NGINX网站只允许CLOUDFLARE 回源访问方法

对于使用Cloudflare的CDN的站长，需要设置服务器只允许来自CF的回源请求IP连接网站，这种其实有利于网站防御，也可以一定程度上减少被扫描发现源IP。方法如下：
在网站设置里面，配置文件，放置在server里面

location / {
  allow   173.245.48.0/20;
  allow   103.21.244.0/22;
  allow   103.22.200.0/22;
  allow   103.31.4.0/22;
  allow   141.101.64.0/18;
  allow   108.162.192.0/18;
  allow   190.93.240.0/20;
  allow   188.114.96.0/20;
  allow   197.234.240.0/22;
  allow   198.41.128.0/17;
  allow   162.158.0.0/15;
  allow   104.16.0.0/13;
  allow   104.24.0.0/14;
  allow   172.64.0.0/13;
  allow   131.0.72.0/22;
  allow   2400:cb00::/32;
  allow   2606:4700::/32;
  allow   2803:f800::/32;
  allow   2405:b500::/32;
  allow   2405:8100::/32;
  allow   2a06:98c0::/29;
  allow   2c0f:f248::/32;
  deny    all;
}

IP更新源：https://www.cloudflare.com/ips/