chronyd //ntp服务，是一个进程，需要百度一下，了解一下

使用chrony代替ntp同步时间 ： //参考此3个链接

[root@lb01 ~]# yum install chrony -y[root@lb01 ~]# rpm -qa|grep chronychrony-2.1.1-2.el6_8.x86_64[root@lb01 ~]# cat /etc/chrony.conf                           //默认配置文件# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).server 0.rhel.pool.ntp.org iburstserver 1.rhel.pool.ntp.org iburstserver 2.rhel.pool.ntp.org iburstserver 3.rhel.pool.ntp.org iburst# Ignore stratum in source selection.stratumweight 0# Record the rate at which the system clock gains/losses time.driftfile /var/lib/chrony/drift# In first three updates step the system clock instead of slew# if the adjustment is larger than 10 seconds.makestep 10 3# Enable kernel synchronization of the real-time clock (RTC).rtcsync# Allow NTP client access from local network.#allow 192.168/16# Serve time even if not synchronized to any NTP server.#local stratum 10# Specify file containing keys for NTP and command authentication.keyfile /etc/chrony.keys# Specify key number for command authentication.commandkey 1# Generate new command key on start if missing.generatecommandkey# Disable logging of client accesses.noclientlog# Send message to syslog when clock adjustment is larger than 0.5 seconds.logchange 0.5# Specify directory for log files.logdir /var/log/chrony# Select which information is logged.#log measurements statistics tracking

Linux centos7 下使用timedatectl命令时间时区操作详解：

CentOS 6 时间，时区，设置修改及时间同步： 在centos7上执行 timedatectl set-ntp true //使用网络时间同步在CentOS 6版本，时间设置有date、hwclock命令，从CentOS 7开始，使用了一个新的命令timedatectl。

[root@lb01 ~]# date +%F\ %T 2018-12-07 23:31:37[root@lb01 ~]# grep '^[a-Z]' /etc/chrony.confserver ntp1.aliyun.com iburstserver time.nist.gov iburstserver time.windows.com iburst              //增加以上三个stratumweight 0driftfile /var/lib/chrony/driftmakestep 10 3rtcsyncallow 192.168.10.0/16                  //允许这个网段的来同步自己的时间keyfile /etc/chrony.keyscommandkey 1generatecommandkeynoclientloglogchange 0.5logdir /var/log/chrony[root@lb01 ~]# service chronyd startStarting chronyd:                                          [  OK  ][root@lb01 ~]# service chronyd statuschronyd (pid  1823) is running...[root@lb01 ~]# chronyc -a makestep                          //设置完时区后，强制同步下系统时钟：200 OK200 OK[root@lb01 ~]# chkconfig chronyd on  [root@lb01 ~]# date +%F\ %T                 //此时的时间与当时时间是准的         2018-12-07 15:38:44[root@lb01 ~]#  ps -ef|grep chronychrony     1823      1  0 15:34 ?        00:00:00 /usr/sbin/chronyd -u chronyroot       1849   1707  0 15:46 pts/0    00:00:00 grep --color=auto chrony[root@lb01 ~]# netstat -lntupActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      1562/sshd           tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      1638/master         tcp        0      0 :::22                       :::*                        LISTEN      1562/sshd           tcp        0      0 ::1:25                      :::*                        LISTEN      1638/master         udp        0      0 127.0.0.1:323               0.0.0.0:*                               1823/chronyd        udp        0      0 ::1:323                     :::*                                    1823/chronyd  [root@lb01 ~]# chronyc sources -v   //验证服务端是否能同步时间210 Number of sources = 3  .-- Source mode  '^' = server, '=' = peer, '#' = local clock. / .- Source state '*' = current synced, '+' = combined , '-' = not combined,| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.||                                                 .- xxxx [ yyyy ] +/- zzzz||      Reachability register (octal) -.           |  xxxx = adjusted offset,||      Log2(Polling interval) --.      |          |  yyyy = measured offset,||                                \     |          |  zzzz = estimated error.||                                 |    |           \MS Name/IP address         Stratum Poll Reach LastRx Last sample===============================================================================^* 120.25.115.20                 2   8   377   496  -2413us[-2900us] +/-   22ms^? time-a-g.nist.gov             0   9     0   10y     +0ns[   +0ns] +/-    0ns^- 52.168.138.145                2   8   377    97    +16ms[  +16ms] +/-  182ms以上服务器端配置完成

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lb01作为服务器端 1b02 作为客户端，来同步他的时间[root@lb02 ~]# date +%F\ %T          //此时时间是不准的2018-12-07 23:41:17[root@lb02 ~]# yum -y install chrony[root@lb02 ~]# grep '^[a-Z]' /etc/chrony.conf    server 192.168.10.160 iburst                  //添加这个stratumweight 0driftfile /var/lib/chrony/driftmakestep 10 3rtcsynckeyfile /etc/chrony.keyscommandkey 1generatecommandkeynoclientloglogchange 0.5logdir /var/log/chrony[root@lb02 ~]# service chronyd statuschronyd is stopped[root@lb02 ~]# service chronyd startStarting chronyd:                                          [  OK  ][root@lb02 ~]# chkconfig chronyd on[root@lb02 ~]# chronyc sources -v               //验证同步的源210 Number of sources = 1  .-- Source mode  '^' = server, '=' = peer, '#' = local clock. / .- Source state '*' = current synced, '+' = combined , '-' = not combined,| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.||                                                 .- xxxx [ yyyy ] +/- zzzz||      Reachability register (octal) -.           |  xxxx = adjusted offset,||      Log2(Polling interval) --.      |          |  yyyy = measured offset,||                                \     |          |  zzzz = estimated error.||                                 |    |           \MS Name/IP address         Stratum Poll Reach LastRx Last sample===============================================================================^? 192.168.10.160                0   8     0   10y     +0ns[   +0ns] +/-    0ns

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7.常用命令查看时间同步源：$ chronyc sources -v[root@lb02 ~]# chronyc sources210 Number of sources = 1MS Name/IP address         Stratum Poll Reach LastRx Last sample===============================================================================^? 192.168.10.160                0   8     0   10y     +0ns[   +0ns] +/-    0ns查看时间同步源状态：$ chronyc sourcestats -v[root@lb02 ~]# chronyc sourcestats -v210 Number of sources = 1                             .- Number of sample points in measurement set.                            /    .- Number of residual runs with same sign.                           |    /    .- Length of measurement set (time).                           |   |    /      .- Est. clock freq error (ppm).                           |   |   |      /           .- Est. error in freq.                           |   |   |     |           /         .- Est. offset.                           |   |   |     |          |          |   On the -.                           |   |   |     |          |          |   samples. \                           |   |   |     |          |          |             |Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev==============================================================================192.168.10.160              0   0     0     +0.000   2000.000     +0ns  4000ms设置硬件时间硬件时间默认为UTC：$ timedatectl set-local-rtc 1启用NTP时间同步：$ timedatectl set-ntp yes校准时间服务器：$ chronyc tracking[root@lb02 ~]# chronyc trackingReference ID    : 0.0.0.0 ()Stratum         : 0Ref time (UTC)  : Thu Jan  1 00:00:00 1970System time     : 0.000000000 seconds fast of NTP timeLast offset     : +0.000000000 secondsRMS offset      : 0.000000000 secondsFrequency       : 0.000 ppm fastResidual freq   : +0.000 ppmSkew            : 0.000 ppmRoot delay      : 0.000000 secondsRoot dispersion : 0.000000 secondsUpdate interval : 0.0 secondsLeap status     : Not synchronised

最后需要注意的是，配置完/etc/chrony.conf后，需重启chrony服务，否则可能会不生效。

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**centos7系统**[root@localhost ~]# cat /etc/redhat-release CentOS Linux release 7.1.1503 (Core)  24  yum install chrony -y   25  rpm -qa|grep chrony   26  date   27  cat /etc/chrony.conf   28  grep '^[a-Z]' /etc/chrony.conf   29  vim /etc/chrony.conf   30  grep '^[a-Z]' /etc/chrony.conf   32  systemctl start chronyd   33  systemctl status chronyd   34  chronyc -a makestep    35  systemctl enable chronyd   36  date +%F\ %T     37  date -s 18:00:00             //我设置的错误的时间   38  date +%F\ %T     39  ps -ef|grep chrony   40  netstat -lntup   41  chronyc sources -v   42  date +%F\ %T     43  chronyc -a makestep     [root@localhost ~]# timedatectl status      Local time: Mon 2018-12-10 18:01:32 CST  Universal time: Mon 2018-12-10 10:01:32 UTC        RTC time: Mon 2018-12-10 10:43:59        Timezone: Asia/Shanghai (CST, +0800)     NTP enabled: yesNTP synchronized: no              //表示，还没有进行时间同步 RTC in local TZ: no      DST active: n/a[root@localhost ~]# date +%F\ %T           //此时的时间是正确的        2018-12-10 18:44:57[root@localhost ~]# timedatectl status            Local time: Mon 2018-12-10 18:45:44 CST  Universal time: Mon 2018-12-10 10:45:44 UTC        RTC time: Mon 2018-12-10 10:45:43        Timezone: Asia/Shanghai (CST, +0800)     NTP enabled: yesNTP synchronized: yes                  //表示已经同步上了 RTC in local TZ: no      DST active: n/a重新搞了个从的服务器（客户端）修改了主服务器的配置，然后重启了chronyd服务[root@localhost ~]# grep '^[a-Z]' /etc/chrony.conf    server ntp1.aliyun.com iburstserver time.nist.gov iburstdriftfile /var/lib/chrony/driftmakestep 1.0 3rtcsyncallow 192.168.10.0/16logdir /var/log/chrony在从服务器上直接安装配置好[root@localhost ~]# grep '^[a-Z]' /etc/chrony.conf server 192.168.10.129 iburstdriftfile /var/lib/chrony/driftmakestep 1.0 3rtcsynclogdir /var/log/chrony[root@localhost ~]# timedatectl            Local time: Mon 2018-12-10 18:56:19 CST  Universal time: Mon 2018-12-10 10:56:19 UTC        RTC time: Mon 2018-12-10 10:56:19        Timezone: Asia/Shanghai (CST, +0800)     NTP enabled: yesNTP synchronized: yes           //成功了，时间和主服务器上是相同的 RTC in local TZ: no      DST active: n/a