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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: 2024-09-12 18:37 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

• Ntp — is a suite of tools utilizing Network Time Protocol. Their purpose is to keep the system clock in time.
• Chrony — a versatile implementation of the Network Time Protocol (NTP).
• Network Time Protocol — is used to synchronize the system time with other devices over the network.
• System time — is used in Unix systems to keep track of time.
• Home router — how to turn an old Gentoo machine into a router for connecting a home network to the Internet.