NTPサーバーを立ててみる。

apt -y install ntp

 vi /etc/ntp.conf

# 21行目 : デフォルト設定はコメントにして自身のタイムゾーンの NTP サーバーを追記
#pool 0.ubuntu.pool.ntp.org iburst
#pool 1.ubuntu.pool.ntp.org iburst
#pool 2.ubuntu.pool.ntp.org iburst
#pool 3.ubuntu.pool.ntp.org iburst

# Use Ubuntu's ntp server as a fallback.
#pool ntp.ubuntu.com
pool ntp.nict.jp iburst 

# 51行目 : 時刻同期を許可する範囲を追記
restrict 10.0.0.0 mask 255.255.255.0 nomodify notrap

systemctl restart ntp

root@ntp:~# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 ntp.nict.jp     .POOL.          16 p    -   64    0    0.000   +0.000   0.000
*ntp-a2.nict.go. .NICT.           1 u   44   64    3   10.003   -0.017   0.128
+ntp-a3.nict.go. .NICT.           1 u   44   64    3   10.049   -0.024   0.115
-ntp-k1.nict.jp  .NICT.           1 u   41   64    3    9.243   -0.039   0.116
-ntp-b2.nict.go. .NICT.           1 u   41   64    3    9.940   -0.135   0.012
+ntp-b3.nict.go. .NICT.           1 u   39   64    3    9.848   -0.147   0.020

apt remove ntp

apt -y install chrony

vim /etc/chrony/chrony.conf

# 20行目 : デフォルト設定はコメントにして自身のタイムゾーンの NTP サーバーを追記
#pool ntp.ubuntu.com        iburst maxsources 4
#pool 0.ubuntu.pool.ntp.org iburst maxsources 1
#pool 1.ubuntu.pool.ntp.org iburst maxsources 1
#pool 2.ubuntu.pool.ntp.org iburst maxsources 2
pool ntp.nict.jp iburst 

# 最終行に追記 (時刻同期を許可する範囲)
allow 10.0.0.0/24

root@ntp:~# systemctl restart chrony

root@ntp:~# chronyc sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^+ ntp-a2.nict.go.jp             1   6    17    10   -106us[ -122us] +/- 5230us
^- ntp-b3.nict.go.jp             1   6    17     9    +61us[  +61us] +/- 5121us
^+ ntp-b2.nict.go.jp             1   6    17    10  -1103ns[  -17us] +/- 5204us
^* ntp-k1.nict.jp                1   6    17    10    +47us[  +30us] +/- 4669us

root@ntp:~# systemctl status systemd-timesyncd
* systemd-timesyncd.service
     Loaded: masked (Reason: Unit systemd-timesyncd.service is masked.)
     Active: inactive (dead)
  Condition: start condition failed at Wed 2022-11-02 11:08:14 UTC; 39min ago

Nov 02 11:08:14 ntp systemd[1]: Condition check resulted in Network Time Synchronization being skipped.

root@ntp:~# systemctl start
Too few arguments.

root@ntp:~# systemctl status systemd-timesyncd
* systemd-timesyncd.service
     Loaded: masked (Reason: Unit systemd-timesyncd.service is masked.)
     Active: inactive (dead)
  Condition: start condition failed at Wed 2022-11-02 11:08:14 UTC; 39min ago

Nov 02 11:08:14 ntp systemd[1]: Condition check resulted in Network Time Synchronization being skipped.

sudo apt install systemd-timesyncd
timedatectl set-ntp true
sudo systemctl restart systemd-timesyncd.service

sudo apt update
sudo apt upgrade

sudo timedatectl set-timezone Asia/Tokyo

root@ntp:~# date
Wed Nov  2 21:30:27 JST 2022

apt install chrony
apt update
apt upgrade
apt install vim

vim /etc/chrony/chrony.conf

# Welcome to the chrony configuration file. See chrony.conf(5) for more
# information about usable directives.

# Include configuration files found in /etc/chrony/conf.d.
confdir /etc/chrony/conf.d

# Use Debian vendor zone.
pool 172.16.12.220 iburst

# Use time sources from DHCP.
sourcedir /run/chrony-dhcp

# Use NTP sources found in /etc/chrony/sources.d.
sourcedir /etc/chrony/sources.d

# This directive specify the location of the file containing ID/key pairs for
# NTP authentication.
keyfile /etc/chrony/chrony.keys

# This directive specify the file into which chronyd will store the rate
# information.
driftfile /var/lib/chrony/chrony.drift

# Save NTS keys and cookies.
ntsdumpdir /var/lib/chrony

# Uncomment the following line to turn logging on.
#log tracking measurements statistics

# Log files location.
logdir /var/log/chrony

# Stop bad estimates upsetting machine clock.
maxupdateskew 100.0

# This directive enables kernel synchronisation (every 11 minutes) of the
# real-time clock. Note that it can’t be used along with the 'rtcfile' directive.
rtcsync

# Step the system clock instead of slewing it if the adjustment is larger than
# one second, but only in the first three clock updates.
makestep 1 3

# Get TAI-UTC offset and leap seconds from the system tz database.
# This directive must be commented out when using time sources serving
# leap-smeared time.
leapsectz right/UTC

root@mildseven:~# systemctl restart chrony

root@mildseven:~# chronyc sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^* 172.16.12.220                 2   6    17     4  -3837ns[  -36us] +/- 4729us