我們都知道樹莓派的小巧和省電節省空間等太多的優勢，這里就不一一列舉了，那么樹莓派就需要長時間的運行，可以7×24的方式運行，那么我們就把樹莓派當作一個小的服務器來運行，可以跑一些小的應用，例如可以在局域網中當作NTP服務器，哈哈，這個想法不錯！
初步設想：
1）樹莓派連接網絡之后，時間通過網絡自動同步，那么樹莓派本身的時間就正常了。（不會的自己上網查，類似的文章一堆，不是本文重點）
2）在內部局域網中的其他計算機（包含win，Linux，mac等）都可以以樹莓派作為ntp服務器進行時間同步了。
一、配置局域網NTP服務器
1.安裝ntp服務
通過如下命令安裝ntp服務
sudo apt-get install ntp
2.修改配置文件ntp.conf
安裝完成后，打開/etc/ntp.conf文件，在命令處輸入：
cd / cd etc/ sudo nano ntp.conf
顯示內容如下：
# /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
以上是安裝ntp服務完成后的默認配置。
我自己參考了網上其他人的配置參數，修改成了如下的樣子，參考文章在最后給出了地址：
# /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
根據自己的網絡情況，以及使用情況，請自行修改ntp配置，本文章末尾處給出了配置的參考連接。
3.重啟NTP服務
使用命令重啟ntp服務：sudo service ntp restart
4.本地測試
1）先確認ntp是否已啟動，命令：ps -ef | grep ntp，應該可以看到兩行內容（如果一行太長顯示不完，會顯示成兩行，注意分辨！）
2）命令行輸入：ntpq -p
結果如下，說明NTP服務器進程存在
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
重啟系統
重啟命令：reboot
5.在其它PC同步樹莓派上的時間
在其它PC端填入我的樹莓派IP。
在Windows下即設置時間時選擇Internet時間，並填入樹莓派的IP。
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參考：
https://blog.csdn.net/rk2900/article/details/8658110
https://www.linuxidc.com/Linux/2016-10/135945.htm
https://blog.csdn.net/gsls200808/article/details/51057359
https://www.cnblogs.com/quchunhui/p/7658853.html
https://blog.csdn.net/yjgithub/article/details/54613172
https://www.cnblogs.com/rongpmcu/p/7662141.html