[linux] ntp 설정

환경 : Ubuntu 20.04

# ntp install
apt-get install ntp

# vi /etc/ntp.conf
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help

driftfile /var/lib/ntp/ntp.drift

# Leap seconds definition provided by tzdata
leapfile /usr/share/zoneinfo/leap-seconds.list

# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Specify one or more NTP servers.

# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
# pool 0.ubuntu.pool.ntp.org iburst # 주석
# pool 1.ubuntu.pool.ntp.org iburst # 주석
# pool 2.ubuntu.pool.ntp.org iburst # 주석
# pool 3.ubuntu.pool.ntp.org iburst # 주석

# Use Ubuntu's ntp server as a fallback.
# pool ntp.ubuntu.com # 주석
server 10.109.0.2 # ntp 받아올 서버 ip, domain 

# Hosts on local network are less restricted.
restrict 10.109.0.2 mask 255.255.255.192 nomodify notrap # ntp 받아올 대상 ip 추가

# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# Needed for adding pool entries
restrict source notrap nomodify noquery

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust


# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255

# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines.  Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient

 

ntp 확인

root@node1:~# ntpq -pn
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 10.109.0.2      193.123.243.2    3 u   32   64    1    0.594   17.819   0.000