1.关闭防火墙
1.1 停止firewall
systemctl stop firewalld.service
1.2 禁用firewall
systemctl disable firewalld.service
2.设置iptables
2.1.安装iptables
yum install iptables-services -y
2.2.修改iptables规则
修改配置文件 /etc/sysconfig/iptables，如允许访问MySQL数据库端口，则增加规则：
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT
2.3 重启iptables
systemctl restart iptables.service
2.4 开机启动iptables
systemctl enable iptables.service
