ssh-keygen (command)

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ssh-keygen[1] is an OpenSSH software command used to generate, manage, and convert authentication keys. It support at least four different key types RSA, DSA, ECDSA and ed25519.



Generate a key par[edit]

[-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]

Two files will be generated, one your private key and a second file containing second key (.pub extension)
  • ssh-keygen -t ed25519 -f ~/.ssh/your_new_ed25519_key
  • ssh-keygen -t ed25519 -f ~/.ssh/your_new_ed25519_key -C "your_coment_or_email_address

  • Generate FIDO key:
  • ssh-keygen -t ecdsa-sk -f ~/.ssh/id_ecdsa_sk
  • Generating public/private ecdsa-sk key pair.

Generate with PEM format:


ssh-keygen -e -m PEM -f private_key_in_ed25519_format
do_convert_to_pem: unsupported key type ED25519
  • ssh-keygen -l -f ~/.ssh/
  • -l Show fingerprint of specified public key file.
  • is not a public key file.

Legacy format[edit]


  • ssh-keygen -l -E md5 -f ~/.ssh/

See also: puttygen -O fingerprint

  • ssh-keygen -vF host (-v flag added in OpenSSH 8.1[3])


  • OpenSSH 7.8, released in August 2018 Incompatible changes: ssh-keygen write OpenSSH format private keys by default instead of using OpenSSL's PEM format.


ssh-keygen -t ed25519
ssh-keygen -R SERVER_NAME -R Removes all keys belonging to hostname from a known_hosts file
ssh -oStrictHostKeyChecking=no SERVER_NAME Temporarily turning off host key checking
Both solutions have security implications.
  • Change or encrypt private key withouth changing the key: [4]

ssh-keygen -f ~/.ssh/id_rsa -p

ssh-keygen -y -f ~/.ssh/id_rsa > ~./.ssh/
  • Generate a key par with old PEM format using:
ssh-keygen -m PEM
  • Changing the private key's passphrase without changing the key[5]

ssh-keygen -f ~/.ssh/id_rsa -p

-p change the passphrase of a private key file
ssh-keygen -lf
2048 SHA256:u6IaFqRcwp0QX0nPBa/HHB2k/g73tH+YkoaE0riGRAT NAME@XX (RSA)
ssh-keygen -lf your_key
your_key is not a key file.

Related terms[edit]

See also[edit]

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