LinuxでNTPサーバ





○設定ファイルを編集
/etc/ntp/confを以下のように編集
# Prohibit general access to this service.
#restrict default ignore・・・コメントアウトした(デフォルトでは全NTPアクセスを拒否する。)
# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1


# -- CLIENT NETWORK -------
# Permit systems on this network to synchronize with this
# time service.  Do not permit those systems to modify the
# configuration of this service.  Also, do not use those
# systems as peers for synchronization.
# restrict 192.168.1.0 mask 255.255.255.0 notrust nomodify notrap
restrict 2.2.2.0 mask 255.255.255.0 notrust nomodify notrap・・・NTPアクセスを許可したいネットワークを記述

# --- OUR TIMESERVERS -----
# or remove the default restrict line
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.

# restrict mytrustedtimeserverip mask 255.255.255.255 nomodify notrap noquery
# server mytrustedtimeserverip
restrict 1.1.1.1 nomodify notrap noquery・・・NTPサーバ1.1.1.1にアクセスするため追加
server  1.1.1.1 ・・・NTPサーバ1.1.1.1にアクセスするため追加


# --- NTP MULTICASTCLIENT ---
#multicastclient                        # listen on default 224.0.1.1
# restrict 224.0.1.1 mask 255.255.255.255 notrust nomodify notrap
# restrict 192.168.1.0 mask 255.255.255.0 notrust nomodify notrap



# --- GENERAL CONFIGURATION ---
#
# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available. The
# default stratum is usually 3, but in this case we elect to use stratum
# 0. Since the server line does not have the prefer keyword, this driver
# is never used for synchronization, unless no other other
# synchronization source is available. In case the local host is
# controlled by some external source, such as an external oscillator or
# another protocol, the prefer keyword would cause the local host to
# disregard all other synchronization sources, unless the kernel
# modifications are in use and declare an unsynchronized condition.
#
server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 10

#
# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
#
driftfile /etc/ntp/drift
broadcastdelay  0.008

#
# Authentication delay.  If you use, or plan to use someday, the
# authentication facility you should make the programs in the auth_stuff
# directory and figure out what this number should be on your machine.
#
authenticate yes

#
# Keys file.  If you want to diddle your server at run time, make a
# keys file (mode 600 for sure) and define the key number to be
# used for making requests.
#
# PLEASE DO NOT USE THE DEFAULT VALUES HERE. Pick your own, or remote
# systems might be able to reset your clock at will. Note also that
# ntpd is started with a -A flag, disabling authentication, that
# will have to be removed as well.
#
keys            /etc/ntp/keys

○ntpdを再起動する
# /etc/init.d/ntpd stop
# /etc/init.d/ntpd start

○動作確認
# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*1.1.1.1         3.3.3.3          3 u    6   64  377    0.339   27.499   0.542
 LOCAL(0)        LOCAL(0)        10 l    8   64  377    0.000    0.000   0.008