~/.ssh/authorized keys

mkdir -p ~/.ssh && touch ~/.ssh/authorized_keys && chmod 700 ~/.ssh && chmod 600 ~/.ssh/authorized_keys

mkdir -p .ssh && touch .ssh/authorized_keys && chmod 700 .ssh && chmod 600 .ssh/authorized_keys

• Configure OpenSSH to allow Public-key authentication

sshd_config

#AuthorizedKeysFile	.ssh/authorized_keys .ssh/authorized_keys

sshd_config (man)

AUTHORIZED_KEYS FILE FORMAT
    AuthorizedKeysFile specifies the files containing public keys for public key authentication; if this option is not specified, the default is ~/.ssh/authorized_keys and
    ~/.ssh/authorized_keys2.  Each line of the file contains one key (empty lines and lines starting with a ‘#’ are ignored as comments).  Public keys consist of the following
    space-separated fields: options, keytype, base64-encoded key, comment.  The options field is optional.  The supported key 
types are:

          [email protected]
          ecdsa-sha2-nistp256
          ecdsa-sha2-nistp384
          ecdsa-sha2-nistp521
          [email protected]
          ssh-ed25519
          ssh-dss
          ssh-rsa

    The comment field is not used for anything (but may be convenient for the user to identify the key).

Example files

# First public key authorized
ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEBiBqpWXhPTH9RIo9UR3ED9xUv6O/SqpWRn16UH/gHD TEXT@TEXT

# Additional public key authorized
ssh-rsa .../...

# additional public key authorized  with ip restriction
from="10.22.33.45",command="/path/to/executable argument" ssh-rsa key name

# Additonal public key authroized with also no port forwarding
from="10.22.33.45",command="/path/to/executable argument",no-port-forwarding,no-x11-forwarding ssh-rsa ...

Additional information about format key:

https://serverfault.com/questions/526399/why-do-my-two-ssh-public-keys-have-the-same-beginning/526404

https://tools.ietf.org/html/rfc4253

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQ...
      |  "ssh-rsa"   |exponent|   modulus

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFKy...
          |   "ssh-ed25519"   |   32 byte public key

Errors

sshd logs

Apr 26 11:45:37 ip-10-10-10-10.eu-west-1.compute.internal sshd[18174]: Authentication refused: bad ownership or modes for file /home/your_user/.ssh/authorized_keys

Activities

• Configure OpenSSH to allow Public-key authentication

Related terms

• sftp configuration
• expiry-time in OpenSSH 7.7 (2018)
• ssh-import-id
• AuthenticationMethods
• visudo
• ~/.ssh/id_ed25519.pub
• cloud-init

See also

• ~/.ssh/authorized keys
• ssh-copy-id, ~/.ssh/id_ed25519.pub, ~/.ssh/authorized_keys, Public keys
• OpenSSH (changelog): /etc/ssh/sshd_config | /etc/ssh/ssh_config | ~/.ssh/ | openSSL | sshd logs | sftp | scp | authorized_keys | ssh-keygen | ssh-keyscan | ssh-add | ssh-agent | ssh | Ssh -O stop | ssh-copy-id | CheckHostIP | UseKeychain, OpenSSF, ~/.ssh/authorized_keys