chrony 설정

1. 설치되어 있지 않다면

yum install chrony

2. 설정파일

vi /etc/chrony.conf

3째줄 pool 2.centos.pool.ntp.org iburst 주석처리 하고

server time.bora.net iburst 입력

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
# pool 2.centos.pool.ntp.org iburst
server time.bora.net iburst

3. 데몬 재실행 & 재부팅시 자동시작 

systemctl restart chronyd
systemctl enable chronyd

4. 확인

chronyc sources

정상 가동시

MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^* time.bora.net                 2   6   337    57   -258us[  -17ms] +/-  553ms

비정상

===============================================================================
^? time.bora.net                 0   7     0     -     +0ns[   +0ns] +/-    0ns

방화벽 오픈 체크 할 것

outbound UDP 123