readme.3.4

ftam等标准协议服务器和客户端的源代码。

README for UNIX NTP release $Date: 1992/06/16 12:42:48 $ $Revision: 9.0 $



NTP (Network Time Protocol) Daemons

	There are three programs in the NTP distribution:
	ntp	-	simple query program used for single
			sample queries

	ntpd	-	A daemon that sets up peers and responds
			to queries.  Ntpd does the clock trimming.

	ntpdc	-	program to query an ntpd.  It was useful in
			checking the filters and cleaning the windows

Installation:

	1) Add an entry to /etc/services to define the ntp port.

	ntp	123/udp		# network time protocol (exp)

	2) Make a /etc/ntp.conf with the clocks you want to track.
		Please refer to the RFC's in the man directory, the man
		pages, and the clock.txt file to assist you in selecting
		clocks to peer with.  The supplied ntp.conf is only a 
		sample, and is not suitable for use.


	3) Change the Makefile definitions to suit your environment.
	4) make
	5) make install
	6) adb or remake kernel and change "tickadj"
		Recommended values for tickadj on various machines:

		VAX:	5
		Sun3:	10
		Sun4:	5
		NeXT:	7

		This step is optional; new algorithms will allow you to
		get by (with reduced accuracy) with the system supplied
		value of tickadj.  For better preformence, you should
		change the value of tickadj.  This can be done by making
		a new kernel or by compiling ntpd with SETTICKADJ defined,
		and having ntpd set it to the value you specify.  This is
		clearly ugly.

	7) Fire up ntpd in /etc/rc.local

History:
5/17/89
	Yet another preprocessor define for broken unsigned long to double
	conversions.  Define GENERIC_UNS_BUG, and the unsigned long is shifted
	right one bit and cast to an int before conversion to a double.  This
	seems to work much better.

	Preliminary support for NeXT systems.  Be sure to define both
	GENERIC_UNS_BUG and SUN_FLT_BUG.  The default value of tickadj in the
	kernel is too large so you'll have to adjust it by using the
	-t option and compiling with SETTICKADJ.  I don't think you can use
	gdb on the running /dev/mem image.   NOTE: don't even think of trying
	to run this on the 0.8 release of the system software.  You will
	utterly and absolutely hang you system.  Current testing is being 
	done on the 0.9 release.  So far, there seems to be some weirdness in
	the kernel which is attempting to sync to the clock to the internal
	clock chip every so ofter.  So while it compiles and runs, it really
	doesn't work very well on the NeXT machine.

	Integration of the reference clock code from Doug Kingston and Jeff 
	Schiller has been done.  To configure a reference clock, check the
	ntpd manual page.

5/3/89
	The changes to the ntp_proto.c module for clockhopper suppression have
	been tweaked once more, ever so slightly to conform with the 21 April
	1989 draft of the NTP spec.  We won't switch peers if the current 
	peer makes it into the final selection list, unless the first peer on
	the selection list is of a higher stratum than the current peer.

	The ntpd.c/hourly() function now saves the value of the drift
	compensation register to a file (/etc/ntp.drift by default).  In fact,
	the last 5 hourly samples are written to the file, as well as how
	many hours the ntpd process has been running.  Ntpd will also attempt
	to intialize the value of the drift compensation register from this
	file when it is started up.  The hourly stats: log message has been
	augmented to log additional information.

4/8/89
	Changes to the ntp_proto.c module to supress peer switching when the
	dispersion between the newly selected peer and the currently selected
	peer is "small."  A new configuration option, NOSWAP, has been added
	for use on Ultrix systems which can lock the ntpd process in memory;
	very desirable for diskless workstations.  peer.reach is now not
	cleared in the clear() procedure.  The stat.pl perl script can now
	handle syslog records which span a month boundary correctly.  We're
	getting real close to a "blessed" version now.

3/29/89
	A few fixes, clean up of unused #defines in ntp.h.  The receive()
	procedure is now table driven per the 26 March 1989 draft of the
	spec.  If no terrible errors or bugs are found, this version
	will probably be packaged as a "blessed" working version before
	the next stage of major hacking.

3/22/89
	A bunch of minor fixes here an there.  The RCS header is being
	updated so that patches that are generated will apply; apparently
	the new version of RCS puts the Locked: status in the Header

	Minor fiddles to ntpd/ntpdc to eliminate some byte-sex dependencies.
	Changs to ntp_proto.c to fix an mis-interpretation in the packet
	procedure.

	The ntp program now uses connected UDP sockets to pick up ICMP
	generated errors.

	ntpdc will now select a value of tickadj if you don't specify one.

3/17/89
	Another sort-of-working ntpd.  There might still be something weird
	with the logical clock code; seems to be a little weird.  Would
	really like your comments on this version.

	Note that the a version that supports the Precision Time WWV clock
	can be had via anonymous FTP from BITSY.MIT.EDU.  The version there
	might lag the University of Maryland version.

3/12/89
	A snapshot of a more-or-less working ntpd.  There's been a few more
	bug fixes and changes due to the NTP spec being revised.  A few more
	changes have been made to the latest NTP spec (11 March 1989 version)
	which have not yet been applied.

	A few problems areas:  I currently observe some peer flapping between
	two clock which are both of very good quality (UMD1.UMD.EDU and
	TRUECHIMER.CSO.UIUC.EDU).  Not quite sure why this is happening yet
	or if it is really a problem.

	There are quite a few "Dropping peer <foo>" messages in the syslog.
	Most of these are due to lower statum "transient" clocks peering with
	the local daemon.  Need to find a way to supress the messages in
	the transmit procedure when we've got no intention of keeping a
	peer structure around for them.

	There are changes in the works to improve the reliability of the 
	ntpdc program.  The ntpd hooks are there now, and some work remains
	in the ntpdc program.


3/7/89
	*** THIS IS A TEST RELEASE ***

	This version contain most of the new algorithms from the 6 March 1989
	draft of the NTP specification.  It still operates, however, as 
	Version 1, and does not support the authentication feature.

	The stratum 1 WWV clock code from Doug Kingston has not been tested or
	changed for this release.  I would really like someone to change the
	interface to have the clock appear as just another peer.

	Quite a bit if clean-up and cosmetic changes were made in almost all
	of the modules.  Note that the ntest program which tests certain
	arithmetic operations on you machine is automatically run by the
	Makefile.  If it fail *for any reason*, stop right there and find
	out why.  Until ntest works correctly, don't even bother with the
	rest of the code.  Note that at least Ultrix has problems, and there
	is a define option in the makefile to accomodate the broken Ultrix
	pcc compiler.  Recent version of GNU CC are known to work correctly
	on a VAX platform, and is in fact used for development.  It is not
	necessary to use the GNU C compiler on you machine, however.

	The logical clock code in ntp_adjust.c has been changed to be more
	self-contained and independent from NTP proper.  It has the tickadj
	round-off residual accumulating code, and attempts to implemenet the
	newest version of the NTP logical clock code.  A large change here is
	that once an clock update has been passed to the logical clock, it will
	ignore further updated for 1<<CLOCK_UPDATE seconds.  Note that the
	units for tick_adj have changed in this version.  Eventually, a
	normalized version of this value will be written to a file for use
	on subsequent invocations.

	There has been no work in the area of supporting broadcast NTP.  A
	bunch of bug fixes have been made to the ntp_proto.c module, including
	a significant one in the code which selects the clock; the dispersion
	computed before was incorrect and resulted in poor clock choices.  This
	is probably the cause of having long "strings" of peers rather then 
	all syncing to one clock.

	The ntpd will now actually delete peer entries when the hosts "go 
	away."  This will hopefully save some memory.  The peer list is now
	doublely linked, so deletions can happen very efficiently.

	There is still a weirdness in there when interoperating with very old
	broken versions of ntpd.  It manifests itself with peers being expunged
	and them coming back.

	Please beat on this version and let me know what bugs you find.  I
	want to make another release, this one "blessed" until the Version 2
	one is ready.


1/12/89
	*** THIS IS A TEST RELEASE ***
	There have been a bunch of bug fixes, and an attemtp to unify the
	the debug output and logging.  There is still a problem with the
	verbose version of ntpdc; the offset values are clearly bogus.