CentOS之service iptables stop 显示not loaded

停止firewalld服务
停止防火墙，并禁用这个服务

sudo systemctl stop firewalld.service
sudo systemctl disable firewalld.service

安装iptables
如果你要改用iptables的话，需要安装iptables服务：

#安装
sudo yum install iptables-services
#开启iptables
sudo systemctl enable iptables
sudo systemctl enable ip6tables
#启动服务
sudo systemctl start iptables
sudo systemctl start ip6tables