Ημερήσια αρχεία: 7 Ιουνίου 2017

Recently, we wanted to connect to a machine via SSH without using the default RSA key that was available in the client’s profile (~/.ssh/id_rsa).

We needed to avoid using the public key authentication method for two reasons:

1. The client did not want to share the passphrase with us
2. We did not want to move the key, not even temporarily

So, to connect via SSH while ignoring the key completely we connected using the following command

ssh -o PreferredAuthentications=keyboard-interactive,password -o PubkeyAuthentication=no user@server;

Explanation of parameters:

• -o Was used to give options in the format used in the configuration file (/etc/ssh/ssh_config). It is useful for specifying options for which there is no separate command-line flag available.
• -o PreferredAuthentications can be used to change the default order of authentication and bypass the GSSAPI-based authentication, the host-based authentication, the public key authentication and the challenge-response authentication.
  -o PreferredAuthentications=keyboard-interactive,password instructs the server to perform the authentication through the keyboard-interactive method and if that method is not available to use the password method.
  The keyboard-interactive authentication method is a request for all different pieces of information needed for the authentication. The server can specify, which inputs need to be hidden when user types them and which are not.
  The password authentication is a request for a single password. There is no configuration sent by the server. So the client decides how to format the prompt.
• -o PubkeyAuthentication=no Specifies whether to try public key authentication. By setting the value to no it disables it.