在树莓派是安装并配置NTP服务

我们都知道树莓派的小巧和省电节省空间等太多的优势，这里就不一一列举了，那么树莓派就需要长时间的运行，可以7×24的方式运行，那么我们就把树莓派当作一个小的服务器来运行，可以跑一些小的应用，例如可以在局域网中当作NTP服务器，哈哈，这个想法不错！

初步设想：

1）树莓派连接网络之后，时间通过网络自动同步，那么树莓派本身的时间就正常了。（不会的自己上网查，类似的文章一堆，不是本文重点）

2）在内部局域网中的其他计算机（包含win，Linux，mac等）都可以以树莓派作为ntp服务器进行时间同步了。

一、配置局域网NTP服务器

1.安装ntp服务

通过如下命令安装ntp服务
sudo apt-get install ntp

2.修改配置文件ntp.conf

安装完成后，打开/etc/ntp.conf文件，在命令处输入：

cd /
cd etc/
sudo nano ntp.conf

显示内容如下：

# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help

driftfile /var/lib/ntp/ntp.drift


# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable


# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example

# pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your server will
# pick a different set every time it starts up.  Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
server 0.debian.pool.ntp.org iburst
server 1.debian.pool.ntp.org iburst
server 2.debian.pool.ntp.org iburst
server 3.debian.pool.ntp.org iburst


# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust


# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255

# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines.  Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient

以上是安装ntp服务完成后的默认配置。

我自己参考了网上其他人的配置参数，修改成了如下的样子，参考文章在最后给出了地址：

# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help

driftfile /var/lib/ntp/ntp.drift


# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable


# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example

# pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your server will
# pick a different set every time it starts up.  Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
server 0.debian.pool.ntp.org iburst
server 1.debian.pool.ntp.org iburst
server 2.debian.pool.ntp.org iburst
server 3.debian.pool.ntp.org iburst
server time.asia.apple.com prefer
server ntp.sjtu.edu.cn prefer
server 127.127.1.0
fudge 127.127.1.0 stratum 10


# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery
#restrictdefault nomodify


# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust


# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255

# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines.  Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient

根据自己的网络情况，以及使用情况，请自行修改ntp配置，本文章末尾处给出了配置的参考连接。

3.重启NTP服务

使用命令重启ntp服务：sudo service ntp restart

4.本地测试

1）先确认ntp是否已启动，命令：ps -ef | grep ntp，应该可以看到两行内容（如果一行太长显示不完，会显示成两行，注意分辨！）

2）命令行输入：ntpq -p

结果如下，说明NTP服务器进程存在

pi@raspberrypi36:/ $ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+cn.ntp.faelix.n 185.134.196.169  2 u    1   64  377  253.107   -7.402  23.282
+d.hnd.pobot.net 255.254.0.27     2 u   15   64  155  249.128   41.977   8.036
 static-5-103-13 .INIT.          16 u    -   64    0    0.000    0.000   0.000
*time5.aliyun.co 10.137.38.86     2 u    9   64  377   30.167    3.322   3.654