CentOS7防火墙命令有变化：
CentOS7： systemctl status firewalld.service 查看防火墙状态
systemctl stop firewalld.service 本次访问关闭防火墙
systemctl disable firewalld.service 从下次开始关闭防火墙
systemctl enable firewalld.service 打开防火墙
关于网络的配置最后用：systemctl restart network
CentOS6: service iptables status 查看防火墙状态
service iptables start 临时开启防火墙
service iptables stop 临时关闭防火墙
chkconfig iptables --list 查看防火墙开机启动状态
chkconfig iptables on 开启防火墙开机启动
chkconfig iptables off 关闭防火墙开机启动