1、配置NTP服务端
环境：redhat 6.5
| 服务器主机名 | ip地址 | 说明 |
|---|---|---|
| server | 192.168.57.20 | NTP服务端 |
| client | 192.168.57.21 | NTP客户端 |
搭建说明：
本地server使用外网ntp源同步时间，再作为NTP服务端同步时间给本地client服务器NTP客户端
1.1 安装NTP服务
在ntp服务器查看系统是否安装NTP服务
[root@server~]# rpm -qa|grep ntp ntpdate-4.2.6p5-1.el6.x86_64 fontpackages-filesystem-1.41-1.1.el6.noarch ntp-4.2.6p5-1.el6.x86_64
如果没有安装，安装ntp
yum -y install ntp
备份原有ntp配置文件
mv /etc/ntp.conf /etc/npt.conf.bak
1.2 配置NTP服务端
编辑ntp.conf配置文件
# Permit time synchronization with our time source, but do not # permit the source to query or modify the service on this system. restrict default ignore restrict 127.0.0.1 restrict 192.168.112.0 mask 255.255.255.0 nomodify # 设置容许访问该ntp服务器的网络地址段 restrict 192.168.57.0 mask 255.255.255.0 nomodify # Permit all access over the loopback interface. This could # be tightened as well, but to do so would effect some of # the administrative functions. # Use public servers from the pool.ntp.org project. # Please consider joining the pool (http://www.pool.ntp.org/join.html). # 设定NTP主机来源（其中prefer表示优先主机） #server 1.cn.pool.ntp.org prefer # 默认优先使用1.cn.pool.ntp.org #server 1.rhel.pool.ntp.org server pool.ntp.org #broadcast 172.30.8.255 key 42 # broadcast server #broadcastclient # broadcast client #broadcast 224.0.1.1 key 42 # multicast server #multicastclient 224.0.1.1 # multicast client #manycastserver 239.255.254.254 # manycast server #manycastclient 239.255.254.254 key 42 # manycast client # Undisciplined Local Clock. This is a fake driver intended for backup # and when no outside source of synchronized time is available. server 127.127.1.0 fudge 127.127.1.0 stratum 10 # local clock设置本地ntp服务器地址，当外网ntp服务器连接异常时，使用本地NTP服务器进行同步 # 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 # Key file containing the keys and key identifiers used when operating # with symmetric key cryptography. broadcastdelay 0.008 logfile /var/log/ntp.log 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
启动ntp服务
service ntpd start
设置开机启动
chkconfig ntpd on
查看NTP状态
-bash-4.1$ ntpstat
synchronised to local net at stratum 11
time correct to within 12 ms
polling server every 64 s
-bash-4.1$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*LOCAL(0) .LOCL. 10 l 11 64 377 0.000 0.000 0.000
120.25.115.20 .INIT. 16 u - 1024 0 0.000 0.000 0.000
2 配置NTP客户端
2.1 安装NTP服务
在ntp服务器查看系统是否安装NTP服务
[root@client~]# rpm -qa|grep ntp ntpdate-4.2.6p5-1.el6.x86_64 fontpackages-filesystem-1.41-1.1.el6.noarch ntp-4.2.6p5-1.el6.x86_64
如果没有安装，安装ntp
yum -y install ntp
备份原有ntp配置文件
mv /etc/ntp.conf /etc/npt.conf.bak
2.2 配置NTP服务端
修改/etc/ntp.conf文件
# 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 # Use public servers from the pool.ntp.org project. # Please consider joining the pool (http://www.pool.ntp.org/join.html). # server 0.rhel.pool.ntp.org iburst # server 1.rhel.pool.ntp.org iburst # server 2.rhel.pool.ntp.org iburst server 192.68.57.20 perfer # 设置192.168.57.20为优先的ntp服务器 restrict 192.68.57.20 nomodify notrap noquery server 127.127.1.0 # local clock fudge 127.127.1.0 stratum 10 #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
启动NTP服务
service ntpd start
设置NTP服务自启动
chkconfig ntpd on
查看ntp服务状态：
-bash-4.1$ ntpstat
synchronised to NTP server (192.168.57.20) at stratum 12
time correct to within 21 ms
polling server every 256 s
-bash-4.1$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*192.168.57.20 LOCAL(0) 11 u 242 256 377 0.302 0.012 0.187
LOCAL(0) .LOCL. 10 l 46m 64 0 0.000 0.000 0.000
3、常见错误
3.1 ntpq -p查看时间同步情况时报localhost: timed out, nothing received错误
在使用ntpq -p时报：
localhost: timed out, nothing received ***Request timed out
解决办法:
1、查看/etc/hosts文件，确认有以下信息，可以正确解析本地ntp服务
127.0.0.1 localhost localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
2、如果/etc/hosts文件配置正确，使用ntpq -4p（即指定通过ipv4 地址获取返回值），如果正常显示，但是使用ntpq -6p(即指定通过ipv4 地址获取返回值)异常，则说明时因为开启了Ipv6 ，默认ntpq 先走Ipv6的通道，而ECS linux 默认无法直接访问ipv6地址，因此会访问超时
可以禁用接口的IPv6，然后就会正确，方法如下：
/etc/sysctl.conf 文件尾添加如下参数
# 禁用整个系统所有接口的IPv6 net.ipv6.conf.all.disable_ipv6 = 1 # 禁用某一个指定接口的IPv6(例如：eth0, eth1) net.ipv6.conf.eth1.disable_ipv6 = 1 net.ipv6.conf.eth0.disable_ipv6 = 1
然后重启网络服务
service restart network
然后使用ntpq -p,返回值就正常
3.2 ntpq -p查看时间同步情况时报no association ID's returned错误信息
解决方法：
1、关闭selinux
-bash-4.1$ vi /etc/selinux/config # This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. #SELINUX=enforcing SELINUX=disabled # 设置为disabled # SELINUXTYPE= can take one of these two values: # targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted
2、执行restorecon -R -v /etc/ntp.conf
3、重启ntp服务
service ntpd restart
3.3 添加ntp服务开机自启动，报：service nptd does not support chkconfig
解决方法：
1、查看ntpd服务脚本，是不是在/etc/init.d/目录下
-bash-4.1$ ll /etc/init.d/ntpd -rwxr-xr-x 1 root root 1974 10月 30 20:28 /etc/init.d/ntpd
注：一般成功安装ntp以后都会有
2、在chkconfig工具服务列表中增加ntpd服务，此时服务会被在/etc/rc.d/rcN.d中赋予K/S入口了
chkconfig --add ntpd
3、修改/etc/init.d/ntpd
vi打开/etc/init.d/ntpd文件
在
#!/bin/bash
后加入
# chkconfig: 2345 10 90# description: myservice
4、设置ntp服务自启动,发现正常
chkconfig ntpd on