Authenticate a user by the external auth module specified in load.
        Return True on success or False on failure.

def authenticate_eauth(self, load):
        '''
        Authenticate a user by the external auth module specified in load.
        Return True on success or False on failure.
        '''
        if 'eauth' not in load:
            log.warning('Authentication failure of type "eauth" occurred.')
            return False

        if load['eauth'] not in self.opts['external_auth']:
            log.warning('The eauth system "%s" is not enabled', load['eauth'])
            log.warning('Authentication failure of type "eauth" occurred.')
            return False

        # Perform the actual authentication. If we fail here, do not
        # continue.
        if not self.time_auth(load):
            log.warning('Authentication failure of type "eauth" occurred.')
            return False

        return True