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ntp 4.2.6p5

    1: Notes for NTP Version 3
    2: 
    3: This version operates in much the same manner as Version 2 with the
    4: following changes and additions:
    5: 
    6: 1.   The protocol machinery operates in conformance with the RFC1305 NTP
    7:      Version 3 specification. The most visible characteristic of this
    8:      version is that the poll intervals for all polls, even selected
    9:      ones, is significantly increased. This is especially desirable when
   10:      serving a large client population. This implementation supports
   11:      previous versions as non-configured peers; for version-2 configured
   12:      peers a "version 2" keyword should be included on the "peer" line.
   13: 
   14: 2.   The configuration file has a new keyword: statfile <file>, where
   15:      <file> is the name of a statistics file." When present, each clock
   16:      update generates an entry of the form:
   17: 
   18:      <day> <sec>.<frac> <addr> <status> <offset> <delay> <disp>
   19: 
   20:      where <day> is the modified Julian day, <sec>.<frac> is the time of
   21:      day, <addr> is the peer address and <status> is the peer status.
   22:      The <offset>, <delay> and <disp> are the measured offset, delay and
   23:      dispersion, respectively, of the peer clock relative to the local
   24:      clock. About once per day the current file is closed and a new one
   25:      created with names <file>.<gen>, where <gen> starts at one and
   26:      increments for each new generation.
   27: 
   28: 3.   A number of additional platforms are supported. See ./Config file
   29:      for details.
   30: 
   31: 4.   A driver for the TrueTime 468DC GOES Synchronized Clock is
   32:      included. This driver (refclock_goes.c) should also work for other
   33:      TrueTime radio clocks, since all use the same format.
   34: 
   35: 5.   A replacement driver for the Spectracom 8170 WWVB Synchronized
   36:      Clock is included. This driver (refclock_wwvb.c) (a) does not
   37:      require a 1-pulse-per-second signal, (b) supports both format 0
   38:      (original 8170) and format 2 (Netclock/2 and upgraded 8170), (c)
   39:      can be connected to more than one computer and (d) automatically
   40:      compensates for all serial baud rates.
   41: 
   42: 6.   A driver for the German time/frequency station DCF77 is included.
   43:      This requires a special STREAMS module.
   44: 
   45: 7.   In Version 2 special line-discipline modules were required for the
   46:      CHU and WWVB drivers. This code continues to work in Version 3,
   47:      although it is no longer needed for the WWVB driver. However, this
   48:      code does not work under STREAMS, as used in SunOS 4.1.1.
   49:      Equivalent STREAMS modules are supplied with Version 3.
   50: 
   51: 8.   Support for an external 1-pulse-per-second (pps) signal is
   52:      provided. The signal is connected to a serial port (see
   53:      xntpd/ntp_loopfilter.c for details). When present the leading edge
   54:      of the pulse establishes the on-time epoch within an interval
   55:      established by the selected radio clock or other NTP time server.
   56:      Use of the pps is indicated when the tattletale displayed by ntpq
   57:      changes from "*" to "o".
   58: 
   59: 9.   The clock-selection and poll-update procedures have been modified
   60:      slightly in order to achieve better performance on high speed LANs
   61:      with compromise in performance on typical WANs.
   62: 
   63: 10.  In order to comply with U.S. Commerce Department regulations, the DES
   64:      encryption routine lib/authdes.c cannot be exported. For exportable
   65:      versions of this distribution a DES-encrypted version of this routine
   66:      lib/authdes.c.des is included along with an unencrypted version
   67:      lib/authdes.c.export, which allows normal operation, but without the
   68:      NTP authentication feature. Further information is available in the
   69:      lib/authdes.c.export file.
   70: 
   71: 11.  As an alternative to the DES-based authentication mechanism, an
   72:      implementation of the RSA Message Digest 5 algorithm is provided.
   73:      (see applicable copyright information in the library files).
   74: 
   75: 12.  A driver for the Magnavox MX4200 GPS clock.
   76: 
   77: 13.  A STREAMS module which captures carrier-detect data-lead transitions to
   78:      connect a precision source of 1-pps, yet avoid the ugly overhead in the
   79:      usual STREAMS processing. See the ppsclock subdirectory.
   80: 
   81: 14.  Support for the Apple A/UX operating system and enhanced support for the
   82:      Hewlet-Packard HP/UX operating system. See the various README and Config
   83:      files for further information. 
   84: 
   85: See the COPYRIGHT file for authors and copyright information. Note that some
   86: modules in this distribution contain copyright information that supersedes
   87: the copyright information in that file.
   88: 
   89: If I missed something or neglected to give due credit, please advise.
   90: 
   91: David L. Mills
   92: University of Delaware
   93: 31 May 1992, amended 23 July 1992, 25 October 1992
   94: 
   95: Bugs and notes
   96: 
   97: A bug in the original tty_clk_STREAMS.c module has been fixed.
   98: 
   99: The poll-interval randomization feature of poll_update (in
  100: xntpd/ntp_proto.c) has been extended to apply when the poll interval is
  101: increased, as well as reduced. This spreads the update messages in time
  102: and helps avoid unpleasant bursts of messages.
  103: 
  104: In the clock_select algorithm the peers selected for combining are
  105: limited to those survivors at the lowest stratum, not the entire list.
  106: This helps avoid whiplash when large numbers of peers are at the same
  107: stratum.
  108: 
  109: The number formerly displayed by ntpq as "compliance" is now the time
  110: constant of integration.
  111: 
  112: The DNS resolver xntpd/ntp_intres.c is now integrated into xntpd, making
  113: configuration of multiple hosts easier.
  114: 
  115: System and peer event are now written to the system log at priority
  116: LOG_INFO.
  117: 
  118: The leap-second code was fixed to avoid broadcasting leap warnings on
  119: all except the last day of June and December.