101 lines
4.3 KiB
HTML
101 lines
4.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
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<html>
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<head>
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<title>Quick Start</title>
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</head>
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<body>
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<h3>Quick Start</h3>
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<img align="left" src="pic/panda.gif" alt="gif">FAX test image for
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SATNET (1979).
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<p>The baby panda was scanned at University College London and used
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as a FAX test image for a demonstration of the DARPA Atlantic
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SATNET Program and the first transatlantic Internet connection in
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1978. The computing system used for that demonstration was called
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the <a href=
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"http://www.eecis.udel.edu/~mills/database/papers/fuzz.ps">
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Fuzzball</a> . As it happened, this was also the first Internet
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multimedia presentation and the first to use NTP in regular
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operation. The image was widely copied and used for testing purpose
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throughout much of the 1980s.<br clear="left">
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</p>
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<hr>
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<p>For the rank amateur the sheer volume of the documentation
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collection must be intimidating. However, it doesn't take much to
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fly the <tt>ntpd</tt> daemon with a simple configuration where a
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workstation needs to synchronize to some server elsewhere in the
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Internet. The first thing that needs to be done is to build the
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distribution for the particular workstation and install in the
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usual place. The <a href="build.htm">Building and Installing the
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Distribution</a> page describes how to do this.</p>
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<p>While it is possible that certain configurations do not need a
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configuration file, most do require one. Strictly speaking, the
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file need only contain one line specifying a remote server, for
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instance</p>
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<p><tt>server foo.bar.com</tt></p>
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<p>Choosing an appropriate remote server is somewhat of a black
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art, but a suboptimal choice is seldom a problem. Links to public
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time servers operated by National Institutes of Science and
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Technology (NIST), US Naval Observatory (USNO), Canadian Metrology
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Centre (CMC) and many others are given in the home page of this
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document collection. The lists are sorted by country and, in the
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case of the US, by state. Usually, the best choice is the nearest
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in geographical terms, but the terms of engagement specified in
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each list entry should be carefully respected.</p>
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<p>During operation <tt>ntpd</tt> measures and corrects for
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incidental clock frequency error and writes the current value to a
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file if enabled. If the <tt>ntpd</tt> is stopped and restarted, it
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initializes the frequency from this file. In this way the
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potentially lengthy interval to relearn the frequency error is
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avoided. Thus, for most applications an additional line should be
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added to the file of the form</p>
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<p><tt>driftfile /etc/ntp.drift</tt></p>
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<p>That's all there is to it, unless some problem in network
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connectivity or local operating system configuration occurs. The
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most common problem is some firewall between the workstation and
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server. System administrators should understand NTP uses UDP port
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123 as both the source and destination port and that NTP does not
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involve any operating system interaction other than to set the
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system clock. While almost all modern Unix systems have included
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NTP and UDP port 123 defined in the services file, this should be
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checked if <tt>ntpd</tt> fails to come up at all.</p>
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<p>The best way to confirm NTP is working is using the <a href=
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"ntpq.htm"><tt>ntpq</tt></a> utility, although the <a href=
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"ntpdc.htm"><tt>ntpdc</tt></a> utility may be useful in extreme
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cases. See the documentation pages for further information. In the
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most extreme cases the <tt>-d</tt> option on the <tt>ntpd</tt>
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command line results in a blow-by-blow trace of the daemon
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operations. While the trace output can be cryptic, to say the
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least, it gives a general idea of what the program is doing and, in
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particular, details the arriving and departing packets and detected
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errors, if present.</p>
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<p>Sometimes the <tt>ntpd</tt>. behavior may seem to violate the
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Principle of Least Astonishment, but there are good reasons for
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this. See the <a href="ntpd.htm">Network Time Protocol (NTP)
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daemon</a> page for revealing insights. See this page and its
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dependencies for additional configuration and control options. The
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<a href="notes.htm">Notes on Configuring NTP and Setting up a NTP
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Subnet</a> page contains an extended discussion of these
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options.</p>
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<hr>
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<a href="index.htm"><img align="left" src="pic/home.gif" alt=
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"gif"></a>
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<address><a href="mailto:mills@udel.edu">David L. Mills
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<mills@udel.edu></a></address>
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</body>
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</html>
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