4行命令，设置80和443只允许CF访问，防止被扫

iptables -I INPUT -p tcp --dport 80 -j DROP
iptables -I INPUT -p tcp --dport 443 -j DROP
curl https://www.cloudflare.com/ips-v4|awk '{print"iptables -I INPUT -s "$0" -p tcp --dport 80 -j ACCEPT"}'|sh
curl https://www.cloudflare.com/ips-v4|awk '{print"iptables -I INPUT -s "$0" -p tcp --dport 443 -j ACCEPT"}'|sh