linux开启与关闭防火墙
service iptables stop/start/status
在CentOS 7或RHEL 7或Fedora中防火墙由firewalld来管理
关闭防火墙命令：systemctl stop firewalld.service
开启防火墙：systemctl start firewalld.service
关闭开机自启动：systemctl disable firewalld.service
开启开机启动：systemctl enable firewalld.service