//warning:
//Only for RJ45 (ethernet) , this code not for WIFI or GPRS or 4G.
//it can find device in the same router, not for different router.
//it can find different mask and gate ip.

//提示
//只适用于网口扫描，不适用于WIFI 或者 GPRS 或者 4G模块
//可以扫描到同一路由器下的设备或者直连设备，不能跨路由器使用