#先检查是否安装了iptables
service iptables status
#安装iptables
yum install -y iptables
#升级iptables 
yum update iptables
#安装iptables-servic

yum -y install ntp
systemctl status ntpd.service    #查看服务状态
systemctl enable ntpd.service   #开机自启动
systemctl start ntpd.service