问题现象
查看NTP连接的服务器发现请求超时
[root@zfr cmf]# ntpq -p
localhost: timed out, nothing received
***Request timed out
查看时间同步状态却显示正常
[root@zfr default]# ntpstat
synchronised to local net at stratum 11
time correct to within 12 ms
polling server every 64 s
问题分析
指定通过ipv4 地址获取返回值,正常显示
[root@zfr network-scripts]# ntpq -4p
remote refid st t when poll reach delay offset jitter
==============================================================================
LOCAL(0) .LOCL. 10 l 717 64 0 0.000 0.000 0.000
*100.64.252.252 10.237.42.215 5 u 83 128 377 2.406 9.419 11.271
指定通过ipv6 地址获取返回值,显示异常
[root@zfr network-scripts]# ntpq -6p
localhost: timed out, nothing received
***Request timed out
通过分析可以得出结论,操作系统开启了Ipv6 ,默认ntpq 先走Ipv6的通道。
而ECS linux 默认无法直接访问ipv6地址,因此会访问超时。
解决办法
修改sysctl.conf文件,增加一行:net.ipv6.conf.all.disable_ipv6 = 1
[root@zfr cmf]# vi /etc/sysctl.conf
# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736
# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296
net.ipv6.conf.all.disable_ipv6 = 1
结果测试
[root@zfr sysconfig]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
LOCAL(0) .LOCL. 10 l 809 64 0 0.000 0.000 0.000
100.64.252.252 .XFAC. 16 u 1951 16 0 0.000 0.000 0.000
[root@yyy-hadoop1 sysconfig]# ntpq -p
remote refid st t when poll reach delay offset jitter
=============================================================================
注:本文转自https://blog.csdn.net/zfr629/article/details/100079215
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