內網搭建ntp時間同步服務器
在公司內網，搭建服務器集羣時，爲了到達一致性，需要對服務器時間進行同步。內網一般不能訪問互聯網，此時急需一臺內部的時間服務器，用於內網機器的時間同步。
環境：
操作系統：Centos6.6
ntpd服務器：192.168.113.159
客戶端服務器：192.168.113.183
1. 安裝ntpd(ntpd服務器)
[root@localhost ~]# yum install ntpd -y
2. 修改配置文件
[root@localhost ~]# vim /etc/ntp.conf
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).
driftfile /var/lib/ntp/drift
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
# 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
restrict -6 ::1
# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
#允許設置的可信任地址段對NTPD各服務的訪問，但不允許此地址段內客戶端修改NTPD服務器時間（nomodify）
restrict 192.168.113.0 mask 255.255.255.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#註釋掉網絡服務器
#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
#設置本地時間服務器
service 192.168.113.159
# 外部時間服務器不可用時，以本地時間作爲時間服務
server 127.127.1.0
fudge 127.127.1.0 stratum 5
#broadcast 192.168.1.255 autokey # broadcast server
#broadcastclient # broadcast client
#broadcast 224.0.1.1 autokey # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 autokey # manycast client
# Enable public key cryptography.
#crypto
includefile /etc/ntp/crypto/pw
# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys
# Specify the key identifiers which are trusted.
#trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
#requestkey 8
# Specify the key identifier to use with the ntpq utility.
#controlkey 8
# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats
3. 啓動服務，設置開機自啓動
[root@localhost ~]# chkconfig --level 345 ntpd on
[root@localhost ~]# service ntpd restart
關閉 ntpd： [確定]
正在啓動 ntpd： [確定]
4. 客戶端測試
template:/root>/usr/sbin/ntpdate 192.168.113.159
28 Feb 02:44:50 ntpdate[5235]: step time server 192.168.113.159 offset -52476.869449 sec
5. 客戶端配置定時任務
[root@ansible named]#vim /usr/bin/ntpsync.sh
#!/bin/bash
/usr/sbin/ntpdate 192.168.113.159
#同步系統時間到硬件時間
/sbin/hwclock –w
[root@ansible named]#crontab -e
#sync time with ntpserver at 12:00
0 12 * * * /usr/bin/ntpsync.sh