:return: Path to the .ssh/config file - usually <home>/.ssh/config

def _get_ssh_config_file(opts):
    '''
    :return: Path to the .ssh/config file - usually <home>/.ssh/config
    '''
    ssh_config_file = opts.get('ssh_config_file')
    if not os.path.isfile(ssh_config_file):
        raise IOError('Cannot find SSH config file')
    if not os.access(ssh_config_file, os.R_OK):
        raise IOError('Cannot access SSH config file: {}'.format(ssh_config_file))
    return ssh_config_file