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Change or set the passphrase of an SSH key

cautionSSHalle

Caution: This command changes the system. Understand what it does before you run it.

Adjust the values, the command updates live
user@server
ssh-keygen -p -f ~/.ssh/id_ed25519_server

Asks for the old passphrase and twice for the new one, then saves the private key encrypted with the new passphrase. The public key stays the same, so nothing needs to be changed on the servers. An empty new passphrase removes the protection.

Note: If you have forgotten the old passphrase, there is no way around generating a new key pair.

Also searched as

  • how to change ssh key passphrase
  • add passphrase to existing ssh key
  • remove ssh key passphrase

Related one-liners

All in SSH

Derive the public key from a private SSH key

$ssh-keygen -y -f ~/.ssh/id_ed25519_server
harmlessSSH

Generate an Ed25519 SSH key pair

$ssh-keygen -t ed25519 -a 100 -C "admin@example.com" -f ~/.ssh/id_ed25519_server
harmlessSSH

Copy your public SSH key to a server

$ssh-copy-id -i ~/.ssh/id_ed25519_server.pub -p 22 webuser@server.example.com
cautionSSH

Remove an outdated host from known_hosts

$ssh-keygen -R server.example.com
cautionSSH

Show the fingerprint of an SSH key

$ssh-keygen -lf /etc/ssh/ssh_host_ed25519_key.pub
harmlessSSH

Start ssh-agent and load a key for a limited time

$eval "$(ssh-agent -s)" && ssh-add -t 4h ~/.ssh/id_ed25519_server
harmlessSSH

Read first, then run.

The commands on myline.de act directly on servers, files and databases. A wrong path or placeholder can delete data irreversibly or make a server unreachable.

  • All commands are provided without warranty and are not tested on every system.
  • Understand what a command does before running it, and check every placeholder.
  • Make a backup first and, if possible, try it on a test system.
  • You run commands at your own risk. Liability for damages is excluded to the extent permitted by law.