man/timesyncd.conf.xml

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