CentOS ntp 설치

✔️ CentOS 6에서 테스트하였습니다.

ntp 설치

1 설치 확인

설치 안됨

[root@zetawiki ~]# rpm -qa ntp

설치됨

[root@zetawiki ~]# rpm -qa ntp
ntpdate-4.2.4p8-2.el6.centos.x86_64
ntp-4.2.4p8-2.el6.centos.x86_64

2 설치

[root@zetawiki ~]# yum install ntp
... (생략)
=====================================================================================================
 Package             Arch               Version                            Repository           Size
=====================================================================================================
Installing:
 ntp                 x86_64             4.2.6p5-5.el6.centos.4             updates             595 k
Updating for dependencies:
 ntpdate             x86_64             4.2.6p5-5.el6.centos.4             updates              77 k

Transaction Summary
=====================================================================================================
Install       1 Package(s)
Upgrade       1 Package(s)

Total download size: 672 k
Is this ok [y/N]: y

... (생략)
Installed:
  ntp.x86_64 0:4.2.6p5-5.el6.centos.4                                                                

Dependency Updated:
  ntpdate.x86_64 0:4.2.6p5-5.el6.centos.4                                                            

Complete!

3 설치 위치

[root@zetawiki ~]# whereis ntp
ntp: /etc/ntp /etc/ntp.conf
[root@zetawiki ~]# which ntpq
/usr/sbin/ntpq
[root@zetawiki ~]# which ntpdate
/usr/sbin/ntpdate
[root@zetawiki ~]# which ntpd
/usr/sbin/ntpd
[root@zetawiki ~]# service ntpd status
ntpd is stopped

설정파일 ntp.conf는 /etc에 있다.
ntpq, ntpdate, ntpd는 /usr/sbin에 있다.
ntpd는 중지된 상태이다.

4 동기화 서버 설정

공용 ntp 서버 목록 문서를 참고하십시오.

/etc/ntp.conf 문서를 참고하십시오.

chkconfig ntpd on
echo driftfile /var/lib/ntp/drift > /etc/ntp.conf
echo restrict default kod nomodify notrap nopeer noquery >> /etc/ntp.conf
echo restrict -6 default kod nomodify notrap nopeer noquery >> /etc/ntp.conf
echo restrict 127.0.0.1 >> /etc/ntp.conf
echo restrict -6 ::1 >> /etc/ntp.conf
echo server 1.kr.pool.ntp.org >> /etc/ntp.conf
echo server 1.asia.pool.ntp.org >> /etc/ntp.conf
echo server 2.asia.pool.ntp.org >> /etc/ntp.conf
echo includefile /etc/ntp/crypto/pw >> /etc/ntp.conf
echo keys /etc/ntp/keys >> /etc/ntp.conf
service ntpd restart
ntpq -p

5 즉시 동기화

명령어

ntpdate 서버주소

실행 예시

[root@zetawiki ~]# ntpdate time.windows.com

6 차이 보기

명령어

ntpdate -d 서버주소

실행 예시

[root@zetawiki ~]# ntpdate -d time.windows.com
 2 Oct 02:08:06 ntpdate[3166]: ntpdate 4.2.4p8@1.1612-o Tue Nov 29 00:09:13 UTC 2011 (1)
Looking for host time.windows.com and service ntp
host found : wwwco1test13.microsoft.com
transmit(65.55.21.21)
receive(65.55.21.21)
transmit(65.55.21.21)
receive(65.55.21.21)
transmit(65.55.21.21)
receive(65.55.21.21)
transmit(65.55.21.21)
receive(65.55.21.21)
transmit(65.55.21.21)
server 65.55.21.21, port 123
stratum 2, precision -6, leap 00, trust 000
refid [65.55.21.21], delay 0.19615, dispersion 0.00293
transmitted 4, in filter 4
reference time:    d4144c6a.71b59070  Tue, Oct  2 2012  2:07:54.444
originate timestamp: d4144c77.e83cbb72  Tue, Oct  2 2012  2:08:07.907
transmit timestamp:  d4144c77.cca0c88c  Tue, Oct  2 2012  2:08:07.799
filter delay:  0.22122  0.19688  0.19693  0.19615 
         0.00000  0.00000  0.00000  0.00000 
filter offset: 0.010714 0.029665 0.029863 0.030388
         0.000000 0.000000 0.000000 0.000000
delay 0.19615, dispersion 0.00293
offset 0.030388

 2 Oct 02:08:07 ntpdate[3166]: adjust time server 65.55.21.21 offset 0.030388 sec

→ 마지막 offset 값이 양수이면 로컬서버가 늦는 것, 음수이면 로컬서버가 빠른 것.

→ 로컬 서버가 약 0.03초 늦다.

7 같이 보기