Network Time Protocol

The Network Time Protocol (NTP) is a protocol used to synchronize
time-of-day clocks.  NTP will continuously adjust your system's
time such that it will typically stay within a few hundredths of
a second of national time standards.  NTP places a very small
load on your processor and network, sending and receiving at
most a few packets per minute and doing minimal processing on them.

NTP service is provided by two servers on the UM campus.  It is 
intended that departmental servers will synchronize to those
servers, and in turn distribute time information to individual
machines.

NTP service to a departmental server can be enabled by sending
a message to "ntp-request@umich.edu" and providing the IP
address of the server and contact information (name, phone
number, and email address).  NOTE THAT THIS MAIL ADDRESS IS FOR
SETTING UP UMICH NTP CLIENTS ONLY.  GENERAL NTP QUESTIONS SHOULD
BE SENT TO NTP@TRANTOR.UMD.EDU.  THANK YOU FOR YOUR SUPPORT.


This directory contains four files for use with NTP:

	README			(this file)
	ntp.conf.dept		Configuration for departmental server
	ntp.conf.client		Configuration for departmental client
	xntp.tar.Z		Source for NTP daemon and utilities


The last file, xntp.tar.Z, should be retrieved (using binary mode),
uncompressed ("uncompress xntp.tar"), and untarred ("tar -xvf xntp.tar").
Tar will create the directory "xntp" in the current directory as well
as a number of subdirectories.  To build the NTP programs for SunOS 3.x,
see below.  To build programs for other systems or operating systems,
see xntp/README and xntp/Config.

Building NTP programs for Sun OS 3.x:

Move to the xntp directory, and type:
	make makefiles
and then
	make
to build the programs.  xntp/xntpd/xntpd is the NTP daemon, and should
be installed in a reasonable place (such as /etc/xntpd).

A configuration file should then be installed on /etc/ntp.conf.  Two
configuration files are supplied.  "ntp.conf.dept" should be installed
on the departmental server.  This file should be modified to contain
the broadcast IP address of the local network (as detailed in comments
within the file).

"ntp.conf.client" should be installed on each of the other machines
on the local network as /etc/ntp.conf.

The list of TCP/UDP port numbers (typically in "/etc/services") will
probably need to be updated.  NTP uses UDP port 123.  The typical
line in /etc/services will look like:
   ntp     123/udp

The daemon can be started by simply executing it from root (e.g.,
"/etc/xntpd").  It will read the configuration file from /etc/ntp.conf.
It will take approximately ten minutes to synchronize the clock the
first time, after which the clock will be within a few hundredths
of a second of standard time and will be periodically updated
thereafter.  Xntpd should typically be started from /etc/rc.local
so that time will be synchronized if the system reboots.

If contact with other time servers is lost, the local clock (having
been adjusted by NTP) will keep fairly accurate time, and will
automatically resynchronize when service is restored.

Note that the NTP daemon will exit with an error message (and not
adjust the clock) if the clock is further than 1000 seconds off (slightly
less than 17 minutes).  This should not be a problem unless the
machine has been badly hand-configured, or has been powered down and
lost its knowledge of time.


The xntp package comes with a number of utilities for configuring and
querying servers.  See the man pages in xntp/doc for more details.