CDH之Centos7部署NTP时间同步及 NTP客户端提示unsynchronised

本配置使用五台虚拟机演示：IP配置172.17.0.102ntp服务器：本地同步标准时间172.17.0.103ntp客户端：与内部ntp服务器（85）同步时间172.17.0.104ntp客户端：与内部ntp服务器（85）同步时间查看ntp是否已经安装：rpm -q ntp如果没有安装则使用命令：yum -y install ntp 安装ntp。如果已经安装（如下）则继续：安装完成后设置ntp开

悠然大月季

4096人浏览 · 2021-10-11 11:38:07

悠然大月季 · 2021-10-11 11:38:07 发布

本配置使用三台虚拟机演示：

IP配置

172.17.0.102 ntp服务器：本地同步标准时间

172.17.0.103 ntp客户端：与内部ntp服务器（85）同步时间

172.17.0.104 ntp客户端：与内部ntp服务器（85）同步时间

查看ntp是否已经安装：rpm -q ntp
如果没有安装则使用命令：yum -y install ntp 安装ntp。

如果已经安装（如下）则继续：
安装完成后设置ntp开机启动并启动ntp，如下：

systemctl enable ntpd

systemctl start ntpd

首先设置ntp服务器（172.17.0.85）
编辑配置文件（vim /etc/ntp.conf）。

master配置：

[root@master ~]# cat /etc/ntp.conf
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).

driftfile /var/lib/ntp/drift

#新增：日志记录.
logfile /var/log/ntp.log

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1 
restrict ::1

# Hosts on local network are less restricted.
restrict 192.168.56.102 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#注释掉:集群在局域网中，不使用其他的网络时间
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst

#新增:当外部时间不可用时，使用本地时间
server 127.127.1.0
fudge 127.127.1.0 stratum 10

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography. 
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats

# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor

【！！！】这里需要注意的是，在使用ntp服务器时，如果有防火墙，则需要开启ntp服务器的udp协议123端口，否则其他虚拟机不能成功同步时间。

data1和data2配置相同。这里以data1配置为主：

# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).

driftfile /var/lib/ntp/drift

#新增：日志记录.
logfile /var/log/ntp.log

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1 
restrict ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
server 192.168.56.102 iburst

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography. 
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats

# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor

data2配置

[root@data2 ~]# cat /etc/ntp.conf 
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).

driftfile /var/lib/ntp/drift

#新增：日志记录.
logfile /var/log/ntp.log

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1 
restrict ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
server 192.168.56.102 iburst

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography. 
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats

# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor
You have new mail in /var/spool/mail/root

改完成后保存退出并重启ntp（systemctl restart ntpd）。

#重启后可以使用 查看网络中的NTP服务器
[root@master ~]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*LOCAL(0)        .LOCL.          10 l   15   64  377    0.000    0.000   0.000

#查看时间同步状态，但是需要等待几分钟才回看到同步信息
[root@master ~]# ntpstat
synchronised to local net (127.127.1.0) at stratum 11
   time correct to within 11 ms
   polling server every 64 s

#如果出现unsynchronised，稍等一会就会启动，
[root@data1 ~]# ntpstat
unsynchronised
   polling server every 64 s
   
[root@data1 ~]# ntpstat
synchronised to NTP server (192.168.56.102) at stratum 12 
   time correct to within 28 ms
   polling server every 128 s

如果unsynchronised问题没有解决，以下可参考

定位过程：

1.查询日志：/var/log/messages 查看是否有ntp失败或者fail提示。结果没有

2.查询ntp状态：service ntpd status，如下提示，依然没有fail项：

[root@data1 ~]# service ntpd status
Redirecting to /bin/systemctl status ntpd.service
● ntpd.service - Network Time Service
   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2021-10-11 10:46:07 CST; 6h ago
  Process: 987 ExecStart=/usr/sbin/ntpd -u ntp:ntp $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 989 (ntpd)
    Tasks: 1
   CGroup: /system.slice/ntpd.service
           └─989 /usr/sbin/ntpd -u ntp:ntp -g

Oct 11 10:46:07 data1 ntpd[989]: ntp_io: estimated max descriptors: 1024, in...16
Oct 11 10:46:07 data1 ntpd[989]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
Oct 11 10:46:07 data1 ntpd[989]: Listen normally on 1 lo 127.0.0.1 UDP 123
Oct 11 10:46:07 data1 ntpd[989]: Listen normally on 2 enp0s3 10.0.2.15 UDP 123
Oct 11 10:46:07 data1 ntpd[989]: Listen normally on 3 enp0s8 192.168.56.103 ...23
Oct 11 10:46:07 data1 ntpd[989]: Listen normally on 4 virbr0 192.168.122.1 U...23
Oct 11 10:46:07 data1 ntpd[989]: Listening on routing socket on fd #21 for i...es
Oct 11 10:46:07 data1 ntpd[989]: 0.0.0.0 c016 06 restart
Oct 11 10:46:07 data1 ntpd[989]: 0.0.0.0 c012 02 freq_set kernel 0.005 PPM
Oct 11 10:49:30 data1 ntpd[989]: 0.0.0.0 c615 05 clock_sync
Hint: Some lines were ellipsized, use -l to show in full.

3.查询 timedatectl：显示同步功能都是开启的

[root@data1 ~]#  timedatectl
      Local time: Mon 2021-10-11 17:45:35 CST
  Universal time: Mon 2021-10-11 09:45:35 UTC
        RTC time: Mon 2021-10-11 09:45:33
       Time zone: Asia/Shanghai (CST, +0800)
     NTP enabled: no
NTP synchronized: yes
 RTC in local TZ: no
      DST active: n/a

4.尝试与17的网络数据通信 ntpdate -u master

[root@data1 ~]# ntpdate -u master
11 Oct 17:46:21 ntpdate[28693]: adjust time server 192.168.56.102 offset -0.000115 sec

5.查询ntpstat：显示是同步的本地服务。与其他正常设备对比发现不理解stratum后面数字的含义。

[root@data1 ~]# ntpstat
unsynchronised
   polling server every 64 s

正常设备：

[root@data1 ~]# ntpstat
synchronised to NTP server (192.168.56.102) at stratum 12 
   time correct to within 28 ms
   polling server every 128 s

补充：查询stratum的含义：

层次（strata）层的概念

这些问题主要涉及到NTP的层（stratum）的概念，顶层是1，值为0时表示层数不明，层的值是累加的，比如NTP授时方向是A-〉B-〉C，假设A的stratum值是3，那么B从A获取到时间，B的stratum置为4，C从B获取到时间，C的值被置为5。一般只有整个NTP系统最顶层的服务器stratum才设为1。

NTP同步的方向是从stratum值较小的节点向较大的节点传播，如果某个NTP客户端接收到stratum比自己还要大，那么NTP客户端认为自己的时间比接受到的时间更为精确，不会进行时间的更新。

stratum根据上层server的层次而设定（+1）。

对于提供network time service provider的主机来说，stratum的设定要尽可能准确。

而作为局域网的time service provider，通常将stratum设置为10 （Stratum 10 is
conventional for unsynchronized local clocks; it is high enough that
nobody is likely to mistake it for a desirable clock to synchronize
with.），如下：

server 127.127.1.0 # local clock fudge 127.127.1.0 stratum
10
#stratum设置为其它值也是可以的，其范围为0~15
6.猜想是否是17到straum的时间较长超过11，所以本地的优先级反而高于17，所以将本地 statum尝试修改为最大值15。