https://blog.wongcw.com/2019/11/26/%e6%ad%90%e6%b4%b2ripe-ncc%e5%ae%a3%e5%b8%83%e5%b7%b2%e6%95%a3%e7%9b%a1%e5%85%a8%e7%90%83%e6%9c%80%e5%be%8c%e4%b8%80%e6%89%b9ipv4%e5%9c%b0%e5%9d%80/