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SNTP(8)			  BSD System Manager's Manual		       SNTP(8)

NAME
     sntp -- standard Simple Network Time Protocol client program

SYNOPSIS
     sntp [-flags] [-flag [value]] [--option-name[[=| ]value]] [ host-
	  name-or-IP ...]

DESCRIPTION
     sntp can be used as an SNTP client	to query a NTP or SNTP server and ei-
     ther display the time or set the local system's time (given suitable
     privilege).  It can be run	as an interactive command or from a cron job.
     NTP (the Network Time Protocol) and SNTP (the Simple Network Time Proto-
     col) are defined and described by RFC 5905.

     The default is to write the estimated correct local date and time (i.e.
     not UTC) to the standard output in	a format like: '1996-10-15
     20:17:25.123 (+0800) +4.567 +/- 0.089 [host] IP sN' where the '(+0800)'
     means that	to get to UTC from the reported	local time one must add	8
     hours and 0 minutes, the '+4.567' indicates the local clock is 4.567 sec-
     onds behind the correct time (so 4.567 seconds must be added to the local
     clock to get it to	be correct).  Note that	the number of decimals printed
     for this value will change	based on the reported precision	of the server.
     '+/- 0.089' is the	reported synchronization distance (in seconds),	which
     represents	the maximum error due to all causes.  If the server does not
     report valid data needed to calculate the synchronization distance, this
     will be reported as '+/- ?'.  If the host is different from the IP, both
     will be displayed.	 Otherwise, only the IP	is displayed.  Finally,	the
     stratum of	the host is reported and the leap indicator is decoded and
     displayed.

OPTIONS
     -4, --ipv4
	     Force IPv4	DNS name resolution.  This option must not appear in
	     combination with any of the following options: ipv6.

	     Force DNS resolution of the following host	names on the command
	     line to the IPv4 namespace.

     -6, --ipv6
	     Force IPv6	DNS name resolution.  This option must not appear in
	     combination with any of the following options: ipv4.

	     Force DNS resolution of the following host	names on the command
	     line to the IPv6 namespace.

     -a	auth-keynumber,	--authentication=auth-keynumber
	     Enable authentication with	the key	auth-keynumber.	 This option
	     takes an integer number as	its argument.

	     Enable authentication using the key specified in this option's
	     argument.	The argument of	this option is the keyid, a number
	     specified in the keyfile as this key's identifier.	 See the key-
	     file option (-k) for more details.

     -b	broadcast-address, --broadcast=broadcast-address
	     Listen to the address specified for broadcast time	sync.  This
	     option may	appear an unlimited number of times.

	     If	specified sntp will listen to the specified address for	NTP
	     broadcasts.  The default maximum wait time	can (and probably
	     should) be	modified with -t.

     -c	host-name, --concurrent=host-name
	     Concurrently query	all IPs	returned for host-name.	 This option
	     may appear	an unlimited number of times.

	     Requests from an NTP "client" to a	"server" should	never be sent
	     more rapidly than one every 2 seconds.  By	default, any IPs re-
	     turned as part of a DNS lookup are	assumed	to be for a single in-
	     stance of ntpd, and therefore sntp	will send queries to these IPs
	     one after another,	with a 2-second	gap in between each query.

	     The -c or --concurrent flag says that any IPs returned for	the
	     DNS lookup	of the supplied	host-name are on different machines,
	     so	we can send concurrent queries.

     -d, --debug-level
	     Increase debug verbosity level.  This option may appear an	unlim-
	     ited number of times.

     -D	number,	--set-debug-level=number
	     Set the debug verbosity level.  This option may appear an unlim-
	     ited number of times.  This option	takes an integer number	as its
	     argument.

     -g	milliseconds, --gap=milliseconds
	     The gap (in milliseconds) between time requests.  This option
	     takes an integer number as	its argument.  The default
	     milliseconds for this option is:
		  50

	     Since we're only going to use the first valid response we get and
	     there is benefit to specifying a good number of servers to	query,
	     separate the queries we send out by the specified number of mil-
	     liseconds.

     -K	file-name, --kod=file-name
	     KoD history filename.  The	default	file-name for this option is:
		  /var/db/ntp-kod

	     Specifies the filename to be used for the persistent history of
	     KoD responses received from servers.  If the file does not	exist,
	     a warning message will be displayed.  The file will not be	cre-
	     ated.

     -k	file-name, --keyfile=file-name
	     Look in this file for the key specified with -a.

	     This option specifies the keyfile.	 sntp will search for the key
	     specified with -a keyno in	this file.  See	ntp.keys(5) for	more
	     information.

     -l	file-name, --logfile=file-name
	     Log to specified logfile.

	     This option causes	the client to write log	messages to the	speci-
	     fied logfile.

     -M	number,	--steplimit=number
	     Adjustments less than steplimit msec will be slewed.  This	option
	     takes an integer number as	its argument.  The value of number is
	     constrained to being:
		 greater than or equal to 0

	     If	the time adjustment is less than steplimit milliseconds, slew
	     the amount	using adjtime(2).  Otherwise, step the correction us-
	     ing settimeofday(2).  The default value is	0, which means all ad-
	     justments will be stepped.	 This is a feature, as different situ-
	     ations demand different values.

     -o	number,	--ntpversion=number
	     Send int as our NTP protocol version.  This option	takes an inte-
	     ger number	as its argument.  The value of number is constrained
	     to	being:
		 in the	range  0 through 7
	     The default number	for this option	is:
		  4

	     When sending requests to a	remote server, tell them we are	run-
	     ning NTP protocol version ntpversion .

     -r, --usereservedport
	     Use the NTP Reserved Port (port 123).

	     Use port 123, which is reserved for NTP, for our network communi-
	     cations.

     -S, --step
	     OK	to 'step' the time with	settimeofday(2).

     -s, --slew
	     OK	to 'slew' the time with	adjtime(2).

     -t	seconds, --timeout=seconds
	     The number	of seconds to wait for responses.  This	option takes
	     an	integer	number as its argument.	 The default seconds for this
	     option is:
		  5

	     When waiting for a	reply, sntp will wait the number of seconds
	     specified before giving up.  The default should be	more than
	     enough for	a unicast response.  If	sntp is	only waiting for a
	     broadcast response	a longer timeout is likely needed.

     --wait, - Fl -no-wait
	     Wait for pending replies (if not setting the time).  The no-wait
	     form will disable the option.  This option	is enabled by default.

	     If	we are not setting the time, wait for all pending responses.

     -?, --help
	     Display usage information and exit.

     -!, --more-help
	     Pass the extended usage information through a pager.

     ->	[cfgfile], --save-opts [=cfgfile]
	     Save the option state to cfgfile.	The default is the last	con-
	     figuration	file listed in the OPTION PRESETS section, below.  The
	     command will exit after updating the config file.

     -<	cfgfile, --load-opts=cfgfile, --no-load-opts
	     Load options from cfgfile.	 The no-load-opts form will disable
	     the loading of earlier config/rc/ini files.  --no-load-opts is
	     handled early, out	of order.

     --version [{v|c|n}]
	     Output version of program and exit.  The default mode is `v', a
	     simple version.  The `c' mode will	print copyright	information
	     and `n' will print	the full copyright notice.

OPTION PRESETS
     Any option	that is	not marked as not presettable may be preset by loading
     values from configuration ("RC" or	".INI")	file(s)	and values from	envi-
     ronment variables named:
       SNTP_<option-name> or SNTP
     The environmental presets take precedence (are processed later than)  the
     configuration  files.   The homerc	files are "$HOME", and ".".  If	any of
     these are directories, then the file .ntprc is searched for within	 those
     directories.

USAGE
     sntp ntpserver.somewhere
	     is	the simplest use of this program and can be run	as an unprivi-
	     leged command to check the	current	time and error in the local
	     clock.

     sntp -Ss -M 128 ntpserver.somewhere
	     With suitable privilege, run as a command or from a cron(8) job,
	     sntp -Ss -M 128 ntpserver.somewhere will request the time from
	     the server, and if	that server reports that it is synchronized
	     then if the offset	adjustment is less than	128 milliseconds the
	     correction	will be	slewed,	and if the correction is more than 128
	     milliseconds the correction  will be stepped.

     sntp -S ntpserver.somewhere
	     With suitable privilege, run as a command or from a cron(8) job,
	     sntp -S ntpserver.somewhere will set (step) the local clock from
	     a synchronized specified server, like the (deprecated)
	     ntpdate(8), or rdate(8) commands.

ENVIRONMENT
     See OPTION	PRESETS	for configuration environment variables.

FILES
     See OPTION	PRESETS	for configuration files.

EXIT STATUS
     One of the	following exit values will be returned:

     0	(EXIT_SUCCESS)
	     Successful	program	execution.

     1	(EXIT_FAILURE)
	     The operation failed or the command syntax	was not	valid.

     66	 (EX_NOINPUT)
	     A specified configuration file could not be loaded.

     70	 (EX_SOFTWARE)
	     libopts had an internal operational error.	 Please	report it to
	     autogen-users@lists.sourceforge.net.  Thank you.

AUTHORS
     Johannes Maximilian Kuehn
     Harlan Stenn
     Dave Hart

COPYRIGHT
     Copyright (C) 1992-2016 The University of Delaware	and Network Time Foun-
     dation all	rights reserved.  This program is released under the terms of
     the NTP license, <http://ntp.org/license>.

BUGS
     Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org

NOTES
     This manual page was AutoGen-erated from the sntp option definitions.

BSD				January	20 2016				   BSD

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPTION PRESETS | USAGE | ENVIRONMENT | FILES | EXIT STATUS | AUTHORS | COPYRIGHT | BUGS | NOTES

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