Notes for NTP Version 3This version operates in much the same manner as Version 2 with thefollowing changes and additions:1.   The protocol machinery operates in conformance with the RFC1305 NTP     Version 3 specification. The most visible characteristic of this     version is that the poll intervals for all polls, even selected     ones, is significantly increased. This is especially desirable when     serving a large client population. This implementation supports     previous versions as non-configured peers; for version-2 configured     peers a "version 2" keyword should be included on the "peer" line.2.   The configuration file has a new keyword: statfile <file>, where     <file> is the name of a statistics file." When present, each clock     update generates an entry of the form:     <day> <sec>.<frac> <addr> <status> <offset> <delay> <disp>     where <day> is the modified Julian day, <sec>.<frac> is the time of     day, <addr> is the peer address and <status> is the peer status.     The <offset>, <delay> and <disp> are the measured offset, delay and     dispersion, respectively, of the peer clock relative to the local     clock. About once per day the current file is closed and a new one     created with names <file>.<gen>, where <gen> starts at one and     increments for each new generation.3.   A number of additional platforms are supported. See ./Config file     for details.4.   A driver for the TrueTime 468DC GOES Synchronized Clock is     included. This driver (refclock_goes.c) should also work for other     TrueTime radio clocks, since all use the same format.5.   A replacement driver for the Spectracom 8170 WWVB Synchronized     Clock is included. This driver (refclock_wwvb.c) (a) does not     require a 1-pulse-per-second signal, (b) supports both format 0     (original 8170) and format 2 (Netclock/2 and upgraded 8170), (c)     can be connected to more than one computer and (d) automatically     compensates for all serial baud rates.6.   A driver for the German time/frequency station DCF77 is included.     This requires a special STREAMS module.7.   In Version 2 special line-discipline modules were required for the     CHU and WWVB drivers. This code continues to work in Version 3,     although it is no longer needed for the WWVB driver. However, this     code does not work under STREAMS, as used in SunOS 4.1.1.     Equivalent STREAMS modules are supplied with Version 3.8.   Support for an external 1-pulse-per-second (pps) signal is     provided. The signal is connected to a serial port (see     xntpd/ntp_loopfilter.c for details). When present the leading edge     of the pulse establishes the on-time epoch within an interval     established by the selected radio clock or other NTP time server.     Use of the pps is indicated when the tattletale displayed by ntpq     changes from "*" to "o".9.   The clock-selection and poll-update procedures have been modified     slightly in order to achieve better performance on high speed LANs     with compromise in performance on typical WANs.10.  In order to comply with U.S. Commerce Department regulations, the DES     encryption routine lib/authdes.c cannot be exported. For exportable     versions of this distribution a DES-encrypted version of this routine     lib/authdes.c.des is included along with an unencrypted version     lib/authdes.c.export, which allows normal operation, but without the     NTP authentication feature. Further information is available in the     lib/authdes.c.export file.11.  As an alternative to the DES-based authentication mechanism, an     implementation of the RSA Message Digest 5 algorithm is provided.     (see applicable copyright information in the library files).12.  A driver for the Magnavox MX4200 GPS clock.13.  A STREAMS module which captures carrier-detect data-lead transitions to     connect a precision source of 1-pps, yet avoid the ugly overhead in the     usual STREAMS processing. See the ppsclock subdirectory.14.  Support for the Apple A/UX operating system and enhanced support for the     Hewlet-Packard HP/UX operating system. See the various README and Config     files for further information. See the COPYRIGHT file for authors and copyright information. Note that somemodules in this distribution contain copyright information that supersedesthe copyright information in that file.If I missed something or neglected to give due credit, please advise.David L. MillsUniversity of Delaware31 May 1992, amended 23 July 1992, 25 October 1992Bugs and notesA bug in the original tty_clk_STREAMS.c module has been fixed.The poll-interval randomization feature of poll_update (inxntpd/ntp_proto.c) has been extended to apply when the poll interval isincreased, as well as reduced. This spreads the update messages in timeand helps avoid unpleasant bursts of messages.In the clock_select algorithm the peers selected for combining arelimited to those survivors at the lowest stratum, not the entire list.This helps avoid whiplash when large numbers of peers are at the samestratum.The number formerly displayed by ntpq as "compliance" is now the timeconstant of integration.The DNS resolver xntpd/ntp_intres.c is now integrated into xntpd, makingconfiguration of multiple hosts easier.System and peer event are now written to the system log at priorityLOG_INFO.The leap-second code was fixed to avoid broadcasting leap warnings onall except the last day of June and December.