[Linux CentOS 7 ] NTP 설정 방법

NTP 설정 매뉴얼 ( CentOS Linux release 7.9 )

 

NTP 서비스 활성화 여부 확인 방법

- systemctl status ntpd.service

- 현재 서버에 NTP 서비스가 활성화되어 있는지 확인할 수 있다

[root@localhost ~]# systemctl status ntpd.service
● ntpd.service - Network Time Service
   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)
   Active: inactive (dead)

 

NTP 서비스 Config 설정 방법

-  /etc/ntp.conf  파일 확인

- 사용할 NTP 서버 추가

- 인터넷 검색하니 대부분 time.bora.net / time.konet.net 서버를 등록해서 사용하고 있어 두 개 주소 추가

# 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 iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst

server time.bora.net
server time.konet.net

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.

 

NTP 서비스 시작, 확인 방법

-  ntp.conf 파일에 ntp 서비스에 사용할 서버를 추가 했으면 아래 명령어로 서비스 시작!

-  systemctl start ntpd.service ( 서비스 시작 )

-  systemctl status ntpd.service ( 서비스 상태 확인 )

-  Active : active 로 표시된다면 현재 NTP 서비스가 활성화된 상태

[root@localhost ~]# systemctl start ntpd.service
[root@localhost ~]# systemctl status ntpd.service
● ntpd.service - Network Time Service
   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2022-05-23 20:46:56 EDT; 3s ago
  Process: 4159 ExecStart=/usr/sbin/ntpd -u ntp:ntp $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 4160 (ntpd)
    Tasks: 1
   CGroup: /system.slice/ntpd.service
           └─4160 /usr/sbin/ntpd -u ntp:ntp -g

May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen and drop on 1 v6wildcard :: UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen normally on 2 lo 127.0.0.1 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen normally on 3 ens33 192.168.32.129 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen normally on 4 virbr0 192.168.122.1 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen normally on 5 ens33 fe80::ba71:6fed:e48d:4a90 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listen normally on 6 lo ::1 UDP 123
May 23 20:46:56 localhost.localdomain ntpd[4160]: Listening on routing socket on fd #23 for interface updates
May 23 20:46:56 localhost.localdomain ntpd[4160]: 0.0.0.0 c016 06 restart
May 23 20:46:56 localhost.localdomain ntpd[4160]: 0.0.0.0 c012 02 freq_set kernel -11.582 PPM

NTP 서비스에 연결된 서버 정보 및 연동 상태 확인 방법

-  ntpq -p

-  동기화 성공 시 서버 명 앞에 * 이 표시 된다

[root@localhost etc]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*time.bora.net   90.1.14.51       2 u   32   64    3   15.268  -31.360   7.743
 216.120.146.201 .INIT.          16 u    -  512    0    0.000    0.000   0.000