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ntp(1)								       ntp(1)



NAME

  ntp -	query a	clock running a	Network	Time Protocol daemon, either ntpd or
  xntpd

SYNOPSIS

  /usr/bin/ntp [-v] [-s] [-f] host1  | IPaddress1 ...

OPTIONS

  -v  Specifies	verbose	output.	 The output shows the full contents of the
      received NTP packets, plus the calculated	offset and delay.

  -s  Sets local clock to remote time.	This only happens if the offset
      between the local	and remote time	is less	than 1000 seconds. The local
      clock is not reset if the	remote host is unsynchronized.

      If you specify more than one host	name on	the command line, ntp queries
      each host	in order, waiting for each host	to answer or timeout before
      querying the next	host.  The local clock is set to the time of the
      first remote host	that responds.

  -f  Forces setting local clock regardless of offset.	The -f option must be
      used with	-s option.  The	local clock is not reset if the	remote host
      is unsynchronized.

DESCRIPTION

  The ntp command may be retired in a future release; use the ntpdate(8) com-
  mand instead.

  The ntp command is used to determine the offset between the local clock and
  a remote clock.  It can also be used to set the local	host's time to a
  remote host's	time.  The ntp command sends an	NTP packet to the NTP daemon
  running on each of the remote	hosts specified	on the command line. The
  remote hosts must be running either the ntpd daemon or xntpd daemon. When
  the NTP daemon on the	remote host receives the NTP packet, it	fills in the
  fields (as specified in RFC 1129), and sends the packet back.	 The ntp com-
  mand then formats and	prints the results on the standard output.

				     Note

       You can specify hosts by	either host name or Internet address.  The
       hosts that you specify must either exist	in the /etc/hosts file,	or in
       the master hosts	database, if the database is being served to your
       system by BIND or Network Information Service (NIS).

  The default output shows the roundtrip delay of the NTP packet in seconds,
  the estimated	offset between the local time and remote time in seconds, and
  the date in ctime format. See	the ctime(3) reference page for	more informa-
  tion.

  The -s and -f	options	can be used to reset the time of the local clock.






RESTRICTIONS

  Using	the -s and -f options require that you be logged on as superuser.

ERRORS

  The following	error messages can be returned by NTP:

  *Timeout*

  hostname is not responding
      May indicate that	the NTP	daemon is not running on the remote host.

  No such host:	hostname
      The NTP command cannot resolve the specified host	name in	the
      /etc/hosts file.	Check that the host exists in the /etc/hosts file, or
      that it exists in	the master hosts database, if the database is being
      served to	your system by BIND or NIS.

EXAMPLES

  In the following examples, some output text lines may	be broken. The line
  end are marked with the backslash symbol (\) and the following line is
  indented. Such text may appear as a single line on your terminal.

   1.  The following is	the default output to an ntp query about a remote
       host with an internet address of	555.5.55.5:
	    # /usr/bin/ntp 555.5.55.5
	    555.5.55.5:	delay:1.845207 offset:-0.358460	\
	     Mon Aug 20	08:05:44 1991

   2.  The following is	the verbose output to an ntp query about the same
       remote host:
	    # /usr/bin/ntp -v 555.5.55.5

	    Packet from: [555.5.55.5]
	    Leap 0, version 1, mode Server, poll 6, precision \
	     -10 stratum 1 (WWVB)
	    Synch Distance is 0000.1999	 0.099991
	    Synch Dispersion is	0000.0000  0.000000
	    Reference Timestamp	is a7bea6c3.88b40000 \
	     Tue Aug 20	14:06:43 1991
	    Originate Timestamp	is a7bea6d7.d7e6e652 \
	     Tue Aug 20	14:07:03 1991
	    Receive Timestamp is   a7bea6d7.cf1a0000 \
	     Tue Aug 20	14:07:03 1991
	    Transmit Timestamp is  a7bea6d8.0ccc0000 \
	     Tue Aug 20	14:07:04 1991
	    Input Timestamp is	   a7bea6d8.1a77e5ea \
	     Tue Aug 20	14:07:04 1991
	    555.5.55.5:	delay:0.019028 offset:-0.043890	\
	     Tue Aug 20	14:07:04 1991

       The fields are interpreted as follows:

       Packet from: [internet address]
	   The address of the remote host from which this NTP packet was
	   received.

       Leap n
	   The leap second indicator.  Non-zero	if there is to be a leap
	   second inserted in the NTP timescale.  The bits are set before
	   23:59 on the	day of insertion and reset after 00:00 on the follow-
	   ing day.

       version n
	   The NTP protocol version.

       mode type
	   The NTP mode	can be Server, Client, Symmetric Passive, Symmetric
	   Active, or Broadcast.  See RFC 1129 for more	information on NTP
	   modes.

       Poll x
	   The desired poll rate of the	peer in	seconds	as a power of 2. For
	   example, if poll is equal to	6, that	means that the poll rate is
	   one message exchanged every 2**6 seconds.

       Precision x
	   The precision of the	remote host's clock in seconds as a power of
	   2. For example, if precision	is equal to -10, that means that the
	   precision is	2**-10.	 The NTP daemon	sets this automatically.

       Stratum n (source)
	   The stratum of the clock in the NTP hierarchy, along	with the
	   source of the clock.	 The source is either the name of a reference
	   standard (such as WWVB or GOES), or the Internet address of the
	   clock that this clock references.

       Synch Distance is nn.nn nn.nn
	   The values reported are used	internally by the NTP daemon.

       Synch Dispersion	is nn.nn nn.nn
	   The values reported are used	internally by the NTP daemon.

       The next	five timestamps	are given as NTP fixed-point values, in	both
       hexadecimal and ctime. The timestamps are set either by this NTP	pro-
       cess, or	by the remote host you are querying.  These timestamps are
       used by the local host to calculate delay and offset for	this query.

       Reference Timestamp is hex-timestamp ctime_string
	   This	specifies the last time	the remote host	clock was adjusted.
	   (remote time)

       Originate Timestamp is hex-timestamp ctime_string
	   This	specifies when the NTP request was transmitted by the local
	   host	to the remote host. (local time)

       Receive Timestamp is hex-timestamp ctime_string
	   This	specifies when the NTP request was received at the remote
	   host.  (remote time)

       Transmit	Timestamp is hex-timestamp ctime_string
	   This	specifies when the NTP response	was transmitted	by the remote
	   host.  (remote time)

       Input Timestamp is hex-timestamp	ctime_string
	   This	specifies when the NTP response	was received by	the local
	   host. (local	time)

       hostname: delay:time offset:time
	   This	field summarizes the results of	the query, giving the host
	   name	or internet address of the responding clock specified in the
	   command line, the round-trip	delay in seconds, and the offset
	   between the two clocks in seconds (assuming symmetric round-trip
	   times).






SEE ALSO

  ctime(3), ntp.conf(4), ntpdate(8), xntpd(8), xntpdc(8), ntpq(8)

  Internet time	synchronization:  The Network Time Protocol (RFC 1129)

  Network Administration: Services