1/2/2024 0 Comments Utc clock ubuntuOverviewĪccuracy for a computer clock is gauged on how close the computer clock is to the Coordinated Universal Time (UTC) time standard. Also, we specify the NTP server address as host1.For a quick overview of Windows Time service, take a look at this high-level overview video.įor more information, see Accurate time for Windows Server 2016. In the above command, we use the -d option twice to print the debugging messages to the terminal. reference.c:905:(special_mode_sync) System clock wrong by 194.827846 seconds (ignored) ntp_core.c:1176:(transmit_timeout) Transmit timeout for ntp_sources.c:407:(name_resolve_handler) host1 resolved to 1 addrs ntp_sources.c:479:(resolve_sources) resolving host1 main.c:515:(main) chronyd version 3.4 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +SECHASH +IPV6 +DEBUG) We use the -Q option to query the NTP server without adjusting the system clock: $ chronyd -d -d -Q "server host1 iburst" Lastly, to test our configuration, let’s pass the -d and -Q flags to the chronyd command. We map host1 to its IP address using the /etc/hosts file. ![]() Note that we use host1 as our timeserver. We see that we have successfully added the rule and it is now persistent upon reboot.Īfterward, we load the new firewall rule with the reload option to make it active: # firewall-cmd -reloadįollowing, we allow access to the NTP server from our local subnet: $ grep ^allow /etc/nfįinally, let’s restart the chronyd service: # systemctl restart chronydįrom “host2”, we update the server directive in the /etc/nf file: $ grep ^server /etc/nf # firewall-cmd -permanent -add-service ntp Let’s see next how we can enable NTP for another node which we will call “host2”. We have seen that “host1” is syncing time with an NTP server on the internet. Time sources with lower values have higher accuracy. ![]() The Stratum column takes a value in the range of 1 to 15. Whereas the plus sign + indicates that two other servers can also be considered for synchronization. The asterisk * means that our system is currently synchronized with. The S column gives us details about the state of the NTP source. Let’s understand the meaning of two important columns: MS Name/IP address Stratum Poll Reach LastRx Last sample | / '?' = unreachable, 'x' = time may be in error, '~' = time too variable. Source state '*' = current synced, '+' = combined, '-' = not combined, Source mode '^' = server, '=' = peer, '#' = local clock. Now that chronyd is running, let’s explore how we can monitor our time synchronization. Loaded: loaded (/usr/lib/systemd/system/rvice enabled vendor preset: enabled)Īctive: active (running) since Fri 21:44:52 EEST 26s ago In the above, systemctl with the enable option configures chronyd to start automatically after the server reboot.įinally, let’s check the status of the chronyd service: $ systemctl status chronyd Next, let’s start and enable the service: # systemctl start chronyd Note that we keep the iburst default option for quicker initial synchronization. Using our text editor, we comment out the default NTP servers’ lines by inserting the # sign at the beginning. To illustrate, let’s replace the NTP servers with the ones of our choice based on our preferred time zone: $ grep "server " /etc/nf We notice that our Local time is now in the correct Time zone, while the default RTC time is in UTC. We use the grep command to match all the lines starting with Europe/.įinally, as a superuser, let’s set our local time zone and print the timedatectl output: # timedatectl set-timezone Europe/Athens timedatectl Then we can list all the available time zones using the command timedatectl list-timezones: $ timedatectl list-timezones | grep "^Europe/" ![]() Next DST change: DST ends (the clock jumps one hour backwards) at First of all, let’s display with timedatectl our time information: $ timedatectl
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