-.Ss SSH protocol version 2
-When a user connects using protocol version 2,
-similar authentication methods are available.
-Using the default values for
-.Cm PreferredAuthentications ,
-the client will try to authenticate first using the hostbased method;
-if this method fails, public key authentication is attempted,
-and finally if this method fails, keyboard-interactive and
-password authentication are tried.
-.Pp
-The public key method is similar to RSA authentication described
-in the previous section and allows the RSA or DSA algorithm to be used:
-The client uses his private key,
-.Pa ~/.ssh/id_dsa
-or
-.Pa ~/.ssh/id_rsa ,
-to sign the session identifier and sends the result to the server.
-The server checks whether the matching public key is listed in
-.Pa ~/.ssh/authorized_keys
-and grants access if both the key is found and the signature is correct.
-The session identifier is derived from a shared Diffie-Hellman value
-and is only known to the client and the server.
-.Pp
-If public key authentication fails or is not available, a password
-can be sent encrypted to the remote host to prove the user's identity.
-.Pp
-Additionally,
-.Nm
-supports hostbased or challenge response authentication.
-.Pp
-Protocol 2 provides additional mechanisms for confidentiality
-(the traffic is encrypted using AES, 3DES, Blowfish, CAST128 or Arcfour)
-and integrity (hmac-md5, hmac-sha1, hmac-ripemd160).
-Note that protocol 1 lacks a strong mechanism for ensuring the
-integrity of the connection.