历史Linux镜像创建的ECS云服务器，可能存在NTP没有配置，YUM没有配置，还可能存在近暴漏较高的安全漏洞，请按照以下步骤进行修复，可以让您的云服务器更加安全，还可以使用阿里云提供的YUM服务进行安装软件，可以使用免费的阿里云提供的NTP进行时间同步。
　　1. 配置NTP
　　不区分发行版，先备份 /etc/ntp.conf，然后将其内容替换为如下:
# ntp.conf
#
# ntpd config for aliyun ecs.
#
# 6LAN+6LAN+3WAN
#               shijun.cao@alibaba-inc.com
#               2014.8.11
#
driftfile  /var/lib/ntp/drift
pidfile   /var/run/ntpd.pid
logfile /var/log/ntp.log
# Access Control Support
restrict    default ignore
restrict -6 default ignore
restrict 127.0.0.1
restrict 192.168.0.0 mask 255.255.0.0 nomodify notrap nopeer noquery
restrict 172.16.0.0 mask 255.240.0.0 nomodify notrap nopeer noquery
restrict 100.64.0.0 mask 255.192.0.0 nomodify notrap nopeer noquery
restrict 10.0.0.0 mask 255.0.0.0 nomodify notrap nopeer noquery
restrict ntp1.aliyun.com nomodify notrap nopeer noquery
restrict ntp2.aliyun.com nomodify notrap nopeer noquery
restrict ntp3.aliyun.com nomodify notrap nopeer noquery
restrict ntp4.aliyun.com nomodify notrap nopeer noquery
restrict ntp5.aliyun.com nomodify notrap nopeer noquery
restrict ntp6.aliyun.com nomodify notrap nopeer noquery
# local clock
server 127.127.1.0
fudge  127.127.1.0 stratum 10
#public ntp server
server ntp1.aliyun.com iburst minpoll 4 maxpoll 10
server ntp2.aliyun.com iburst minpoll 4 maxpoll 10
server ntp3.aliyun.com iburst minpoll 4 maxpoll 10
server ntp4.aliyun.com iburst minpoll 4 maxpoll 10
server ntp5.aliyun.com iburst minpoll 4 maxpoll 10
server ntp6.aliyun.com iburst minpoll 4 maxpoll 10
#Private ntp server
server ntp1.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp2.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp3.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp4.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp5.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp6.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
#New private ntp server
server ntp7.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp8.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp9.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp10.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp11.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10
server ntp12.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10