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874ff7bf | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
874ff7bf | 5 | |
be795898 | 6 | <refentry id="timesyncd.conf" conditional='ENABLE_TIMESYNCD' |
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7 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
8 | <refentryinfo> | |
9 | <title>timesyncd.conf</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>timesyncd.conf</refentrytitle> | |
15 | <manvolnum>5</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>timesyncd.conf</refname> | |
20 | <refname>timesyncd.conf.d</refname> | |
21 | <refpurpose>Network Time Synchronization configuration files</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
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25 | <para><filename>/etc/systemd/timesyncd.conf</filename></para> |
26 | <para><filename>/etc/systemd/timesyncd.conf.d/*.conf</filename></para> | |
798d3a52 | 27 | <para><filename>/run/systemd/timesyncd.conf.d/*.conf</filename></para> |
12b42c76 | 28 | <para><filename>/usr/lib/systemd/timesyncd.conf.d/*.conf</filename></para> |
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29 | </refsynopsisdiv> |
30 | ||
31 | <refsect1> | |
32 | <title>Description</title> | |
33 | ||
0f943ae4 | 34 | <para>These configuration files control NTP network time synchronization. See |
675fa6ea | 35 | <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>7</manvolnum></citerefentry> |
0f943ae4 | 36 | for a general description of the syntax.</para> |
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37 | </refsect1> |
38 | ||
e93549ef | 39 | <xi:include href="standard-conf.xml" xpointer="main-conf" /> |
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40 | |
41 | <refsect1> | |
42 | <title>Options</title> | |
43 | ||
bdac5608 | 44 | <para>The following settings are configured in the [Time] section:</para> |
6c033c34 | 45 | |
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46 | <variablelist class='network-directives'> |
47 | ||
48 | <varlistentry> | |
49 | <term><varname>NTP=</varname></term> | |
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50 | <listitem><para>A space-separated list of NTP server host names or IP addresses. During runtime this |
51 | list is combined with any per-interface NTP servers acquired from | |
798d3a52 | 52 | <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. |
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53 | <command>systemd-timesyncd</command> will contact all configured system or per-interface servers in |
54 | turn, until one responds. When the empty string is assigned, the list of NTP servers is reset, and | |
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55 | all prior assignments will have no effect. This setting defaults to an empty list.</para> |
56 | ||
57 | <xi:include href="version-info.xml" xpointer="v216"/></listitem> | |
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58 | </varlistentry> |
59 | ||
60 | <varlistentry> | |
61 | <term><varname>FallbackNTP=</varname></term> | |
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62 | <listitem><para>A space-separated list of NTP server host names or IP addresses to be used as the |
63 | fallback NTP servers. Any per-interface NTP servers obtained from | |
798d3a52 | 64 | <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
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65 | take precedence over this setting, as do any servers set via <varname>NTP=</varname> above. This |
66 | setting is hence only relevant if no other NTP server information is known. When the empty string is | |
67 | assigned, the list of NTP servers is reset, and all prior assignments will have no effect. If this | |
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68 | option is not given, a compiled-in list of NTP servers is used.</para> |
69 | ||
70 | <xi:include href="version-info.xml" xpointer="v216"/></listitem> | |
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71 | </varlistentry> |
72 | ||
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73 | <varlistentry> |
74 | <term><varname>RootDistanceMaxSec=</varname></term> | |
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75 | <listitem><para>Maximum acceptable root distance, i.e. the maximum estimated time required for a |
76 | packet to travel to the server we are connected to from the server with the reference clock. If | |
77 | the current server does not satisfy this limit, <command>systemd-timesyncd</command> will switch | |
78 | to a different server.</para> | |
79 | ||
fc070a25 | 80 | <para>Takes a time span value. The default unit is seconds, but other units may be specified, see |
c91ebcdb | 81 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
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82 | Defaults to 5 seconds.</para> |
83 | ||
84 | <xi:include href="version-info.xml" xpointer="v236"/></listitem> | |
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85 | </varlistentry> |
86 | ||
a4465d0d YW |
87 | <varlistentry> |
88 | <term><varname>PollIntervalMinSec=</varname></term> | |
89 | <term><varname>PollIntervalMaxSec=</varname></term> | |
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90 | <listitem><para>The minimum and maximum poll intervals for NTP messages. Polling starts at the |
91 | minimum poll interval, and is adjusted within the specified limits in response to received packets. | |
92 | </para> | |
93 | ||
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94 | <para>Each setting takes a time span value. The default unit is seconds, but other units may be |
95 | specified, see | |
96 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
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97 | <varname>PollIntervalMinSec=</varname> defaults to 32 seconds and must not be smaller than |
98 | 16 seconds. <varname>PollIntervalMaxSec=</varname> defaults to 34 min 8 s (2048 seconds) and must be | |
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99 | larger than <varname>PollIntervalMinSec=</varname>.</para> |
100 | ||
101 | <xi:include href="version-info.xml" xpointer="v236"/></listitem> | |
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102 | </varlistentry> |
103 | ||
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104 | <varlistentry> |
105 | <term><varname>ConnectionRetrySec=</varname></term> | |
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106 | <listitem><para>Specifies the minimum delay before subsequent attempts to contact a new NTP server |
107 | are made.</para> | |
108 | ||
fc070a25 | 109 | <para>Takes a time span value. The default unit is seconds, but other units may be specified, see |
c91ebcdb | 110 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. |
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111 | Defaults to 30 seconds and must not be smaller than 1 second.</para> |
112 | ||
113 | <xi:include href="version-info.xml" xpointer="v248"/></listitem> | |
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114 | </varlistentry> |
115 | ||
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116 | <varlistentry> |
117 | <term><varname>SaveIntervalSec=</varname></term> | |
118 | <listitem><para>The interval at which the current time is periodically saved to disk, in the absence | |
119 | of any recent synchronisation from an NTP server. This is especially useful for offline systems | |
120 | with no local RTC, as it will guarantee that the system clock remains roughly monotonic across | |
121 | reboots.</para> | |
122 | ||
123 | <para>Takes a time interval value. The default unit is seconds, but other units may be specified, see | |
124 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>. | |
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125 | Defaults to 60 seconds.</para> |
126 | ||
127 | <xi:include href="version-info.xml" xpointer="v250"/></listitem> | |
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128 | </varlistentry> |
129 | ||
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130 | </variablelist> |
131 | </refsect1> | |
132 | ||
133 | <refsect1> | |
134 | <title>See Also</title> | |
135 | <para> | |
136 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
137 | <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
138 | <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
139 | </para> | |
140 | </refsect1> | |
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141 | |
142 | </refentry> |