Introduction to chrony time synchronization software

This article is shared from Tianyi Cloud Developer CommunityIntroduction to chrony time synchronization software》, author: Liu **** Su

chronyIt is the network time protocolNTPThe general implementation of the system clock and`NTPServer synchronization. It supports intermittent network connections, severely blocked networks, changing temperatures and supports discontinuous operation and can operate on virtual machines under various conditions.

This article introduceschronyThe installation and use of the tool includes two nodes: one as a time server and the other as a client.

Run the following command to installchrony：

[root@kvm ~]# yum install chrony
[root@kvm ~]# rpm -ql chrony
/etc/NetworkManager//20-chrony-dhcp
/etc/NetworkManager//20-chrony-onoffline
/etc/
/etc/
/etc/dhcp//
/etc//chrony
/etc/sysconfig/chronyd
/usr/bin/chronyc
/usr/lib/.build-id
/usr/lib/.build-id/38
/usr/lib/.build-id/38/1d3a324ce66865ba879dfa43d49e0e0c1e2c41
/usr/lib/.build-id/43
/usr/lib/.build-id/43/444c816fcf0802c43011f282afaf9feded4c56
/usr/lib/systemd//50-
/usr/lib/systemd/system/chrony-[email protected]
/usr/lib/systemd/system/chrony-[email protected]
/usr/lib/systemd/system/chrony-
/usr/lib/systemd/system/
/usr/libexec/chrony-helper
/usr/sbin/chronyd
/usr/share/doc/chrony
/usr/share/doc/chrony/FAQ
/usr/share/doc/chrony/NEWS
/usr/share/doc/chrony/README
/usr/share/doc/chrony/
/usr/share/licenses/chrony
/usr/share/licenses/chrony/COPYING
/usr/share/man/man1/chronyc.1.gz
/usr/share/man/man5/.5.gz
/usr/share/man/man8/chronyd.8.gz
/var/lib/chrony
/var/lib/chrony/drift
/var/lib/chrony/rtc
/var/log/chrony

The configuration file is shown below:

[root@kvm ~]# cat /etc/
pool 2. iburst

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Enable hardware timestamping on all interfaces that support it.
#hwtimestamp *

# Increase the minimum number of selectable sources required to adjust
# the system clock.
#minsources 2

# Allow NTP client access from local network.
allow 0/0

# Serve time even if not synchronized to a time source.
local stratum 10

# Specify file containing keys for NTP authentication.
keyfile /etc/

# Get TAI-UTC offset and leap seconds from the system tz database.
leapsectz right/UTC

# Specify directory for log files.
logdir /var/log/chrony

# Select which information is logged.
#log measurements statistics tracking

in:

pool: is the external clock source address
rtcsync: Turn on the synchronization mechanism of the hardware clock. The Linux kernel synchronizes the system clock to the hardware clock every 11 minutes.
local stratum 10: When the external clock source is unavailable, the service will continue to be provided based on the local clock.
allow 0/0: cidr for allowed client

Check the status after starting the service:

[root@kvm ~]# systemctl start chronyd
[root@kvm ~]#
[root@kvm ~]#
[root@kvm ~]# systemctl status chronyd
●  - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2023-09-08 19:02:50 CST; 2min 43s left
     Docs: man:chronyd(8)
           man:(5)
  Process: 11542 ExecStopPost=/usr/libexec/chrony-helper remove-daemon-state (code=exited, status=0/SUCCESS)
  Process: 11552 ExecStartPost=/usr/libexec/chrony-helper update-daemon (code=exited, status=0/SUCCESS)
  Process: 11547 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 11550 (chronyd)
    Tasks: 1 (limit: 52427)
   Memory: 924.0K
   CGroup: //
           └─11550 /usr/sbin/chronyd

Sep 08 19:02:50 kvm chronyd[11550]: chronyd version 4.2 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 +DEBUG)
Sep 08 19:02:50 kvm chronyd[11550]: Frequency 1.633 +/- 0.046 ppm read from /var/lib/chrony/drift
Sep 08 19:02:50 kvm chronyd[11550]: Using right/UTC timezone to obtain leap second data
Sep 08 19:02:50 kvm systemd[1]: Started NTP client/server.
Sep 08 19:02:55 kvm chronyd[11550]: Selected source 36.110.233.85 (2.)
Sep 08 19:02:55 kvm chronyd[11550]: System clock wrong by -791.549636 seconds
Sep 08 18:49:44 kvm chronyd[11550]: System clock was stepped by -791.549636 seconds
Sep 08 18:49:44 kvm chronyd[11550]: System clock TAI offset set to 37 seconds
Sep 08 18:50:49 kvm chronyd[11550]: Selected source 119.28.206.193 (2.)
Sep 08 18:54:07 kvm chronyd[11550]: Source 81.16.177.123 replaced with 78.46.102.180 (2.)
[root@kvm ~]#
[root@kvm ~]# netstat -tunlp |grep chrony
udp        0      0 0.0.0.0:123             0.0.0.0:*                           11550/chronyd
udp        0      0 127.0.0.1:323           0.0.0.0:*                           11550/chronyd
udp6       0      0 ::1:323                 :::*                                11550/chronyd
[root@kvm ~]#
[root@kvm ~]# chronyc sources -v

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current best, '+' = combined, '-' = not combined,
| /             'x' = may be in error, '~' = too variable, '?' = unusable.
||                                                 .- 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
===============================================================================
^- 79.133.44.136                 1   6   377    56    -10ms[  -10ms] +/-  138ms
^-            2   6    33    55    +17ms[  +17ms] +/-  119ms
^* 119.28.206.193                2   6   377    60  +1706us[+2327us] +/-   40ms
^+ 36.110.233.85                 2   6   377    58  -1324us[-1324us] +/-   68ms

chronyDaemon monitoring isudpThe agreement123and323port.

Installed on the client nodechronyAfter that, modify the configuration file as follows:

[root@node1 ~]# cat /etc/
server 172.24.21.221 iburst

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 3600 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Enable hardware timestamping on all interfaces that support it.
#hwtimestamp *

# Increase the minimum number of selectable sources required to adjust
# the system clock.
#minsources 2

# Allow NTP client access from local network.
#allow 192.168.0.0/16

# Serve time even if not synchronized to a time source.
#local stratum 10

# Specify file containing keys for NTP authentication.
#keyfile /etc/

# Specify directory for log files.
logdir /var/log/chrony

# Select which information is logged.
#log measurements statistics tracking

View status:

[root@node1 ~]# chronyc sources -v
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
===============================================================================
^* 172.24.21.221                 3   6   377    37  -7753ns[ +140us] +/-   29ms

chronyBy default, continuous synchronization is used to synchronize the clock, not to jump.