centos7开启防火墙

#永久开启防火墙端口
firewall-cmd --zone=public --add-port=80/tcp --permanent

#查询端口是否开启

firewall-cmd --query-port=80/tcp

#重启防火墙
firewall-cmd --reload

关闭防火墙
systemctl stop firewalld.service

systemctl stop firewalld

取消开启启动防火墙
systemctl disable firewalld.service

#centos 6 开启防火墙

vim /etc/sysconfig/iptables

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT