Use NTP service to sync time on Debian
By Baishun on Mar 5, 2023
Summary
Time is very is important on Linux, especially for the apps use timestamp as an important value to do things like signature. So we need to make sure the time is synced with the internet server.
A very easy way to do this is to use NTP service.
tips: you can use date command to check if the time is same with the internet
Install
On Debian, we use this command to install ntp service:
sudo apt update && sudo apt install ntp -yIf success, you may got response like this:
... a lot of outputs here...
Reading package lists... Done
Building dependency tree
Reading state information... Done
Selecting previously unselected package libevent-pthreads-2.1-6:amd64.
Preparing to unpack .../libevent-pthreads-2.1-6_2.1.8-stable-4_amd64.deb ...
Unpacking libevent-pthreads-2.1-6:amd64 (2.1.8-stable-4) ...
Selecting previously unselected package libopts25:amd64.
Preparing to unpack .../libopts25_1%3a5.18.12-4_amd64.deb ...
Unpacking libopts25:amd64 (1:5.18.12-4) ...
Selecting previously unselected package ntp.
Preparing to unpack .../ntp_1%3a4.2.8p12+dfsg-4_amd64.deb ...
Unpacking ntp (1:4.2.8p12+dfsg-4) ...
Selecting previously unselected package sntp.
Preparing to unpack .../sntp_1%3a4.2.8p12+dfsg-4_amd64.deb ...
Unpacking sntp (1:4.2.8p12+dfsg-4) ...
Setting up libopts25:amd64 (1:5.18.12-4) ...
Setting up ntp (1:4.2.8p12+dfsg-4) ...
Created symlink /etc/systemd/system/multi-user.target.wants/ntp.service → /lib/systemd/system/ntp.service.
Setting up libevent-core-2.1-6:amd64 (2.1.8-stable-4) ...
Setting up libevent-pthreads-2.1-6:amd64 (2.1.8-stable-4) ...
Setting up sntp (1:4.2.8p12+dfsg-4) ...
Processing triggers for systemd (241-7~deb10u10) ...
Processing triggers for man-db (2.8.5-2+deb10u1) ...
Processing triggers for libc-bin (2.28-10+deb10u2) ...
After installation, you will find the config file is created automaticly, we can check the file contents with this command: cat /etc/ntp.conf and the output is like this:
# /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
# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example
# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
# pick a different set every time it starts up. Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
pool 0.debian.pool.ntp.org iburst
pool 1.debian.pool.ntp.org iburst
pool 2.debian.pool.ntp.org iburst
pool 3.debian.pool.ntp.org iburst
# 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.
18 #server ntp.your-provider.example
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
To make sure the service is run correctly, we can restart it by using this command:
sudo systemctl restart ntpand you can check the staus of ntp with ntpq -p:
remote refid st t when poll reach delay offset jitter
==============================================================================
0.debian.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000
1.debian.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000
2.debian.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000
3.debian.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000
79.133.44.140 .MBGh. 1 u 1 64 1 1.147 2.770 0.189
time.cloudflare 10.96.8.7 3 u 2 64 1 1.030 1.909 0.000
ntp.creoline.ne 131.188.3.222 2 u 1 64 1 0.991 2.996 0.000
saiph.pmsf.net 131.188.3.220 2 u 1 64 1 5.582 3.532 0.000
That’s It!