[CentOS] NTP 서버 설정

NTP 서버 설정

>ntp 서버 : 192.168.0.10

>client 서버 : 192.168.0.25

[Server 설정]

1. ntp 설치

[root@localhost ~]# yum install ntp

Loaded plugins: dellsysid, fastestmirror

Loading mirror speeds from cached hostfile

 * base: centos.tt.co.kr

 * extras: centos.tt.co.kr

 * updates: centos.tt.co.kr

base                                                                 | 2.1 kB     00:00     

dell-omsa-indep                                                      | 1.9 kB     00:00     

dell-omsa-specific                                                   | 1.9 kB     00:00     

extras                                                               | 2.1 kB     00:00     

updates                                                              | 1.9 kB     00:00     

updates/primary_db                                                   | 588 kB     00:00     

Setting up Install Process

Resolving Dependencies

--> Running transaction check

---> Package ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1 set to be updated

--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================

 Package        Arch              Version                             Repository       Size

============================================================================================

Installing:

 ntp            x86_64            4.2.2p1-9.el5.centos.2.1            base            1.3 M

Transaction Summary

============================================================================================

Install       1 Package(s)

Upgrade       0 Package(s)

Total download size: 1.3 M

Is this ok [y/N]: y

Downloading Packages:

ntp-4.2.2p1-9.el5.centos.2.1.x86_64.rpm                              | 1.3 MB     00:00     

Running rpm_check_debug

Running Transaction Test

Finished Transaction Test

Transaction Test Succeeded

Running Transaction

  Installing     : ntp                                                                  1/1 

Installed:

  ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1                                                     

Complete!

2. ntp.conf 환경설정

[root@localhost ~]# vi /etc/ntp.conf 

# Permit time synchronization with our time source, but do not

# permit the source to query or modify the service on this system.

restrict default kod nomodify notrap nopeer noquery

restrict -6 default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could

# be tightened as well, but to do so would effect some of

# the administrative functions.

restrict 127.0.0.1

restrict -6 ::1

# Hosts on local network are less restricted.

restrict 192.168.0.0 mask 255.255.255.0 nomodify notrap      <= 주석 제거

# Use public servers from the pool.ntp.org project.

# Please consider joining the pool (http://www.pool.ntp.org/join.html).

#server 0.centos.pool.ntp.org    <= 주석처리

#server 1.centos.pool.ntp.org    <= 주석처리

#server 2.centos.pool.ntp.org    <= 주석처리

server kr.pool.ntp.org             <= 추가

server ntp.postech.ac.kr         <= 추가

#broadcast 192.168.1.255 key 42         # broadcast server

#broadcastclient                        # broadcast client

#broadcast 224.0.1.1 key 42             # multicast server

#multicastclient 224.0.1.1              # multicast client

#manycastserver 239.255.254.254         # manycast server

#manycastclient 239.255.254.254 key 42  # manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup

# and when no outside source of synchronized time is available.

server  127.127.1.0     # local clock

fudge   127.127.1.0 stratum 10

# Drift file.  Put this in a directory which the daemon can write to.

# No symbolic links allowed, either, since the daemon updates the file

# by creating a temporary in the same directory and then rename()'ing

# it to the file.

driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating

# with symmetric key cryptography.

keys /etc/ntp/keys

# Specify the key identifiers which are trusted.

#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.

#requestkey 8

# Specify the key identifier to use with the ntpq utility.

#controlkey 8

3. 서비스 시작

[root@localhost ~]# service ntpd start

Starting ntpd: [  OK  ]

4. ntpd 프로세스 확인

[root@localhost ~]# ps -ef|grep ntp

ntp       4443     1  0 15:15 ?        00:00:00 ntpd -u ntp:ntp -p /var/run/ntpd.pid -g

root      4448  4329  0 15:15 pts/0    00:00:00 grep ntp

5. 부팅 시 ntpd 데몬이 실행되도록 설정

[root@localhost ~]# chkconfig ntpd on

6. 시간 동기화 확인

[root@localhost ~]# ntpq -p

     remote           refid      st t when poll reach   delay   offset  jitter

==============================================================================

*ntp.postech.ac. .GPS.            1 u   22   64   37    8.006   -1.552  10.856

+mail.funix.net  211.115.194.21   3 u   19   64   37    2.744   -1.836   1.333

 LOCAL(0)        .LOCL.          10 l   17   64   37    0.000    0.000   0.001

* : 현재 sync 를 받고 있음을 의미

+ : ntp 접속은 가능, sync는 하지 않음

- : ntp 접속은 가능, sync 가능 리스트에서 제외 된 경우

blank 또는 INIT : 접속이 불가능 함

[Clinet 설정]

1. Client에서 수동으로 시간 동기화

[root@client ~]# yum install ntp

[root@client ~]# ntpdate 192.168.0.10

 8 Jun 16:01:28 ntpdate[3692]: adjust time server 192.168.0.11 offset -0.006139 sec

** 참조 : http://www.pool.ntp.org/ko/use.html

          http://www.pool.ntp.org/zone/asia