man/timesyncd.conf.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2014 Lennart Poettering
  11 -->
  12
  13 <refentry id="timesyncd.conf" conditional='ENABLE_TIMESYNCD'
  14     xmlns:xi="http://www.w3.org/2001/XInclude">
  15   <refentryinfo>
  16     <title>timesyncd.conf</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>Developer</contrib>
  22         <firstname>Lennart</firstname>
  23         <surname>Poettering</surname>
  24         <email>lennart@poettering.net</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>timesyncd.conf</refentrytitle>
  31     <manvolnum>5</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>timesyncd.conf</refname>
  36     <refname>timesyncd.conf.d</refname>
  37     <refpurpose>Network Time Synchronization configuration files</refpurpose>
  38   </refnamediv>
  39
  40   <refsynopsisdiv>
  41     <para><filename>/etc/systemd/timesyncd.conf</filename></para>
  42     <para><filename>/etc/systemd/timesyncd.conf.d/*.conf</filename></para>
  43     <para><filename>/run/systemd/timesyncd.conf.d/*.conf</filename></para>
  44     <para><filename>/usr/lib/systemd/timesyncd.conf.d/*.conf</filename></para>
  45   </refsynopsisdiv>
  46
  47   <refsect1>
  48     <title>Description</title>
  49
  50     <para>These configuration files control NTP network time synchronization. See
  51     <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  52     for a general description of the syntax.</para>
  53   </refsect1>
  54
  55   <xi:include href="standard-conf.xml" xpointer="main-conf" />
  56
  57   <refsect1>
  58     <title>Options</title>
  59
  60     <para>The following settings are configured in the <literal>[Time]</literal> section:</para>
  61
  62     <variablelist class='network-directives'>
  63
  64       <varlistentry>
  65         <term><varname>NTP=</varname></term>
  66         <listitem><para>A space-separated list of NTP server host
  67         names or IP addresses. During runtime this list is combined
  68         with any per-interface NTP servers acquired from
  69         <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  70         systemd-timesyncd will contact all configured system or
  71         per-interface servers in turn until one is found that
  72         responds. When the empty string is assigned, the list of
  73         NTP servers is reset, and all assignments prior to this one
  74         will have no effect. This setting defaults to an empty
  75         list.</para></listitem>
  76       </varlistentry>
  77
  78       <varlistentry>
  79         <term><varname>FallbackNTP=</varname></term>
  80         <listitem><para>A space-separated list of NTP server host
  81         names or IP addresses to be used as the fallback NTP servers.
  82         Any per-interface NTP servers obtained from
  83         <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  84         take precedence over this setting, as do any servers set via
  85         <varname>NTP=</varname> above. This setting is hence only used
  86         if no other NTP server information is known. When the empty
  87         string is assigned, the list of NTP servers is reset,
  88         and all assignments prior to this one will have no effect.
  89         If this option is not given, a compiled-in list of NTP servers
  90         is used instead.</para></listitem>
  91       </varlistentry>
  92
  93       <varlistentry>
  94         <term><varname>RootDistanceMaxSec=</varname></term>
  95         <listitem><para>Maximum acceptable root distance. Takes a time value (in seconds).
  96         Defaults to 5 seconds.</para></listitem>
  97       </varlistentry>
  98
  99       <varlistentry>
 100         <term><varname>PollIntervalMinSec=</varname></term>
 101         <term><varname>PollIntervalMaxSec=</varname></term>
 102         <listitem><para>The minimum and maximum poll intervals for NTP messages.
 103         Each setting takes a time value (in seconds).
 104         <varname>PollIntervalMinSec=</varname> must not be smaller than 16 seconds.
 105         <varname>PollIntervalMaxSec=</varname> must be larger than <varname>PollIntervalMinSec=</varname>.
 106         <varname>PollIntervalMinSec=</varname> defaults to 32 seconds, and
 107         <varname>PollIntervalMaxSec=</varname> defaults to 2048 seconds.</para></listitem>
 108       </varlistentry>
 109
 110     </variablelist>
 111   </refsect1>
 112
 113   <refsect1>
 114       <title>See Also</title>
 115       <para>
 116       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 117       <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 118       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 119       </para>
 120   </refsect1>
 121
 122 </refentry>