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.TH "TIMESYNCD\&.CONF" "5" "" "systemd 256~rc1" "timesyncd.conf"
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.SH "NAME"
timesyncd.conf, timesyncd.conf.d \- Network Time Synchronization configuration files
.SH "SYNOPSIS"
.PP
.RS 4
/etc/systemd/timesyncd\&.conf
.RE
.RS 4
/run/systemd/timesyncd\&.conf
.RE
.RS 4
/usr/lib/systemd/timesyncd\&.conf
.RE
.RS 4
/etc/systemd/timesyncd\&.conf\&.d/*\&.conf
.RE
.RS 4
/run/systemd/timesyncd\&.conf\&.d/*\&.conf
.RE
.RS 4
/usr/lib/systemd/timesyncd\&.conf\&.d/*\&.conf
.RE
.SH "DESCRIPTION"
.PP
These configuration files control NTP network time synchronization\&. See
\fBsystemd.syntax\fR(7)
for a general description of the syntax\&.
.SH "CONFIGURATION DIRECTORIES AND PRECEDENCE"
.PP
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/,
/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\*(Aqs shipped under
/usr/), however using drop\-ins for local configuration is recommended over modifications to the main configuration file\&.
.PP
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\&.
.PP
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 of the files\&. 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\&.
.PP
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\&.
.SH "OPTIONS"
.PP
The following settings are configured in the [Time] section:
.PP
\fINTP=\fR
.RS 4
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
\fBsystemd-networkd.service\fR(8)\&.
\fBsystemd\-timesyncd\fR
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\&.
.sp
Added in version 216\&.
.RE
.PP
\fIFallbackNTP=\fR
.RS 4
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
\fBsystemd-networkd.service\fR(8)
take precedence over this setting, as do any servers set via
\fINTP=\fR
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\&.
.sp
Added in version 216\&.
.RE
.PP
\fIRootDistanceMaxSec=\fR
.RS 4
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,
\fBsystemd\-timesyncd\fR
will switch to a different server\&.
.sp
Takes a time span value\&. The default unit is seconds, but other units may be specified, see
\fBsystemd.time\fR(5)\&. Defaults to 5 seconds\&.
.sp
Added in version 236\&.
.RE
.PP
\fIPollIntervalMinSec=\fR, \fIPollIntervalMaxSec=\fR
.RS 4
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\&.
.sp
Each setting takes a time span value\&. The default unit is seconds, but other units may be specified, see
\fBsystemd.time\fR(5)\&.
\fIPollIntervalMinSec=\fR
defaults to 32 seconds and must not be smaller than 16\ \&seconds\&.
\fIPollIntervalMaxSec=\fR
defaults to 34\ \&min\ \&8\ \&s (2048\ \&seconds) and must be larger than
\fIPollIntervalMinSec=\fR\&.
.sp
Added in version 236\&.
.RE
.PP
\fIConnectionRetrySec=\fR
.RS 4
Specifies the minimum delay before subsequent attempts to contact a new NTP server are made\&.
.sp
Takes a time span value\&. The default unit is seconds, but other units may be specified, see
\fBsystemd.time\fR(5)\&. Defaults to 30 seconds and must not be smaller than 1 second\&.
.sp
Added in version 248\&.
.RE
.PP
\fISaveIntervalSec=\fR
.RS 4
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\&.
.sp
Takes a time interval value\&. The default unit is seconds, but other units may be specified, see
\fBsystemd.time\fR(5)\&. Defaults to 60 seconds\&.
.sp
Added in version 250\&.
.RE
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1), \fBsystemd-timesyncd.service\fR(8), \fBsystemd-networkd.service\fR(8)