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| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
| "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
| |
| <refentry id="timesyncd.conf" conditional='ENABLE_TIMESYNCD' |
| xmlns:xi="http://www.w3.org/2001/XInclude"> |
| <refentryinfo> |
| <title>timesyncd.conf</title> |
| <productname>systemd</productname> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>timesyncd.conf</refentrytitle> |
| <manvolnum>5</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>timesyncd.conf</refname> |
| <refname>timesyncd.conf.d</refname> |
| <refpurpose>Network Time Synchronization configuration files</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <para><filename>/etc/systemd/timesyncd.conf</filename></para> |
| <para><filename>/etc/systemd/timesyncd.conf.d/*.conf</filename></para> |
| <para><filename>/run/systemd/timesyncd.conf.d/*.conf</filename></para> |
| <para><filename>/usr/lib/systemd/timesyncd.conf.d/*.conf</filename></para> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>These configuration files control NTP network time synchronization. See |
| <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
| for a general description of the syntax.</para> |
| </refsect1> |
| |
| <xi:include href="standard-conf.xml" xpointer="main-conf" /> |
| |
| <refsect1> |
| <title>Options</title> |
| |
| <para>The following settings are configured in the [Time] section:</para> |
| |
| <variablelist class='network-directives'> |
| |
| <varlistentry> |
| <term><varname>NTP=</varname></term> |
| <listitem><para>A space-separated list of NTP server host names or IP addresses. During runtime this |
| list is combined with any per-interface NTP servers acquired from |
| <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. |
| <command>systemd-timesyncd</command> will contact all configured system or per-interface servers in |
| turn, until one responds. When the empty string is assigned, the list of NTP servers is reset, and |
| all prior assignments will have no effect. This setting defaults to an empty list.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>FallbackNTP=</varname></term> |
| <listitem><para>A space-separated list of NTP server host names or IP addresses to be used as the |
| fallback NTP servers. Any per-interface NTP servers obtained from |
| <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| take precedence over this setting, as do any servers set via <varname>NTP=</varname> above. This |
| setting is hence only relevant if no other NTP server information is known. When the empty string is |
| assigned, the list of NTP servers is reset, and all prior assignments will have no effect. If this |
| option is not given, a compiled-in list of NTP servers is used.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>RootDistanceMaxSec=</varname></term> |
| <listitem><para>Maximum acceptable root distance, i.e. the maximum estimated time required for a |
| packet to travel to the server we are connected to from the server with the reference clock. If |
| the current server does not satisfy this limit, <command>systemd-timesyncd</command> will switch |
| to a different server.</para> |
| |
| <para>Takes a time span value. The default unit is seconds, but other units may be specified, see |
| <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
| Defaults to 5 seconds.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>PollIntervalMinSec=</varname></term> |
| <term><varname>PollIntervalMaxSec=</varname></term> |
| <listitem><para>The minimum and maximum poll intervals for NTP messages. Polling starts at the |
| minimum poll interval, and is adjusted within the specified limits in response to received packets. |
| </para> |
| |
| <para>Each setting takes a time span value. The default unit is seconds, but other units may be |
| specified, see |
| <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
| <varname>PollIntervalMinSec=</varname> defaults to 32 seconds and must not be smaller than |
| 16 seconds. <varname>PollIntervalMaxSec=</varname> defaults to 34 min 8 s (2048 seconds) and must be |
| larger than <varname>PollIntervalMinSec=</varname>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>ConnectionRetrySec=</varname></term> |
| <listitem><para>Specifies the minimum delay before subsequent attempts to contact a new NTP server |
| are made.</para> |
| |
| <para>Takes a time span value. The default unit is seconds, but other units may be specified, see |
| <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
| Defaults to 30 seconds and must not be smaller than 1 second.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>SaveIntervalSec=</varname></term> |
| <listitem><para>The interval at which the current time is periodically saved to disk, in the absence |
| of any recent synchronisation from an NTP server. This is especially useful for offline systems |
| with no local RTC, as it will guarantee that the system clock remains roughly monotonic across |
| reboots.</para> |
| |
| <para>Takes a time interval value. The default unit is seconds, but other units may be specified, see |
| <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
| Defaults to 60 seconds.</para></listitem> |
| </varlistentry> |
| |
| </variablelist> |
| </refsect1> |
| |
| <refsect1> |
| <title>See Also</title> |
| <para> |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |