluster

Once you have access to the Tufts HPC, you can access your personal directory within the Bonham Lab folder at /cluster/tufts/bonhamlab. This is a good place to store data/results for personal projects.

• The shared bin (/cluster/tufts/bonhamlab/shared/) also contains helpful directories with conda environments, apptainer containers, bioinformatics tools (bin) and biobakery databases ( databases)

Troubleshooting:

• Some other lab members received a Tufts username and email, but an HPC account was not created for them. If your newly created Tufts password does not allow you to connect to the HPC, this could be something to check.