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CentOS7.3にNTPサーバを立てる

Last updated at Posted at 2018-05-14

概要

・NICTに時刻同期を行い、所定のネットワークにあるマシンからの時刻同期要求を受け付ける

導入・構築

1.NTPDのインストール

[root@servername]# yum -yinstall ntp

2.NTPDの設定編集

①設定ファイルを開く

[root@servername]# vi /etc/ntp.conf

②同期を取るサーバを変更する

ntp.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html)
# server 0.centos.pool.ntp.org iburst
# server 1.centos.pool.ntp.org iburst
# server 2.centos.pool.ntp.org iburst
# server 3.centos.pool.ntp.org iburst
server ntp.nict.jp minpoll 6 maxpoll 10
server ntp1.jst.mfeed.ad.jp minpoll 6 maxpoll 10
server ntp2.jst.mfeed.ad.jp minpoll 6 maxpoll 10

minpoll..最小ポーリング間隔
maxpoll..最大ポーリング間隔
時刻同期が指定のNTPサーバとズレが無くなってきたら、最大ポーリング間隔まで時刻同期のタイミングを遅らせることができる。

③時刻同期を許可するネットワークを定義する

ntp.conf
# Host on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
restrict xxx.xxx.xxx.xxx mask xxx.xxx.xxx.xxx nomodify notrap

3.NTPサービス開始&スタートアップ登録

# サービス開始
[root@servername]# systemctl start ntpd

# OS起動時にサービスを開始する(スタートアップ登録)
[root@servername]# systemctl enable ntpd

4.NTP通信をfirewallに通す

[root@servername]# firewall-cmd --add-service=ntp --permanent
success
[root@servername]# firewall-cmd --reload
success

5.動作確認

[root@servername]# ntpq -p

remote                refid     st t when poll reach  delay  offset  jitter
============================================================================
*ntp-b2.nict.go. .NICT.          1 u   31   64  377   7.641  -20.779  5.652
+ntp1.jst.mfeed. 133.243.236.17  2 u   28   64  377   5.827  -10.895  7.063
+ntp2.jst.mfeed. 133.243.236.17  2 u   21   64  377   6.632  -13.189  4.819

参考

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