1. NTPサーバーの構築
ntp.confを編集する
$ sudo nano /etc/ntp.conf
poolとrestrictの行を追加
ntp.conf
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
driftfile /var/lib/ntp/ntp.drift
# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example
# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
# pick a different set every time it starts up. Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
-server 0.debian.pool.ntp.org iburst
-server 1.debian.pool.ntp.org iburst
-server 2.debian.pool.ntp.org iburst
-server 3.debian.pool.ntp.org iburst
+#server 0.debian.pool.ntp.org iburst
+#server 1.debian.pool.ntp.org iburst
+#server 2.debian.pool.ntp.org iburst
+#server 3.debian.pool.ntp.org iburst
+pool ntp.nict.jp iburst
# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details. The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.
# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery
# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1
# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust
+restrict 8.8.1.0 mask 255.255.255.0
+restrict 8.8.2.0 mask 255.255.255.0
+restrict 192.168.11.0 mask 255.255.255.0
# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255
# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines. Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient
ntpデーモンを再起動する
$ sudo systemctl restart ntp
$ sudo systemctl enable ntp
[option] 2. NTPサーバーの動作確認
別raspiで、NTPサーバーから時刻取得を試みる
別raspi
# ntpdateのインストール（ntpサーバーに時刻を問合せるunixコマンド）
$ sudo apt-get install ntpdate
$ sudo service stop ntp
$ sudo ntpdate <ntp-server-address>
9 Aug 10:53:12 ntpdate[1628]: adjust time server <ntp-server-address> offset 0.004484 se