How to change/update key pair for ec2 instance – AWS

Instruction from AWS EC2 support:

  1. Log into your AWS account
  2. go to your EC2 Console
  3. Under NETWORK & SECURITY, click on Key Pair Click on Create Key Pair
  4. Give your new key pair a name, save the .pem file. The name of the key pair will be used to connect to your instance
  5. Create SSH connection to your instance and keep it open
  6. in PuttyGen (https://www.puttygen.com/), click "Load" to load your .pem file
  7. Keep the SSH-2 RSA radio button checked. Click on "Save private key" You'll get pop-up window warning, click "Yes”
  8. click on "Save public key" as well, so to generate the public key. This is the public key that we're going to copy across to your current instance
  9. Save the public key with the new key pair name and with the extension .pub
  10. Open the public key content in a notepad
  11. copy the content below "Comment: "imported-openssh-key" and before "---- END SSH2 PUBLIC KEY ----
    Note - you need to copy the content as one line - delete all new lines
  12. on your connected instance, open your authorized_keys file using the tool vi. Run the following command: vi .ssh/authorized_keys you should see the original public key in the file also
  13. move your cursor on the file to the end of your first public key content :type "i" for insert
  14. on the new line, type "ssh-rsa" and add a space before you paste the content of the public key , space, and the name of the .pem file (without the .pem) Note - you should get a line with the same format as the previous line
  15. press the Esc key, and then type :wq!

this will save the updated authorized_keys file

now try open a new SSH session to your instance using your new key pai

When you've confirmed you're able to SSH into the instance using the new key pair, u can vi .ssh/authorized_key and delete the old key.

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