OpenNTPD

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OpenNTPD is a lightweight NTP server ported from OpenBSD.

Installation

USE flags

USE flags for net-misc/openntpd Lightweight NTP server ported from OpenBSD

constraints Enable HTTPS TLS time constraint support
selinux !!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
Data provided by the Gentoo Package Database · Last update: 2025年09月02日 17:00 More information about USE flags

Emerge

Install OpenNTPD:

root #emerge --ask net-misc/openntpd

Service

To ask OpenNTPD to attempt clock sync on startup, edit /etc/conf.d/ntpd:

FILE /etc/conf.d/ntpdGentoo OpenNTPD configuration file
# See ntpd(8) man page ... some popular options:
# -s Set the time immediately at startup
# (Note: may cause up to a 15 second startup delay
# if ntp servers not reachable)
NTPD_OPTS="-s"

Note that if the clock drift is sufficiently large, you may first need to set the time manually using date(1).

OpenRC

Start the ntp daemon:

root #/etc/init.d/ntpd start

Add the ntp daemon to the default runlevel:

root #rc-update add ntpd default

systemd

To enable and start the service now:

root #systemctl enable --now ntpd

Configuration

The default configuration file for OpenNTPD:

FILE /etc/ntpd.confGentoo's default configuration
# Addresses to listen on (ntpd does not listen by default)
#listen on *
# sync to a single server
#server ntp.example.org
# use a random selection of NTP Pool Time Servers
# see http://support.ntp.org/bin/view/Servers/NTPPoolServers
#servers pool.ntp.org
# use a specific local timedelta sensor (radio clock, etc)
#sensor nmea0
# use all detected timedelta sensors
#sensor *
# get the time constraint from a well-known HTTPS site
#constraints from "https://www.google.com/search?q=openntpd"
# Choose servers announced from Gentoo NTP Pool
servers 0.gentoo.pool.ntp.org
servers 1.gentoo.pool.ntp.org
servers 2.gentoo.pool.ntp.org
servers 3.gentoo.pool.ntp.org

For further information see the man page:

user $man ntpd.conf

Server

FILE /etc/ntpd.confOpenNTPD listening on 192.0.2.1 address while syncing with multiple servers
# Addresses to listen on (ntpd does not listen by default)
listen on 192.0.2.1
# Choose servers announced from Gentoo NTP Pool
servers 0.gentoo.pool.ntp.org
servers 1.gentoo.pool.ntp.org
servers 2.gentoo.pool.ntp.org
servers 3.gentoo.pool.ntp.org
root #rc-service ntpd restart

Client

FILE /etc/ntpd.confOpenNTPD syncing with multiple servers
# Choose servers announced from Gentoo NTP Pool
servers 0.gentoo.pool.ntp.org
servers 1.gentoo.pool.ntp.org
servers 2.gentoo.pool.ntp.org
servers 3.gentoo.pool.ntp.org

Alternatively sync the client to a server on the local network:

FILE /etc/ntpd.confOpenNTPD syncing with a single server on the local network
# sync to a single server on the local network
server 192.0.2.1
root #rc-service ntpd restart

Checking the daemon operation

net-misc/openntpd provides the /usr/sbin/ntpctl program to display information about the running ntpd daemon:

root #ntpctl -s all
4/4 peers valid, clock unsynced, clock offset is 1048.342ms
peer
 wt tl st next poll offset delay jitter
185.19.184.35 0.gentoo.pool.ntp.org
 1 10 2 23s 34s 41.650ms 190.744ms 227.001ms
31.14.131.188 1.gentoo.pool.ntp.org
 1 10 2 2s 31s 15.834ms 132.072ms 92.419ms
212.45.144.3 2.gentoo.pool.ntp.org
 1 10 1 8s 33s 42.733ms 216.937ms 212.899ms
188.213.165.209 3.gentoo.pool.ntp.org
 1 10 2 19s 30s 45.672ms 228.337ms 240.018ms

The output shows how many servers the daemon is syncing with, the status of the system clock (synced/unsynced) and the clock offset. For further information see the man page:

user $man ntpctl

See also