Computer Time Synchronization
A Beginner's Guide to Network Time Protocol (NTP)
Warning! This Section is known to contain obsolete information.
When this section was written there was no cross platform time synchronization
software installed as part of the OS on any computer that I was aware of. Timed
would synchronize the time of Unix computers on a LAN, but not necessarily to
the correct time. Today nearly all computers come with network time synchornization
software installed. It nomally synchronizes with accurate servers on the Internet
but not with other computers on your LAN and not normally cross platform. Many
Unix like computers include a crippled version of NTP. The full version of NTP
remains the best solution for the users who want or need both accurate time
and tight synchronization of all computers on their LAN.
A tutorial on how-to install free Network
Time Protocol (NTP) servers and clients on UNIX (OpenBSD and
Linux) and Windows to synchronize the time on all your computers
to within less than a second of the official Coordinated
Universal Time (UTC). Quick start by skipping the background and
jumping to the NTP what and how. The
emphasis is on the basics of installing Network Time Protocol
servers on UNIX and Windows computers with numerous links to
detailed authoritative sources.
Other Time Software discusses
products tried before turning to Network Time Protocol. These
include UNIX's timed and NIST's free Windows clients. It's become
clear that NTP Is a Complete Solution
to the UNIX and Windows computer time synchronization and
accuracy problem. The open source Network Time Protocol server,
ntpd, is complex, and the extensive and highly technical
documentation at the official University of Delaware NTP site,
is not oriented to the practical issues of getting NTP servers to
work with a minumum of time and effort.
You can skip the previous pages but not
What NTP Does and How It Works or
Selecting Public NTP servers which
cover the minimum concepts and networking background necessary
to use NTP. Installing Network Time Protocol software is trivial
compared to figuring out what you're going to connect it to; these
pages explain the relationships between NTP servers and how to
select public servers to act as your time sources.
Installing NTP on Unix gives step
by step instructions for installing ntpd, the open source and
free Network Time Protocol server, on UNIX, specifically OpenBSD
2.6, 2.7, 2.8 and 2.9 and also Red Hat Linux 6.2 and 7.1. As the
instructions are identical they should work on any similar system
and anyone familiar with UNIX should be able to make the minor
directory adjustments that may be necessary. Minimum
configuration file contents and useable command line options are
provided and explained.
Installing NTP on Windows covers
four products. All are free, including commercial use, and one is
true open source. There are two client only products for all
Windows platforms from 95 to ME and 2000. The open source,
NetTime implements SNTP and will act as a client and or server on
all Windows platforms. Obtaining latest builds and installing
ntpd, a complete NTP implementation for Windows NT and 2000 is
covered. Ntpd runs as a service and includes both client and
server options but is configured via a text file (sorry no GUI
Choices on Other Operating Systems points
you to pages that list software for other platforms and
Conclusion offers a few final
thoughts on Network Time Protocol and ntpd, a first rate example
of open source software.
Note: Because this section now contains disclaimers that infomation
is or may be obsolete, in no way implies pages without such disclaimers are
necessarily up-to-date. Most of this site was written between 2000 and 2002.
Basics are much the same but details have changed. Information is provided as is.
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