pubroot

apt update && apt install -y chrony

timedatectl set-timezone Asia/Seoul

vi /etc/chrony/chrony.conf

### vi ###
# pool 2.debian.pool.ntp.org iburst
allow 0.0.0.0/0
local stratum 1
### vi ###

systemctl restart chrony

pubroot 제외 모든 디바이스

apt update && apt install -y chrony

timedatectl set-timezone Asia/Seoul

vi /etc/chrony/chrony.conf

### vi ###
server 1.1.1.100 iburst
### vi ###

systemctl restart chrony