AlmaLinux9では時刻同期にChronyサービスがデフォルトでインストールされています。基本的にここではNTPサーバとしてではなく、NTPクライアントとして設定することを前提としています。
chronyの設定ファイルは/etc/chrony.confです。
# cat /etc/chrony.conf # Use public servers from the pool.ntp.org project. # Please consider joining the pool (https://www.pool.ntp.org/join.html). pool 2.almalinux.pool.ntp.org iburst # Use NTP servers from DHCP. sourcedir /run/chrony-dhcp # 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 192.168.0.0/16 # Serve time even if not synchronized to a time source. #local stratum 10 # Require authentication (nts or key option) for all NTP sources. #authselectmode require # Specify file containing keys for NTP authentication. keyfile /etc/chrony.keys # Save NTS keys and cookies. ntsdumpdir /var/lib/chrony # Insert/delete leap seconds by slewing instead of stepping. #leapsecmode slew # 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 |
指定したい好みのNTPサーバがあればそれを指定すれば良いのですが、基本的に何も設定は触らなくて大丈夫です。このままでも時刻同期できます。次のコマンドで同期の状態を確認できます。
# chronyc tracking Reference ID : 5EC69F0B (nts1.time.nl) Stratum : 2 Ref time (UTC) : Fri Apr 21 07:18:53 2023 System time : 0.001896059 seconds fast of NTP time Last offset : +0.000915421 seconds RMS offset : 0.003955518 seconds Frequency : 21.477 ppm slow Residual freq : +0.365 ppm Skew : 3.018 ppm Root delay : 0.202217773 seconds Root dispersion : 0.002127213 seconds Update interval : 195.7 seconds Leap status : Normal |
実際に時刻同期を行っているサーバは以下のコマンドで確認できます。同期を行っているサーバとのところで*がついています。
# chronyc sources MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^+ ntp2.belbone.be 2 7 377 129 +440us[+1354us] +/- 137ms ^* nts1.time.nl 1 6 377 129 +15ms[ +16ms] +/- 105ms ^+ vmi586073.contaboserver.> 2 7 377 63 -8298us[-8298us] +/- 133ms ^+ mx.ae9.eu 2 6 377 0 -6169us[-6169us] +/- 190ms |