NAME

       timesyncd.conf, timesyncd.conf.d - Network Time Synchronization configuration files

SYNOPSIS

           /etc/systemd/timesyncd.conf
           /run/systemd/timesyncd.conf
           /usr/local/lib/systemd/timesyncd.conf
           /usr/lib/systemd/timesyncd.conf
           /etc/systemd/timesyncd.conf.d/*.conf
           /run/systemd/timesyncd.conf.d/*.conf
           /usr/local/lib/systemd/timesyncd.conf.d/*.conf
           /usr/lib/systemd/timesyncd.conf.d/*.conf

DESCRIPTION

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

CONFIGURATION DIRECTORIES AND PRECEDENCE

       The default configuration is set during compilation, so configuration is only needed when
       it is necessary to deviate from those defaults. The main configuration file is loaded from
       one of the listed directories in order of priority, only the first file found is used:
       /etc/systemd/, /run/systemd/, /usr/local/lib/systemd/ [1], /usr/lib/systemd/. The vendor
       version of the file contains commented out entries showing the defaults as a guide to the
       administrator. Local overrides can also be created by creating drop-ins, as described
       below. The main configuration file can also be edited for this purpose (or a copy in /etc/
       if it's shipped under /usr/), however using drop-ins for local configuration is
       recommended over modifications to the main configuration file.

       In addition to the main configuration file, drop-in configuration snippets are read from
       /usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/.
       Those drop-ins have higher precedence and override the main configuration file. Files in
       the *.conf.d/ configuration subdirectories are sorted by their filename in lexicographic
       order, regardless of in which of the subdirectories they reside. When multiple files
       specify the same option, for options which accept just a single value, the entry in the
       file sorted last takes precedence, and for options which accept a list of values, entries
       are collected as they occur in the sorted files.

       When packages need to customize the configuration, they can install drop-ins under /usr/.
       Files in /etc/ are reserved for the local administrator, who may use this logic to
       override the configuration files installed by vendor packages. Drop-ins have to be used to
       override package drop-ins, since the main configuration file has lower precedence. It is
       recommended to prefix all filenames in those subdirectories with a two-digit number and a
       dash, to simplify the ordering. This also defines a concept of drop-in priorities to allow
       OS vendors to ship drop-ins within a specific range lower than the range used by users.
       This should lower the risk of package drop-ins overriding accidentally drop-ins defined by
       users. It is recommended to use the range 10-40 for drop-ins in /usr/ and the range 60-90
       for drop-ins in /etc/ and /run/, to make sure that local and transient drop-ins take
       priority over drop-ins shipped by the OS vendor.

       To disable a configuration file supplied by the vendor, the recommended way is to place a
       symlink to /dev/null in the configuration directory in /etc/, with the same filename as
       the vendor configuration file.

OPTIONS

       The following settings are configured in the [Time] section:

       NTP=
           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 systemd-
           networkd.service(8).  systemd-timesyncd 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.

           Added in version 216.

       FallbackNTP=
           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 systemd-
           networkd.service(8) take precedence over this setting, as do any servers set via NTP=
           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.

           Added in version 216.

       RootDistanceMaxSec=
           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, systemd-timesyncd will
           switch to a different server.

           Takes a time span value. The default unit is seconds, but other units may be
           specified, see systemd.time(5). Defaults to 5 seconds.

           Added in version 236.

       PollIntervalMinSec=, PollIntervalMaxSec=
           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.

           Each setting takes a time span value. The default unit is seconds, but other units may
           be specified, see systemd.time(5).  PollIntervalMinSec= defaults to 32 seconds and
           must not be smaller than 16 seconds.  PollIntervalMaxSec= defaults to 34 min 8 s
           (2048 seconds) and must be larger than PollIntervalMinSec=.

           Added in version 236.

       ConnectionRetrySec=
           Specifies the minimum delay before subsequent attempts to contact a new NTP server are
           made.

           Takes a time span value. The default unit is seconds, but other units may be
           specified, see systemd.time(5). Defaults to 30 seconds and must not be smaller than 1
           second.

           Added in version 248.

       SaveIntervalSec=
           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.

           Takes a time interval value. The default unit is seconds, but other units may be
           specified, see systemd.time(5). Defaults to 60 seconds.

           Added in version 250.

SEE ALSO

       systemd(1), systemd-timesyncd.service(8), systemd-networkd.service(8)

NOTES

        1. 💣💥🧨💥💥💣 Please note that those configuration files must be available at all times.
           If /usr/local/ is a separate partition, it may not be available during early boot, and
           must not be used for configuration.