Add an rule to csf allowed hosts
    See :func:`_access_rule`.
    1- Add an IP:
    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow 127.0.0.1
        salt '*' csf.allow 127.0.0.1 comment="Allow localhost"

def allow(ip,
        port=None,
        proto='tcp',
        direction='in',
        port_origin='d',
        ip_origin='s',
        ttl=None,
        comment=''):
    '''
    Add an rule to csf allowed hosts
    See :func:`_access_rule`.
    1- Add an IP:
    CLI Example:

    .. code-block:: bash

        salt '*' csf.allow 127.0.0.1
        salt '*' csf.allow 127.0.0.1 comment="Allow localhost"
    '''
    return _access_rule('allow',
                        ip,
                        port=port,
                        proto=proto,
                        direction=direction,
                        port_origin=port_origin,
                        ip_origin=ip_origin,
                        comment=comment)