NTP Time Server Installation Study Notes

NTP Time Server Installation Study Notes-Linux Enterprise Application-Linux server application information, the following is a detailed description. Over time, computer clock tends to drift. Network Time Protocol (NTP) is a way to ensure that your clock remains accurate. NTP is installed by default.

Use the following command to view

[Root @ wap etc] # rpm-qa | grep ntp

Ntp-4.2.0.a.20040617-4.EL4.1

NTP service, mainly including four files

/Etc/ntp. conf; the main configuration file of the NTP service.

/Usr/share/zoneinfo; specifies the time setting files for each major time zone, such as Shanghai/usr/share/zoneinfo/Asia/Shanghai

/Etc/sysconfig/clock; Linux's main Time Zone setting file. After each startup, the Linux operating system reads this file to set the system's preset display time, for example, "Zone = Asia/Shanghai

/Etc/localtim; specifies the time setting file of the local system.

/Bin/date the date and time modification and output commands in Linux

The BIOS time of the/sbin/hwclock host is separated from the Linux system time after the date command is adjusted, it only affects the system time. If you want to change the BIOS time, run the hwlock command.

/Usr/sbin/ntpd; NTP service daemon

/Usr/sbin/ntpdata; the NTP client is used to connect to the NTP server command file.

/Usr/sbin/ntpq Standard Network Time Protocol (NTP) query Program

Configuration

[Root @ wap etc] # vi/etc/ntp. conf

Restrict default ignore

// Ignore all ntp required packets

Restrict 127.0.0.1

Restrict 218.0.0.0 mask has been modified 248 nomodify

Restrict 202. 0.0.0 mask 255.255.255.0 nomodify

Restrict 61. 0.0.0 mask 255.255.255.0 nomodify

// Restrict can be used to restrict subnets and ip addresses. The nomodify parameter indicates that the client can pass server verification, but cannot change server parameters.

Server 0.pool.ntp.org

Server 1.pool.ntp.org

Server 2.pool.ntp.org

// Note: the server option specifies which server to use and each server has an independent row. If prefer parameter is specified on a server

Restrict 0.pool.ntp.org

Restrict 1.pool.ntp.org

Restrict 2.pool.ntp.org

// If restric is not followed by a parameter, all permissions are allowed.

Server 127.127.1.0 # local clock

Fudge 127.127.1.0 stratum 10

Driftfile/var/lib/ntp/drift

// The driftfile option specifies the file used to save the system clock frequency deviation. The ntpd program uses it to automatically compensate for the natural drift of the clock, so that the clock can maintain a considerable accuracy even when the external source is cut off.

Broadcastdelay 0.008

Logfile/var/log/ntp. log

Keys/etc/ntp/keys

Client settings:

Set by crontab timer, run once every 5 minutes

*/5 */usr/local/wapsh/ntprsync. sh

[Root @ AppServer wapsh] # cat ntprsync. sh

#! /Bin/sh

/Usr/sbin/ntpdate 218.0.0.1

/Sbin/hwclock? W

Here, 218.0.0.1 is the Server ip address, so that the client Synchronizes time with the server every five minutes.