Gestion de l’heure système

La synchronisation de l’horloge système est essentielle pour l’analyse des logs. Le protocole NTP est utilisé pour fournir un horodatage correct.

Commande timedatectl

La commande timedatectl affiche les paramètres d’horodatage :

# timedatectl
               Local time: Sun 2024-09-22 03:46:12 EDT
           Universal time: Sun 2024-09-22 07:46:12 UTC
                 RTC time: Sun 2024-09-22 07:46:12
                Time zone: America/Toronto (EDT, -0400)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

Afficher la BDD des fuseaux horaires :

# timedatectl list-timezones
[...]
Europe/Rome
Europe/Samara
Europe/Saratov
Europe/Simferopol
Europe/Sofia
Europe/Stockholm
[...]

Appliquer un fuseau horaire :

# timedatectl set-timezone Europe/Stockholm

Changer l’heure :

# timedatectl set-time 13:37:00

Désactiver la synchronisation NTP (en cas d’echec pour changer manuellement l’heure) :

# timedatectl set-ntp false

Parametrage interactif avec tzselect

Configurer une time-zone avec tzselect :

# tzselect

Please identify a location so that time zone rules can be set correctly.
Please select a continent, ocean, "coord", or "TZ".
1) Africa           5) Atlantic Ocean        9) Pacific Ocean
2) Americas         6) Australia            10) coord - I want to use geographical coordinates.
3) Antarctica       7) Europe               11) TZ - I want to specify the timezone using the Posix TZ format.
4) Asia             8) Indian Ocean
#? 7

Please select a country whose clocks agree with yours.
1) Albania                 8) Bulgaria         15) Germany       22) Italy           29) Moldova           36) Portugal     43) Spain                  50) Åland Islands
2) Andorra                 9) Croatia          16) Gibraltar     23) Jersey          30) Monaco            37) Romania      44) Svalbard & Jan Mayen
3) Austria                10) Czech Republic   17) Greece        24) Latvia          31) Montenegro        38) Russia       45) Sweden
4) Belarus                11) Denmark          18) Guernsey      25) Liechtenstein   32) Netherlands       39) San Marino   46) Switzerland
5) Belgium                12) Estonia          19) Hungary       26) Lithuania       33) North Macedonia   40) Serbia       47) Turkey
6) Bosnia & Herzegovina   13) Finland          20) Ireland       27) Luxembourg      34) Norway            41) Slovakia     48) Ukraine
7) Britain (UK)           14) France           21) Isle of Man   28) Malta           35) Poland            42) Slovenia     49) Vatican City
#? 14

The following information has been given:

        France

Therefore TZ='Europe/Paris' will be used.
Selected time is now:   Sun Sep 22 09:49:22 CEST 2024.
Universal Time is now:  Sun Sep 22 07:49:22 UTC 2024.
Is the above information OK?
1) Yes
2) No
#? 1

You can make this change permanent for yourself by appending the line
        TZ='Europe/Paris'; export TZ
to the file '.profile' in your home directory; then log out and log in again.

Here is that TZ value again, this time on standard output so that you
can use the /usr/bin/tzselect command in shell scripts:
Europe/Paris

service chronyd

Le service chronyd se base sur une horloge temps réel (RTC) locale en la synchronisant avec des serveurs NTP configurés dans /etc/chrony.conf.

L’option iburst permet de réduire le décalage de synchromisation entre les horloges.

Fichier de configuration /etc/chrony.conf :

server my.NTP.server.org iburst

Redémarrez le service après avoir modifier l’adresse du serveur NTP :

# systemctl restart chronyd

Pour vérifier que le système utilise le bon serveur NTP pour synchroniser l’horloge système :

  .-- 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
===============================================================================
^+ time.cloudflare.com           3  10   377   239   -305us[ -305us] +/-   17ms
^+ 10-42-42-22.cpe.distr>        1  10   377   275   +348us[ +348us] +/- 7268us
^* 10-42-42-22.cpe.distr>        1  10   377  1029   -223us[ -322us] +/- 7161us
^- ntp1.yow.accuris.ca           2  10   377   721  +7001us[+7001us] +/-   45ms

/!\ Résumé des commandes

Commandes :

# timedatectl                               // Afficher les information de l'horodatage
# timedatectl list-timezones                // Lister les fuseaux
# timedatectl set-timezone Europe/Stockholm // Changer le fuseau
# timedatectl set-time 13:37:00             // Changer l'heure
# timedatectl set-ntp false                 // En cas d'echec pour changer l'heure

# systemctl restart chronyd                 // Charger la config
# chronyc sources -v                        // Verifier la config

# tzselect                                  // Configurer le fuseau horaire

Fichiers :

/etc/chrony.conf

server my.NTP.server.org iburst   // parametrage d'un serveur NTP dans le fichier /etc/chrony.conf

Cas Pratiques

Fuseau horaire

Sélection du fuseau horaire approprié pour la base Antarctique Troll.

[root@SERVER01 ~]# tzselect

Please identify a location so that time zone rules can be set correctly.
Please select a continent, ocean, "coord", or "TZ".
1) Africa         5) Atlantic Ocean      9) Pacific Ocean
2) Americas       6) Australia          10) coord - I want to use geographical coordinates.
3) Antarctica     7) Europe             11) TZ - I want to specify the timezone using the Posix TZ format.
4) Asia           8) Indian Ocean
#? 3

Please select a country whose clocks agree with yours.
1) Antarctica
2) Australia
#? 1

Please select one of the following timezones.
1) Casey        5) Rothera                 9) Papua New Guinea (most areas), Chuuk, Yap, Dumont d'Urville       
2) Davis        6) Troll                  10) Syowa
3) Mawson       7) Vostok
4) Palmer       8) New Zealand time       
#? 6

The following information has been given:

        Antarctica
        Troll

Therefore TZ='Antarctica/Troll' will be used.
Selected time is now:   Sun Sep 22 09:57:55 +02 2024.
Universal Time is now:  Sun Sep 22 07:57:55 UTC 2024.
Is the above information OK?
1) Yes
2) No
#? 1

You can make this change permanent for yourself by appending the line
        TZ='Antarctica/Troll'; export TZ
to the file '.profile' in your home directory; then log out and log in again.

Here is that TZ value again, this time on standard output so that you
can use the /usr/bin/tzselect command in shell scripts:
Antarctica/Troll

Mise à jour du fuseau horaire sur Antarctica/Troll :

[root@SERVER01 ~]# timedatectl set-timezone Antarctica/Troll

Vérification :

[root@Redhat1-Test1 ~]# timedatectl
               Local time: Sun 2024-09-22 10:00:21 +02
           Universal time: Sun 2024-09-22 08:00:21 UTC
                 RTC time: Sun 2024-09-22 08:00:21
                Time zone: Antarctica/Troll (+02, +0200)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

Configurer chronyd

Configuration de chronyd en éditant le fichier /etc/chrony.conf pour synchroniser l’heure du système avec le serveur NTP atomic-clock.org :

[root@SERVER01 ~]# vim /etc/chrony.conf

# Use public servers from the pool.ntp.org project.

server atomic-clock.org iburst
[...]

Activer la synchronisation :

[root@SERVER01 ~]# sudo timedatectl set-ntp true

Vérification :

[root@SERVER01 ~]# timedatectl

               Local time: Sun 2024-09-22 10:53:28 +02
           Universal time: Sun 2024-09-22 08:53:28 UTC
                 RTC time: Sun 2024-09-22 08:53:28
                Time zone: Antarctica/Troll (+02, +0200)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

Vérification que le serveur est synchronisé, l’astérisque (*) indique que l’heure du système local est correctement synchronisée avec la source de temps NTP :

[root@SERVER01 ~]# 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
===============================================================================
^* 172-xxx-yyy-42.cpe.distr>     1  10   377    43   +188us[ +209us] +/- 7291us

Documentation

MAN timedatectl(1)
MAN tzselect(8)
MAN chronyd(8)
MAN chrony.conf(5)
MAN chronyc(1)

http://www.ntppool.org/
http://www.iana.org/time-zones