Enabling RSA key-based authentication on UNIX and Linux operating systems

Well in one of my previous blog, I explained how to create the SSH Public / Private key pair.  In todays session, I will be explaining you all how to Enable the authentication on Unix / Linux Server, based on these generated RSA key pair.  You can use RSA key-based authentication as an alternative to simple password authentication.

  1. Enable key-based authentication in the '/etc/ssh' directory on the server.
    Ensure that the following lines exist in the 'sshd_config' file:

    # Should we allow Identity (SSH version 1) authentication?
        RSAAuthentication yes
      
        # Should we allow Pubkey (SSH version 2) authentication?
        PubkeyAuthentication yes
            
        # Where do we look for authorized public keys?
    # If it doesn't start with a slash, then it is
    # relative to the user's home directory
    AuthorizedKeysFile .ssh / authorized_keys
     

  2. Also, in the same 'sshd_config' file, add 'LogLevel DEBUG' in '# Logging' section.  This would help you debug the errors in the default log file ' / var / log / auth.log'.

  3. Now add the Public Key of yours into the 'authorized_keys' file of server located at '$HOME / .ssh / '.

    $ vim .ssh / authorized_keys

    Make a note, the public key should be in OpenSSH format and not SSH2. Refer https://tutorialinux.com/convert-ssh2-openssh/ to convert it if needed.

  4. Finally, restart the SSH service with command :

    $ sudo service sshd restart

     

Done ! !  We are all set to connect to Server based on our Public / Private Key pair and no need to rely on Password anymore.

 

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