ntp.conf详解
linux系统的ntp.conf文件默认保存在/etc/ntp.conf
版本：
[root@dsview ntpstats]# cat /etc/redhat-release
CentOS release 6.5 (Final)
[root@dsview ntpstats]# uname -a
Linux dsview 2.6.32-431.el6.x86_64 #1 SMP Fri Nov 22 03:15:09 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
[root@dsview ntpstats]# ntpd --version
ntpd 4.2.6p5
ntpd 4.2.6p5@1.2349-o Sat Nov 23 18:21:48 UTC 2013 (1)
[root@dsview ntpstats]# 来个例子：直接从服务器上拽出来的
# 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.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
server 192.168.6.200 iburst
server 192.168.6.201 iburst
server 192.168.6.202 iburst
#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
logfile /var/log/ntp.log
#pidfile /var/run/ntpd.pid详细解析：
#将自己主机的bios芯片震荡频率与上层的Time server频率比较，将误差记录在这个文件里，一般保持默认
driftfile /var/lib/ntp/drift
# 作为客户端一般不需要设置，保持默认
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
# 作为客户端一般不需要设置，保持默认
restrict 127.0.0.1
restrict -6 ::1
# 设置访问控制的策略的，作为客户端一般不需要设置，保存默认
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap参考时钟源设置
# 时钟源配置格式：
# [server] address [prefer] [mode int] [minpoll int] [maxpoll int]
# 注释掉默认配置
#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
# 这里需要修改为时间服务器地址，可以添加多个
server 192.168.6.200 iburst
server 192.168.6.201 iburst
server 192.168.6.202 iburst时钟源格式详解，前缀一般默认是server，也可以是其他
| server address | 选取的参考时钟源 |
| peer address | 与本机一起作为共同时钟源对外服务，在服务器启动时初始化，两台服务器会自行协议主备关系 |
| broadcast address | 作为时钟源向指定广播域发送时钟信息 |
| manycastclient address | 接受广播的NTP信息客户端配置 |
时钟源配置选项
| burst | 时钟源可访问时发送8个包，默认发送间隔2秒，只用于server |
| iburst | 时钟源不可访问时发送8个包，默认发送间隔2秒，只用于server |
| minpool/maxpool | 最小/最大轮训间隔，间隔为2的minpool/maxpool次方，取值4-17。只用于peer和server |
| noselect | 指定时钟源不再有效，只用于peer和server |
| perfer | 首选时钟源，只用于peer和server |
| ttl | ....（一般用不上） |
可添加其他配置
# Enable writing of statistics records.
# 记录状态，保存在/var/log/ntpstatus下
statistics clockstats cryptostats loopstats peerstats
# 日志文件保存路径，可按需求添加
logfile /var/log/ntp.log
# 进程ID号保存的文件，可按需求添加
#pidfile /var/run/ntpd.pid后面有新了解再补充
