Adding an existing SSH key to a newly installed Linux keyring is very easy but comes with a small step that needs to be performed before simply typing away ssh-add in the terminal.

  1. Copy both the private and public key to ~/.ssh/ directory.
    • Normally, if the SSH keys were not renamed, it would be something like id_rsa and
  2. Change the permission, apparently this is for the smooth transition without any problems.
    • Change the two public and private keys’ permission to 600.
    • For example - sudo chmod 600 ~/.ssh/id_rsa*.
  3. We simply add the key and verify it with password using ssh-add ~/.ssh/id_rsa.

It is necessary for the SSH agent to be running before you add the key but if it isn’t running, start it off with eval $(ssh-agent -s).

Generate Bourne shell commands on stdout. This is the default if SHELL does not look like it’s a csh style of shell. (Source: man ssh-agent)

That should add our existing SSH key to our keyring!