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diff --git a/html/index.htm b/html/index.htm new file mode 100644 index 000000000000..680cec80572c --- /dev/null +++ b/html/index.htm @@ -0,0 +1,261 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> +<head> +<meta name="generator" content="HTML Tidy, see www.w3.org"> +<title>The Network Time Protocol (NTP) Distribution</title> +</head> +<body> +<h3>The Network Time Protocol (NTP) Distribution</h3> + +<img align="left" src="pic/barnstable.gif" alt="gif"><a href= +"http://www.eecis.udel.edu/~mills/pictures.htm"><i>P.T. Bridgeport +Bear</i>; from <i>Pogo</i>, Walt Kelly</a> + +<p>Pleased to meet you.<br clear="left"> +</p> + +<hr> +<h4>Introduction</h4> + +Note: The software contained in this distribution is available +without charge under the conditions set forth in the <a href= +"copyright.htm">Copyright Notice</a>. + +<p>The Network Time Protocol (NTP) is used to synchronize the time +of a computer client or server to another server or reference time +source, such as a radio or satellite receiver or modem. It provides +accuracies typically within a millisecond on LANs and up to a few +tens of milliseconds on WANs relative to Coordinated Universal Time +(UTC) via a Global Positioning Service (GPS) receiver, for example. +Typical NTP configurations utilize multiple redundant servers and +diverse network paths in order to achieve high accuracy and +reliability. Some configurations include cryptographic +authentication to prevent accidental or malicious protocol attacks +and some provide automatic server discovery using IP multicast.</p> + +<p>Background information on computer network time synchronization +can be found on the <a href="exec.htm">Executive Summary - Computer +Network Time Synchronization</a> page. Discussion on protocol +conformance issues and interoperability with previous NTP versions +can be found in the <a href="biblio.htm">Protocol Conformance +Statement</a> page. Discussion on how NTP reckons the time can be +found in the <a href="leap.htm">NTP Timescale and Leap Seconds</a> +page. Background information, bibliography and briefing slides +suitable for presentations can be found in the <a href= +"http://www.eecis.udel.edu/~mills/ntp.htm">Network Time +Synchronization Project</a> page. Additional information can be +found at the NTP web site <a href="http://www.ntp.org"> +www.ntp.org</a>. Please send bug reports to <a href= +"mailto:bugs@mail.ntp.org"><bugs@mail.ntp.org></a>.</p> + +<h4>Building and Installing NTP</h4> + +NTP supports Unix and Windows (NT4 and 2000) systems. The <a href= +"build.htm">Building and Installing the Distribution</a> page +presents an overview of the procedures for compiling the +distribution and installing it on a typical client or server. The +build procedures inspect the system hardware and software +environment and automatically select the appropriate options for +that environment. While these procedures work with most computers +and operating systems marketed today, exceptions requiring manual +intervention do exist, as documented in the <a href="config.htm"> +Configuration Options</a> and <a href="release.htm">Release +Notes</a> pages. Note that support for strong cryptography requires +cryptographic libraries not included in this distribution. + +<p>Bringing up a NTP primary server requires a radio or satellite +receiver or modem. It is also possible to configure a machine on an +isolated network with the local clock driver and have other +machines synchronize to it. The distribution includes hardware +drivers for the local clock and over three dozen radio clocks and +modem services. A list of supported drivers is given in the <a +href="refclock.htm">Reference Clock Drivers</a> page. For most +popular workstations marketed by Digital/Compaq, Sun and Hewlett +Packard, as well as widely available Unix clones such as FreeBSD +and Linux, the automatic build procedures select all drivers that +run on the target machine. While this increases the size of the +executable binary somewhat, individual drivers can be included or +excluded using the configure utility documented in the +Configuration Options page.</p> + +<h4>Configuring Clients and Servers</h4> + +<p>NTP is by its very nature a complex distributed network +application and can be configured and used for a great many widely +divergent timekeeping scenarios. The documentation presented on +these pages attempts to cover the entire suite of configuration, +operation and maintenance facilities which this distribution +supports. However, most applications will need only a few of these +facilities. If this is the case, the <a href="quick.htm">Quick +Start</a> page may be useful to get a simple workstation on the air +with an existing server.</p> + +<p>However, in order to participate in the existing NTP +synchronization subnet and obtain accurate, reliable time, it is +usually necessary to construct an appropriate configuration file, +commonly called <tt>ntp.conf</tt>, which establishes the servers +and/or external receivers or modems to be used by this particular +machine. Directions for constructing this file are in the <a href= +"notes.htm">Notes on Configuring NTP and Setting up a NTP +Subnet</a> page. However, in many common cases involving simple +network topologies and workstations, the configuration data can be +specified entirely on the command line for the <a href="ntpd.htm"> +<tt>ntpd</tt> - Network Time Protocol (NTP) daemon</a>.</p> + +<p>The most important factor in providing accurate, reliable time +is the selection of modes and servers to be used in the +configuration file. A discussion on the available modes is on the +<a href="assoc.htm">Association Management</a> page. NTP support +for one or more computers is normally engineered as part of the +existing NTP synchronization subnet. The existing NTP subnet +consists of a multiply redundant hierarchy of servers and clients, +with each level in the hierarchy identified by stratum number. +Primary servers operate at stratum one and provide synchronization +to secondary servers operating at stratum two and so on to higher +strata. In this hierarchy, clients are simply servers that have no +dependents.</p> + +<p>The NTP subnet in late 2000 includes over a hundred public +primary (stratum 1) servers synchronized directly to UTC by radio, +satellite or modem and located in every continent of the globe, +including Antarctica. Normally, client workstations and servers +with a relatively small number of clients do not synchronize to +primary servers. There are over a hundred public secondary (stratum +2) servers synchronized to the primary servers and providing +synchronization to a total in excess of 100,000 clients and servers +in the Internet. The current lists are maintained in the <a href= +"http://www.eecis.udel.edu/~mills/ntp/index.htm">Information on +Time and Frequency Services</a> page, which is updated frequently. +There are numerous private primary and secondary servers not +normally available to the public as well. You are strongly +discouraged from using these servers, since they sometimes hide in +little ghettos behind dinky links to the outside world and your +traffic can bring up expensive ISDN lines, causing much grief and +frustration.</p> + +<h4>Resolving Problems</h4> + +Like other things Internet, the NTP synchronization subnets tend to +be large and devilishly intricate, with many opportunities for +misconfiguration and network problems. The NTP engineering model is +specifically designed to help isolate and repair such problems +using an integrated management protocol, together with a suite of +monitoring and debugging tools. There is an optional data recording +facility which can be used to record normal and aberrant operation, +log problems to the system log facility, and retain records of +client access. The <a href="debug.htm">NTP Debugging Techniques</a> +and <a href="hints.htm">Hints and Kinks</a> pages contain useful +information for identifying problems and devising solutions. + +<p>Users are requested to report bugs, offer suggestions and +contribute additions to this distribution. The <a href= +"patches.htm">Patching Procedures</a> page suggests procedures +which greatly simplify distribution updates, while the <a href= +"porting.htm">Porting Hints</a> page suggest ways to make porting +this code to new hardware and operating systems easier. Additional +information on reference clock driver construction and debugging +can be found in the <a href="refclock.htm">Reference Clock +Drivers</a> page. Further information on NTP in the Internet can be +found in the <a href="http://www.eecis.udel.edu/~ntp">NTP web +page</a>.</p> + +<h4>Program Manual Pages</h4> + +<ul> +<li><a href="ntpd.htm"><tt>ntpd</tt> - Network Time Protocol (NTP) +daemon</a></li> + +<li><a href="ntpq.htm"><tt>ntpq</tt> - standard NTP query +program</a></li> + +<li><a href="ntpdc.htm"><tt>ntpdc</tt> - special NTP query +program</a></li> + +<li><a href="ntpdate.htm"><tt>ntpdate</tt> - set the date and time +via NTP</a></li> + +<li><a href="ntptrace.htm"><tt>ntptrace</tt> - trace a chain of NTP +servers back to the primary source</a></li> + +<li><a href="tickadj.htm"><tt>tickadj</tt> - set time-related +kernel variables</a></li> + +<li><a href="ntptime.htm"><tt>ntptime</tt> - read kernel time +variables</a></li> + +<li><a href="genkeys.htm"><tt>ntp-genkeys</tt> - generate public +and private keys</a></li> +</ul> + +<h4>Supporting Documentation</h4> + +<ul> +<li><a href="http://www.eecis.udel.edu/~mills/ntp.htm">NTP Project +and Reference Library</a></li> + +<li><a href="copyright.htm">Copyright Notice</a></li> + +<li><a href="exec.htm">Executive Summary - Computer Network Time +Synchronization</a></li> + +<li><a href="biblio.htm">Protocol Conformance Statement</a></li> + +<li><a href="leap.htm">NTP Timescale and Leap Seconds</a></li> + +<li><a href="notes.htm">Notes on Configuring NTP and Setting up a +NTP Subnet</a></li> + +<li><a href="release.htm">NTP Version 4 Release Notes</a></li> + +<li><a href="build.htm">Building and Installing the +Distribution</a></li> + +<li><a href="config.htm">Configuration Options</a></li> + +<li><a href="debug.htm">NTP Debugging Techniques</a></li> + +<li><a href="refclock.htm">Reference Clock Drivers</a></li> + +<li><a href="patches.htm">Patching Procedures</a></li> + +<li><a href="hints.htm">Hints and Kinks</a></li> + +<li><a href="porting.htm">Porting Hints</a></li> +</ul> + +<h4>Application Notes</h4> + +<ul> +<li><a href="prefer.htm">Mitigation Rules and the <tt>prefer</tt> +Keyword</a></li> + +<li><a href="assoc.htm">Association Management</a></li> + +<li><a href="pps.htm">Pulse-per-second (PPS) Signal +Interfacing</a></li> + +<li><a href="gadget.htm">Gadget Box PPS Level Converter and CHU +Modem</a></li> + +<li><a href="measure.htm">Time and Time Interval Measurement with +Application to Computer and Network Performance Evaluation</a></li> + +<li><a href="kern.htm">Kernel Model for Precision +Timekeeping</a></li> + +<li><a href="kernpps.htm">Kernel Programming Interface for +Precision Time Signals</a></li> +</ul> + +<hr> +<center><img src="pic/pogo1a.gif" alt="gif"></center> + +<br> +<a href="index.htm"><img align="left" src="pic/home.gif" alt= +"gif"></a> + +<address><a href="mailto:mills@udel.edu">David L. Mills +<mills@udel.edu></a></address> +</body> +</html> + |