1TIMESYNCD.CONF(5) timesyncd.conf TIMESYNCD.CONF(5)
2
6 timesyncd.conf, timesyncd.conf.d - Network Time Synchronization
7 configuration files
8
10 /etc/systemd/timesyncd.conf
11 /etc/systemd/timesyncd.conf.d/*.conf
13 /run/systemd/timesyncd.conf.d/*.conf
15 /usr/lib/systemd/timesyncd.conf.d/*.conf
17
19 These configuration files control NTP network time synchronization. See
20 systemd.syntax(7) for a general description of the syntax.
21
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.
31 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.
42 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.
51 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.
55
57 The following settings are configured in the [Time] section:
58 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.
68 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.
78 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 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.
88 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.
93 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=.
99 ConnectionRetrySec=
101 Specifies the minimum delay before subsequent attempts to contact a
102 new NTP server are made.
103 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.
107 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.
114 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.
118
120 systemd(1), systemd-timesyncd.service(8), systemd-networkd.service(8)
121systemd 254 TIMESYNCD.CONF(5)