NTPサーバを立ち上げてみる

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NTPサーバを立ち上げてみる
（CentOS3.5）

Modified: 26 July 2005

NTPサーバにする実験 - "/etc/ntp.conf"の設定
ローカルのNTPサーバを利用する実験

NTPサーバにする実験 - "/etc/ntp.conf"の設定

"/etc/ntp.conf"を以下のように設定します。

設定のポイントは、３つです。

このNTPサーバを利用するネットワークを、IPアドレスかネットワークアドレスで指定します。
外部のNTPサーバを、IPアドレスかネットワークアドレスで指定します。
サーバーを指定します。

# Prohibit general access to this service.
restrict default ignore

# 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 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap

# --- 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 210.173.160.27 noquery <==必ずIPアドレス（数字）で指定すること
restrict 210.173.160.57 noquery
restrict 210.173.160.87 noquery

# --- 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
server ntp1.jst.mfeed.ad.jp
server ntp2.jst.mfeed.ad.jp
server ntp3.jst.mfeed.ad.jp

#
# 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 /var/lib/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の起動

以下のコマンドで、NTPDを起動します。

# service ntpd start
ntpdを起動中:                                              [  OK  ]
#

動作確認してみます。動作確認は、"ntpq -p"で行います。

まずは、以下のような状態です。

# ntpq -p
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 ntp1.jst.mfeed. 0.0.0.0         16 u    -   64    0    0.000    0.000 4000.00
 ntp2.jst.mfeed. 0.0.0.0         16 u    -   64    0    0.000    0.000 4000.00
 ntp3.jst.mfeed. 0.0.0.0         16 u    -   64    0    0.000    0.000 4000.00
#

少したって、動作確認を、"ntpq -p"で行うと、以下のようになります。

# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 ntp1.jst.mfeed. ote-ntp1.jpnap.  2 u    1   64    3   11.516   22.100   3.743
 ntp2.jst.mfeed. ote-ntp1.jpnap.  2 u    5   64    3   11.607  -10.373  34.530
 ntp3.jst.mfeed. ote-ntp1.jpnap.  2 u    5   64    3   11.753  -10.820  34.550
#

その後しばらく待った結果、以下のように、左端のカラムに、"*"や"+"がついてくると成功です。

# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+ntp1.jst.mfeed. ote-ntp1.jpnap.  2 u   19   64   77   11.515  -11.271  30.990
+ntp2.jst.mfeed. ote-ntp1.jpnap.  2 u   18   64   77   11.758  -17.889  39.970
*ntp3.jst.mfeed. ote-ntp1.jpnap.  2 u   24   64   77   11.298   10.221  39.151
#

ローカルのNTPサーバを利用する実験　

ローカルのNTPサーバを指定すればOKです。

restrict default ignore
restrict 127.0.0.1 
restrict 192.168.0.0 mask 255.255.255.0 notrust nomodify notrap
restrict 192.168.0.11 noquery
server 192.168.83.11
driftfile /var/lib/ntp/drift
broadcastdelay  0.008
authenticate yes
keys            /etc/ntp/keys

動作確認できました。

# ntpq -p
   remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*192.168.0.11  sagi.cc.tut.ac.  2 u   40   64   77    1.970   12.749   4.837
#

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