https://www.cnblogs.com/kangxinxin/p/9917961.html

https://blog.csdn.net/zhangbaoanhadoop/article/details/82745769

https://blog.csdn.net/u012600104/article/details/52461793

https://jingyan.baidu.com/article/ae97a646d936ddbbfd461d02.html

https://www.sojson.com/convert/subnetmask.html