How to update your SSH key

This article describes how to update the SSH key that you use to login to JASMIN machines. See SSH public key authentication for details of how ssh authentication works.

You may need to update your SSH key if:

  • You have forgotten the passphrase for your SSH key or have "lost" your key.
  • You have switched computers and are unable to copy your original ssh key to the new machine.
  • You believe that your SSH private key may have been compromised (for example, you left it in a place that other people could access).

Do not simply re-upload your old key. This is not secure. You must generate a new one, with a DIFFERENT passphrase, as detailed below.

If none of the above apply but you are experiencing problems logging in to JASMIN then we recommend that you read Login problems? then contact the Helpdesk, as updating your ssh key may not fix your problems.

Please note that only one SSH key can be stored in your JASMIN account. However, you can copy your SSH key pair to other computers (local to you) to allow you to login from them, provided that the computer satisfies our network requirements for security purposes (see Check network details).

How to update your key

1. Generate a new key pair

To update your SSH key you first need to generate a new key as described here: Generate an SSH key pair. This should be done on your local machine (e.g. Windows / Linux / Mac). You MUST protect your key with a strong passphrase. Use a new, different passphrase whenever you generate a new key.

2. Upload the PUBLIC part of the key to your JASMIN account

Once you have created your new key, you need to upload the public key to your JASMIN account. If you have followed the suggested key naming convention your public key should be in file ~/.ssh/ You can upload it to your JASMIN account via your JASMIN profile page. See Update a JASMIN account for more details of how to do this.

In order to upload your public key, you will need to know your JASMIN Accounts Portal password, and to look out for the verification code which will be sent to the email address associated with your JASMIN account.

3. Load your new key into your authentication agent on your local machine.

This article describes how to do this and use the key to log in from the various types of machine (Windows / Mac / Linux) which are in use.

Once you have uploaded your new public key you need to wait a few minutes before it will come into effect (allow up to 15 minutes).

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