1TIMESYNCD.CONF(5)               timesyncd.conf               TIMESYNCD.CONF(5)
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NAME

6       timesyncd.conf, timesyncd.conf.d - Network Time Synchronization
7       configuration files
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SYNOPSIS

10       /etc/systemd/timesyncd.conf
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12       /etc/systemd/timesyncd.conf.d/*.conf
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14       /run/systemd/timesyncd.conf.d/*.conf
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16       /usr/lib/systemd/timesyncd.conf.d/*.conf
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DESCRIPTION

19       These configuration files control NTP network time synchronization. See
20       systemd.syntax(7) for a general description of the syntax.
21

CONFIGURATION DIRECTORIES AND PRECEDENCE

23       The default configuration is set during compilation, so configuration
24       is only needed when it is necessary to deviate from those defaults.
25       Initially, the main configuration file in /etc/systemd/ contains
26       commented out entries showing the defaults as a guide to the
27       administrator. Local overrides can be created by editing this file or
28       by creating drop-ins, as described below. Using drop-ins for local
29       configuration is recommended over modifications to the main
30       configuration file.
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32       In addition to the "main" configuration file, drop-in configuration
33       snippets are read from /usr/lib/systemd/*.conf.d/,
34       /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/. Those
35       drop-ins have higher precedence and override the main configuration
36       file. Files in the *.conf.d/ configuration subdirectories are sorted by
37       their filename in lexicographic order, regardless of in which of the
38       subdirectories they reside. When multiple files specify the same
39       option, for options which accept just a single value, the entry in the
40       file sorted last takes precedence, and for options which accept a list
41       of values, entries are collected as they occur in the sorted files.
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43       When packages need to customize the configuration, they can install
44       drop-ins under /usr/. Files in /etc/ are reserved for the local
45       administrator, who may use this logic to override the configuration
46       files installed by vendor packages. Drop-ins have to be used to
47       override package drop-ins, since the main configuration file has lower
48       precedence. It is recommended to prefix all filenames in those
49       subdirectories with a two-digit number and a dash, to simplify the
50       ordering of the files.
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52       To disable a configuration file supplied by the vendor, the recommended
53       way is to place a symlink to /dev/null in the configuration directory
54       in /etc/, with the same filename as the vendor configuration file.
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OPTIONS

57       The following settings are configured in the [Time] section:
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59       NTP=
60           A space-separated list of NTP server host names or IP addresses.
61           During runtime this list is combined with any per-interface NTP
62           servers acquired from systemd-networkd.service(8).
63           systemd-timesyncd will contact all configured system or
64           per-interface servers in turn, until one responds. When the empty
65           string is assigned, the list of NTP servers is reset, and all prior
66           assignments will have no effect. This setting defaults to an empty
67           list.
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69       FallbackNTP=
70           A space-separated list of NTP server host names or IP addresses to
71           be used as the fallback NTP servers. Any per-interface NTP servers
72           obtained from systemd-networkd.service(8) take precedence over this
73           setting, as do any servers set via NTP= above. This setting is
74           hence only relevant if no other NTP server information is known.
75           When the empty string is assigned, the list of NTP servers is
76           reset, and all prior assignments will have no effect. If this
77           option is not given, a compiled-in list of NTP servers is used.
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79       RootDistanceMaxSec=
80           Maximum acceptable root distance, i.e. the maximum estimated time
81           required for a packet to travel to the server we are connected to
82           from the server with the reference clock. If the current server
83           does not satisfy this limit, systemd-timesyncd will switch to a
84           different server.
85
86           Takes a time span value. The default unit is seconds, but other
87           units may be specified, see systemd.time(5). Defaults to 5 seconds.
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89       PollIntervalMinSec=, PollIntervalMaxSec=
90           The minimum and maximum poll intervals for NTP messages. Polling
91           starts at the minimum poll interval, and is adjusted within the
92           specified limits in response to received packets.
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94           Each setting takes a time span value. The default unit is seconds,
95           but other units may be specified, see systemd.time(5).
96           PollIntervalMinSec= defaults to 32 seconds and must not be smaller
97           than 16 seconds.  PollIntervalMaxSec= defaults to 34 min 8 s
98           (2048 seconds) and must be larger than PollIntervalMinSec=.
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100       ConnectionRetrySec=
101           Specifies the minimum delay before subsequent attempts to contact a
102           new NTP server are made.
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104           Takes a time span value. The default unit is seconds, but other
105           units may be specified, see systemd.time(5). Defaults to 30 seconds
106           and must not be smaller than 1 second.
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108       SaveIntervalSec=
109           The interval at which the current time is periodically saved to
110           disk, in the absence of any recent synchronisation from an NTP
111           server. This is especially useful for offline systems with no local
112           RTC, as it will guarantee that the system clock remains roughly
113           monotonic across reboots.
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115           Takes a time interval value. The default unit is seconds, but other
116           units may be specified, see systemd.time(5). Defaults to 60
117           seconds.
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SEE ALSO

120       systemd(1), systemd-timesyncd.service(8), systemd-networkd.service(8)
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124systemd 254                                                  TIMESYNCD.CONF(5)
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