定時任務 chrony sage -i ins messages acc dea 任務

時間服務器
NTP（Network Time Protocol，網絡時間協議）是用來使網絡中的各個計算機時間同步的一種協議。
NTP服務器就是利用NTP協議提供時間同步服務的。

ntp軟件（支持ntp協議） CentOS6自帶
CentOS7需要安裝的

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chrony軟件（支持ntp協議） CentOS7自帶

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環境準備
[root@Cobbler ~]# getenforce
Disabled
[root@Cobbler ~]# systemctl status firewalld.service
● firewalld.service - firewalld - dynamic firewall daemon

Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
Active: inactive (dead)
Docs: man:firewalld(1)
[root@m02 ~]# hostname -I
10.0.0.62 172.16.1.62

第一種方法：NTP

服務端部署

1. 下載軟件
   [root@m02 ~]# yum install -y ntp
   [root@m02 ~]# rpm -qa ntp
   ntp-4.2.6p5-25.el7.centos.2.x86_64

2. 配置ntp文件
   備份
   [root@m02 ~]# cp /etc/ntp.conf{,.ori}
   
   修改
   [root@m02 ~]# vim /etc/ntp.conf

8 #restrict default nomodify notrap nopeer noquery
9 restrict default nomodify

21 #server 0.centos.pool.ntp.org iburst
22 #server 1.centos.pool.ntp.org iburst
23 #server 2.centos.pool.ntp.org iburst
24 #server 3.centos.pool.ntp.org iburst
25 server ntp1.aliyun.com

3. 與備份文件對比
   [root@m02 ~]# diff /etc/ntp.conf{,.ori}
   
   8,9c8,9
   < #restrict default nomodify notrap nopeer noquery
   < restrict default nomodify

restrict default nomodify notrap nopeer noquery

21,25c21,25
< #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 ntp1.aliyun.com

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

4. 啟動服務

[root@m02 ~]# systemctl start ntpd

5. 檢查ntp是否能同步
   [root@m02 ~]# ntpq -p
   remote refid st t when poll reach delay offset jitter

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time5.aliyun.co 10.137.38.86 2 u 36 64 1 52.686 -1371.9 0.000

[root@m02 ~]# ntpstat
synchronised to NTP server (182.92.12.11) at stratum 3
time correct to within 982 ms
polling server every 64 s

客戶端部署

1. 下載軟件
   [root@Cobbler ~]# yum -y install ntpdate

2. 測試是否同步
   [root@Cobbler ~]# ntpdate 172.16.1.62
   10 Jan 09:07:47 ntpdate[1504]: adjust time server 172.16.1.62 offset -0.001513 sec

3. 定時任務

[root@Cobbler ~]# crontab -l
#時間同步
/5 * /usr/sbin/ntpdate 172.16.1.62 &>/dev/null

第二種方法：chrony

服務端部署

1. 修改chrony配置文件
   [root@m02 ~]# vim /etc/chrony.conf
   1 # Use public servers from the pool.ntp.org project.
   2 # Please consider joining the pool
   (http://www.pool.ntp.org/join.html).
   3 #server 0.centos.pool.ntp.org iburst
   4 #server 1.centos.pool.ntp.org iburst
   5 #server 2.centos.pool.ntp.org iburst
   6 #server 3.centos.pool.ntp.org iburst
   7 server ntp1.aliyun.com

   26 # Allow NTP client access from local network.
   27 #allow 192.168.0.0/16
   28 allow 172.16.1.0/24

2. 開啟服務
   [root@m02 ~]# systemctl start chronyd
   客戶端部署
3. 修改配置文件
   [root@Cobbler ~]# vim /etc/chrony.conf

1 # Use public servers from the pool.ntp.org project.
2 # Please consider joining the pool (http://www.pool.ntp.org/join.html).
3 #server 0.centos.pool.ntp.org iburst
4 #server 1.centos.pool.ntp.org iburst
5 #server 2.centos.pool.ntp.org iburst
6 #server 3.centos.pool.ntp.org iburst
7 server 172.16.1.62

2. 開啟服務
   [root@Cobbler ~]# systemctl start chronyd

3. 修改時間測試
   [root@Cobbler ~]# date -s 1111
   Wed Jan 10 11:11:00 CST 2018

4. 查看日誌
   [root@Cobbler ~]# tailf /var/log/messages
   Jan 10 09:30:26 Cobbler chronyd[1593]: Selected source 172.16.1.62
   Jan 10 09:30:26 Cobbler chronyd[1593]: System clock wrong by -6348.794966 seconds, adjustment started
   Jan 10 09:30:26 Cob[root@Cobbler ~]# date -s 1111
   Wed Jan 10 11:11:00 CST 2018

5.查看時間
[root@Cobbler ~]# date
Wed Jan 10 11:15:47 CST 2018
[root@Cobbler ~]# date
Wed Jan 10 09:30:37 CST 2018

CentOS7之NTP服務器簡單配置