linux 中ntp的配置

 安装软件包：

Yum install ntp

Ntp的配置文件是/etc/ntp.conf，工作目录是/etc/ntp/,接着编辑/etc/ntp.conf文件。

2.       服务端配置：

IP:192.168.1.110

编辑/etc/ntp.conf文件：

[root@rhel5 ~]# cat /etc/ntp.conf

# 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

 

# Hosts on local network are less restricted.

restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap(允许内网通讯)

restrict 0.0.0.0 mask 0.0.0.0 nomodify notrap noquery notrust(禁止其他ip来更新时间)

 

# Use public servers from the pool.ntp.org project.

# Please consider joining the pool (http://www.pool.ntp.org/join.html).

server 0.pool.ntp.org(redhat默认情况下是server 0.redhat.pool.ntp.org)

server 1.pool.ntp.org(redhat默认情况下是server 1.redhat.pool.ntp.org)

server 2.pool.ntp.org(redhat默认情况下是server 2.redhat.pool.ntp.org)

#broadcast 192.168.1.255 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

 

# 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 (driftfile 选项，则指定了用来保存系统时钟频率偏差的文件， ntpd程序使用它来自动地补偿时钟的自然漂移， 从而使时钟即使在切断了外来时源的情况下，仍能保持相当的准确度)

 

# 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

Logfile /var/log/ntp.log(定义日志信息)

# Specify the key identifier to use with the ntpq utility.

#controlkey 8

restrict 0. pool.ntp.org mask 255.255.255.255 nomodify notrap noquery

restrict 1. pool.ntp.org mask 255.255.255.255 nomodify notrap noquery

restrict 1. pool.ntp.org mask 255.255.255.255 nomodify notrap noquery

如果restric 后面不带参数，表示可以允许全部权限.以上三个影响/etc/ntp/ step-tickers这个文件，它会随着/etc/ntp.conf文件的变化而变化。

/etc/sysconfig/clock是用来设置时区的文件，例如：

[root@rhel5 ntp]# cat /etc/sysconfig/clock

# The ZONE parameter is only evaluated by system-config-date.

# The timezone of the system is defined by the contents of /etc/localtime.

ZONE="Asia/Chongqing"

UTC=true

ARC=false

/usr/share/zoneinfo这个目录里规定了各主要时区的时间设定文件，例如重庆：/usr/share/zoneinfo/Asia/Chongqing

如果想把同步好的时间写入BIOS里，就要设置/etc/sysconfig/ntp文件，将其中的SYNC_HWCLOCK=no更改为SYNC_HWCLOCK=yes。

启动ntp服务：

[root@rhel5 ntp]# service ntpd restart

Shutting down ntpd: [  OK  ]

ntpd: Synchronizing with time server: [  OK  ]

Starting ntpd: [  OK  ]

[root@rhel5 ntp]#chkconfig ntpd on

3.       客户端的设置：

可以通过使用system-config-time来设置，将其中的时间服务器更改为192.168.1.110即可，或者使用ntpdate  -u 192.168.1.110来和时间服务器同步。切记更改完以后要重新启动NTP服务，使其生效。或者使用crontab  -e来编辑：

*/5 * * * * /usr/sbin/ntpdate  -u 192.168.1.110 表示每五分钟同步一次。重启crond服务即可。

可以使用ntpq –p查看同步状态