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