A, ntp server set up
1.centos7.6 build ntp server
Pre-installation:
[root@ntpserver ~]# more /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
[root@ntp-server ~]# ps -ef|grep ntp
root 18054 17742 0 15:53 pts/0 00:00:00 grep --color=auto ntp
[root@ntp-server ~]# ll /etc/|grep ntp
[root@ntp-server ~]# ntpdate
-bash: ntpdate: 未找到命令
[root@ntp-server ~]# systemctl status ntpd
Unit ntpd.service could not be found.
ntp server ip is 172.27.9.131, operating system version centos 7.6, no ntp service prior to installation, the / etc directory and no ntp-related documents, nor ntpdate command
installation:
[root@ntp-server ~]# yum -y install ntp
[root@ntp-server ~]# ps -ef|grep ntp
root 18225 17742 0 16:00 pts/0 00:00:00 grep --color=auto ntp
[root@ntp-server ~]# ll /etc/|grep ntp
drwxr-xr-x 3 root root 52 11月 5 15:59 ntp
-rw-r--r-- 1 root root 2000 8月 6 21:44 ntp.conf
[root@ntp-server ~]# ntpdate
5 Nov 16:01:04 ntpdate[18240]: no servers can be used, exiting
[root@ntp-server ~]# systemctl status ntpd
● ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; disabled; vendor preset: disabled)
Active: inactive (dead)
2.ntp server configuration
New profile ntp-source.conf
[root@ntp-server ~]# cat >/etc/ntp/ntp-source.conf <<EOF
server ntp.ntsc.ac.cn prefer
server ntp1.aliyun.com iburst
server time1.cloud.tencent.com iburst
server 0.cn.pool.ntp.org iburst
server 1.cn.pool.ntp.org iburst
server 2.cn.pool.ntp.org iburst
> EOF
ntp.ntsc.ac.cn for the National Time Service Center domain (the preferred ntp source), ntp1.aliyun.com Ali cloud ntp server, time1.cloud.tencent.com Tencent cloud ntp server, 0.cn.pool. ntp.org as the official website in China ntp ntp server.
Modify the configuration file ntp.conf
#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
includefile /etc/ntp/ntp-source.conf
Clock source configuration file /etc/ntp/ntp-source.conf call
Start Service
[root@ntp-server ~]# systemctl start ntpd
[root@ntp-server ~]# systemctl enable ntpd
Created symlink from /etc/systemd/system/multi-user.target.wants/ntpd.service to /usr/lib/systemd/system/ntpd.service.
[root@ntp-server ~]# systemctl is-enabled chronyd.service
enabled
[root@ntp-server ~]# systemctl disable chronyd.service
Removed symlink /etc/systemd/system/multi-user.target.wants/chronyd.service.
Start ntp service and set the boot, if chrony is set to boot is removed, Centos7 chrony to use the default time synchronization, and ntpd chrony conflict may cause ntpd open failed to start
View ntp service
[root@ntpserver ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*114.118.7.161 123.139.33.3 2 u 36 64 77 23.196 6.770 1.028
+120.25.115.20 10.137.53.7 2 u 24 64 77 20.913 6.897 1.506
-139.199.215.251 100.122.36.196 2 u 22 64 77 21.854 8.122 1.458
-119.28.183.184 100.122.36.196 2 u 19 64 77 33.594 4.266 2.011
+ntp6.flashdance 194.58.202.148 2 u 91 64 72 268.044 6.483 1.516
+119.28.206.193 100.122.36.4 2 u 20 64 77 32.332 7.080 1.344
[root@ntpserver ~]# ntpstat
synchronised to NTP server (114.118.7.161) at stratum 3
time correct to within 996 ms
polling server every 64 s
ntpq -p command to view and ntpstat ntp synchronization status, once every 64 seconds synchronization
Detailed ntpq -p
- Remote : the name of the NTP server in response to this request.
- refid : NTP server on an NTP server.
- ST : level remote remote server. Set to Low level server 1--16, in order to mitigate network congestion and load, it is recommended to avoid direct connection to the server 1 level on principle.
- T : U: unicast (Unicast), b: broadcast (Broadcast), l: local (local clock)
- when the current number of seconds since the last successful request:
- poll : local and remote server synchronization once how much time (in seconds). When the initial run NTP, poll the value will be relatively small, and increase the frequency synchronization server, it is recommended to adjust to the correct time as soon as possible. After the adjustment, poll will gradually increase the value, the frequency of the synchronization will be reduced accordingly.
- the REACH : octal value, and to test whether the server connection. Each time a successful connection, will increase the value of reach.
- Delay : synchronization requires round trip time from the NTP server to send the local machine.
- offset : host through NTP time synchronization with the synchronized time source offset in milliseconds (ms). offset closer to 0, the host and the time of the NTP server closer.
- the Jitter : used to make the value of statistics. Statistical continuous connection in the distribution of the number of offset in particular. I.e., the absolute value of the jitter value is smaller, the precise time of the host.
remote state logo Detailed
- Empty : Indicates that no host for remote communication
- the X- : no longer in use
- - : no longer in use
- # : Good remote node or server but not in use
- + : Good and priority use of the remote node or server
- *****: The current primary synchronization objects as a priority remote node or server
- O : the PPS node (node is active when the priority). The actual system synchronization is derived from the second pulse signal (pulse-per-second, PPS ), PPS may be driven by a clock or by a kernel interface
ntp port View
[root@ntpserver ~]# netstat -nupl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
udp 0 0 172.27.9.131:123 0.0.0.0:* 17174/ntpd
udp 0 0 127.0.0.1:123 0.0.0.0:* 17174/ntpd
udp 0 0 0.0.0.0:123 0.0.0.0:* 17174/ntpd
udp6 0 0 fe80::20c:29ff:fed9:123 :::* 17174/ntpd
udp6 0 0 ::1:123 :::* 17174/ntpd
udp6 0 0 :::123 :::* 17174/ntpd
ntp service port 123, UDP protocol
Second, the client synchronization service mode --ntpd
1.centos7.3
Installing and starting with ntp server, configured as follows:
[root@centos7 ~]# view /etc/ntp.conf
#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 ntpserver iburst
[root@centos7 ~]# view /etc/hosts
172.27.9.131 ntpserver
[root@centos7 ~]# systemctl enable ntpd
[root@centos7 ~]# systemctl start ntpd
[root@centos7 ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*ntpserver 114.118.7.161 3 u 1 64 3 0.221 12.641 0.495
[root@centos7 ~]# ntpstat
synchronised to NTP server (172.27.9.131) at stratum 4
time correct to within 1049 ms
polling server every 64 s
2.ubuntu1604
root@ubuntu1604:~# view /etc/hosts
root@ubuntu1604:~# apt install -y ntp
root@ubuntu1604:~# view /etc/ntp.conf
root@ubuntu1604:~# systemctl enable ntp
ntp.service is not a native service, redirecting to systemd-sysv-install
Executing /lib/systemd/systemd-sysv-install enable ntp
root@ubuntu1604:~# systemctl start ntp
root@ubuntu1604:~# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*ntpserver 114.118.7.161 3 u 51 64 377 0.254 -4.194 1.090
3.suse11
Install ntp
suse11:~ # view /etc/hosts
172.27.9.131 ntpserver
suse11:~ # view /etc/ntp.conf
#server 127.127.1.0 # local clock (LCL)
#fudge 127.127.1.0 stratum 10 # LCL is unsynchronized
server ntpserver iburst
suse11:~ # service ntp restart
Shutting down network time protocol daemon (NTPD) done
Starting network time protocol daemon (NTPD) done
suse11:~ # ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*ntpserver 114.118.7.161 3 u 1 64 1 0.223 2.271 0.285
suse11:~ # chkconfig ntp on
suse11:~ # chkconfig --list|grep ntp
ntp 0:off 1:off 2:off 3:on 4:off 5:on 6:off
The default is synchronized with the local, modified to synchronize with ntpserver.
4.AIX
aix:/ #view /etc/ntp.conf
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace
server ntpserver
aix:/ #view /etc/hosts
172.27.9.131 ntpserver
aix:/ #stopsrc -s xntpd
0513-044 The /usr/sbin/xntpd Subsystem was requested to stop.
aix:/ #startsrc -s xntpd
0513-059 The xntpd Subsystem has been started. Subsystem PID is 1663192.
aix:/ #ntpq -p
remote refid st t when poll reach delay offset disp
==============================================================================
*ntpserver 114.118.7.161 3 u 1 64 37 1.16 5.744 875.43
aix:/ #l***c -ls xntpd
Program name: /usr/sbin/xntpd
Version: 3
Leap indicator: 00 (No leap second today.)
Sys peer: ntpserver
Sys stratum: 4
Sys precision: -17
Debug/Tracing: DISABLED
Root distance: 0.051193
Root dispersion: 0.176468
Reference ID: 172.27.9.131
Reference time: e16e4fd5.e2945000 Thu, Nov 7 2019 16:09:57.885
Broadcast delay: 0.003906 (sec)
Auth delay: 0.000122 (sec)
System flags: pll monitor filegen
System uptime: 436 (sec)
Clock stability: 7.000000 (sec)
Clock frequency: 0.000000 (sec)
Peer: ntpserver
flags: (configured)(sys peer)
stratum: 3, version: 3
our mode: client, his mode: server
Subsystem Group PID Status
xntpd tcpip 1663192 active
5.redhat6.8
[root@redhat6 ~]# view /etc/hosts
172.27.9.131 ntpserver
[root@redhat6 ~]# view /etc/ntp.conf
server ntpserver iburst
[root@redhat6 ~]# service ntpd restart
Shutting down ntpd: [ OK ]
Starting ntpd: [ OK ]
[root@redhat6 ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*ntpserver 114.118.7.161 3 u 1 64 1 0.432 3.366 0.000
[root@redhat6 ~]# ntpstat
synchronised to NTP server (172.27.9.131) at stratum 4
time correct to within 8030 ms
polling server every 64 s
6.windows 7
Applicable windows7 and Windows Server 2008, etc.
Third, the client synchronization --ntpdate command mode
[root@centos7 ~]# systemctl stop ntpd
[root@centos7 ~]# ntpdate ntpserver
7 Nov 16:33:02 ntpdate[2618]: adjust time server 172.27.9.131 offset -0.002048 sec
[root@centos7 ~]# crontab -l
0 1 * * * /usr/sbin/ntpdate ntpserver
ntp service and ntpdate command can not be used simultaneously, before using ntpdate, ntp service needs to be stopped. Ntpdate command mode using suitable clock synchronization suse, redhat, AIX, centos, ubuntu other operating systems, the timing task timing synchronization can be made per day.
ntpd ntpdate service mode and command mode can achieve clock synchronization client can choose the best according to production.