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Real Time Estimation and Prediction Using Optimistic Simulation and Control Theory Te
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NTP(8) System Manager's Manual NTP(8) NAME
ntp - query an ntp clock SYNOPSIS
ntp [-v] [-s] [-f] hosts... DESCRIPTION
ntp sends an ntp packet to the ntp daemon running on each of the given hosts. A daemon fills in fields of the ntp packet as per RFC-???? and sends the packet back. ntp then formats and prints the result on the standard output. The default output shows the delay, offset, and date in ctime() format. Options can reset the time of the local system clock. OPTIONS
-v Verbose output, showing the full contents of received ntp packets, plus caluclated offset, displacement, etc. -s Set system time-of-day clock. Will only happen if time offset is less than compiled-in constant WAYTOBIG (currently 1000 seconds). Will not happen if remote host is unsynchronized. -f Force setting system clock regardless of offset. Must be used with -s option. Still will not reset clock if remote system is unsynchronized. NTP RESULTS
The default output for each host looks like this: 128.8.10.1: delay:1.845207 offset:-0.358460 Mon Mar 20 08:05:44 1989 The verbose output for each host looks like this: Packet from: [128.8.10.1] 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 Mar 7 14:06:43 1989 Originate Timestamp is a7bea6d7.d7e6e652 Tue Mar 7 14:07:03 1989 Receive Timestamp is a7bea6d7.cf1a0000 Tue Mar 7 14:07:03 1989 Transmit Timestamp is a7bea6d8.0ccc0000 Tue Mar 7 14:07:04 1989 Input Timestamp is a7bea6d8.1a77e5ea Tue Mar 7 14:07:04 1989 umd1: delay:0.019028 offset:-0.043890 Tue Mar 7 14:07:04 1989 The various fields are interpreted as follows: Packet from: [address] The address that this ntp packet was received from. Leap indicator: n The leap second indicator. Non-zero if there is to be a leap second added or subtracted at the new year. Status: n Stratum: n (source) The stratum of the clock in the NTP hierarchy, along with the source of the clock, either the name of a reference standard (such as WWVB or GOES) or the Internet address of the clock that this clock is derived from. Poll = n The desired poll rate of the peer. Precision = exponent (dec) The claimed precision of the clock, in seconds. Synchronizing Dist is ??? Synchronizing Dispersion is ??? The next five timestamps are given as NTP fixed-point values, in both hexadecimal and ctime(3). These are set either by this ntp process, or by the server we are quering. Reference Timestamp is hex-timestamp ctime string The last time the server clock was adjusted. (remote time) Originate Timestamp is hex-timestamp ctime string When the ntp request was transmitted by us to the server. (local time) Receive Timestamp is hex-timestamp ctime string When the ntp request was received at the server. (remote time) Transmit Timestamp is hex-timestamp ctime string When the ntp response was transmitted by the server. (remote time) Input Timestamp is hex-timestamp ctime string When the ntp response was received by us. (local time) hostname: delay:time offset:time The summary of the results of the query, giving the hostname of the responding clock (from the command line), the round-trip delay, and the offset between the two clocks (assuming symmetric round-trip times). BUGS
Using ntp with the current host will show inaccurate results. Probably a few others. Report bugs to Louis A. Mamokos (louie@trantor.umd.edu). SEE ALSO
RFC-???? Network Time Protocol(1), Dave Mills and ... ntpd(8), ntpdc(8) 30 July 1988 NTP(8)
