280 lines
11 KiB
HTML
280 lines
11 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>Miscellaneous Options</title>
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</head>
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<body>
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<h3>Miscellaneous Options</h3>
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<img align="left" src="pic/boom3.gif" alt="gif"><a href=
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"http://www.eecis.udel.edu/~mills/pictures.htm">from <i>Pogo</i>,
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Walt Kelly</a>
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<p>We have three, now looking for more.<br clear="left">
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</p>
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<hr>
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<dl>
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<dt><tt>broadcastdelay <i>seconds</i></tt></dt>
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<dd>The broadcast and multicast modes require a special calibration
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to determine the network delay between the local and remote
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servers. Ordinarily, this is done automatically by the initial
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protocol exchanges between the client and server. In some cases,
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the calibration procedure may fail due to network or server access
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controls, for example. This command specifies the default delay to
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be used under these circumstances. Typically (for Ethernet), a
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number between 0.003 and 0.007 seconds is appropriate. The default
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when this command is not used is 0.004 seconds.</dd>
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<dt><tt>driftfile <i>driftfile</i></tt></dt>
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<dd>This command specifies the name of the file used to record the
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frequency offset of the local clock oscillator. If the file exists,
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it is read at startup in order to set the initial frequency offset
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and then updated once per hour with the current frequency offset
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computed by the daemon. If the file does not exist or this command
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is not given, the initial frequency offset is assumed zero. In this
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case, it may take some hours for the frequency to stabilize and the
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residual timing errors to subside.
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<p>The file format consists of a single line containing a single
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floating point number, which records the frequency offset measured
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in parts-per-million (PPM). The file is updated by first writing
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the current drift value into a temporary file and then renaming
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this file to replace the old version. This implies that <tt>
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ntpd</tt> must have write permission for the directory the drift
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file is located in, and that file system links, symbolic or
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otherwise, should be avoided.</p>
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</dd>
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<dt><tt>enable [auth | bclient | calibrate | kernel | monitor | ntp
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| stats]</tt><br>
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<tt>disable [auth | bclient | calibrate | kernel | monitor | ntp |
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stats</tt></dt>
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<dd>Provides a way to enable or disable various server options.
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Flags not mentioned are unaffected. Note that all of these flags
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can be controlled remotely using the <a href="ntpdc.htm"><tt>
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ntpdc</tt></a> utility program.</dd>
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<dd>
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<dl>
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<dt><tt>bclient</tt></dt>
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<dd>When enabled, this is identical to the <tt>broadcastclient</tt>
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command. The default for this flag is <tt>disable</tt>.</dd>
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<dt><tt>calibrate</tt></dt>
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<dd>Enables the calibration facility, which automatically adjusts
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the <tt>time1</tt> values for each clock driver to display the same
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offset as the currently selected source or kernel discipline
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signal. See the <a href="refclock.htm">Reference Clock Drivers</a>
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for further information. The default for this flag is <tt>
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disable</tt>.</dd>
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<dt><tt>kernel</tt></dt>
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<dd>Enables the precision-time kernel support for the <tt>
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ntp_adjtime()</tt> system call, if implemented. Ordinarily, support
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for this routine is detected automatically when the NTP daemon is
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compiled, so it is not necessary for the user to worry about this
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flag. It flag is provided primarily so that this support can be
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disabled during kernel development. The default for this flag is
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<tt>enable</tt>.</dd>
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<dt><tt>monitor</tt></dt>
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<dd>Enables the monitoring facility. See the <tt>ntpdc</tt> program
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and the <tt>monlist</tt> command or further information. The
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default for this flag is <tt>enable</tt>.</dd>
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<dt><tt>ntp</tt></dt>
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<dd>Enables the server to adjust its local clock by means of NTP.
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If disabled, the local clock free-runs at its intrinsic time and
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frequency offset. This flag is useful in case the local clock is
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controlled by some other device or protocol and NTP is used only to
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provide synchronization to other clients. In this case, the local
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clock driver can be used to provide this function and also certain
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time variables for error estimates and leap-indicators. See the <a
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href="refclock.htm">Reference Clock Drivers</a> page for further
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information. The default for this flag is <tt>enable</tt>.</dd>
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<dt><tt>stats</tt></dt>
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<dd>Enables the statistics facility. See the <a href="monopt.htm">
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Monitoring Options</a> page for further information. The default
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for this flag is <tt>enable</tt>.</dd>
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</dl>
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</dd>
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<dt><tt>logconfig <i>configkeyword</i></tt></dt>
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<dd>This command controls the amount and type of output written to
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the system <tt>syslog</tt> facility or the alternate <tt>
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logfile</tt> log file. By default, all output is turned on. All <i>
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<tt>configkeyword</tt></i> keywords can be prefixed with <tt>
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=</tt>, <tt>+</tt> and <tt>-</tt>, where <tt>=</tt> sets the <tt>
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syslogmask</tt>, <tt>+</tt> adds and <tt>-</tt> removes messages.
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<tt>syslog messages</tt> can be controlled in four classes
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(<tt>clock</tt>, <tt>peer</tt>, <tt>sys</tt> and <tt>sync</tt>).
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Within these classes four types of messages can be controlled.</dd>
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<dd>Informational messages (<tt>info</tt>) control configuration
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information. Event messages (<tt>events</tt>) control logging of
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events (reachability, synchronization, alarm conditions).
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Statistical output is controlled with the <tt>statistics</tt>
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keyword. The final message group is the status messages. This
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describes mainly the synchronizations status. Configuration
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keywords are formed by concatenating the message class with the
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event class. The <tt>all</tt> prefix can be used instead of a
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message class. A message class may also be followed by the <tt>
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all</tt> keyword to enable/disable all messages of the respective
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message class.</dd>
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<dd>Thus, a minimal log configuration could look like this:
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<p><tt>logconfig=syncstatus +sysevents</tt></p>
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<p>This would just list the synchronizations state of <tt>ntpd</tt>
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and the major system events. For a simple reference server, the
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following minimum message configuration could be useful:</p>
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<p><tt>logconfig=syncall +clockall</tt></p>
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<p>This configuration will list all clock information and
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synchronization information. All other events and messages about
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peers, system events and so on is suppressed.</p>
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</dd>
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<dt><tt>logfile <i>logfile</i></tt></dt>
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<dd>This command specifies the location of an alternate log file to
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be used instead of the default system <tt>syslog</tt>
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facility.</dd>
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<dt><tt>setvar <i>variable</i> [default]</tt></dt>
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<dd>This command adds an additional system variable. These
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variables can be used to distribute additional information such as
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the access policy. If the variable of the form <tt><i>name</i> =
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<i>value</i></tt> is followed by the <tt>default</tt> keyword, the
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variable will be listed as part of the default system variables
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(<tt>ntpq rv</tt> command). These additional variables serve
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informational purposes only. They are not related to the protocol
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other that they can be listed. The known protocol variables will
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always override any variables defined via the <tt>setvar</tt>
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mechanism. There are three special variables that contain the names
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of all variable of the same group. The <tt>sys_var_list</tt> holds
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the names of all system variables. The <tt>peer_var_list</tt> holds
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the names of all peer variables and the <tt>clock_var_list</tt>
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holds the names of the reference clock variables.</dd>
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<dt><tt>tinker [ step <i>step</i> | panic <i>panic</i> | dispersion
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<i>dispersion</i> | stepout <i>stepout</i> | minpoll <i>minpoll</i>
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]</tt></dt>
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<dd>This command can be used to alter several system variables in
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very exceptional circumstances. It should occur in the
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configuration file before any other configuration options. The
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default values of these variables have been carefully optimized for
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a wide range of network speeds and reliability expectations. In
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general, they interact in intricate ways that are hard to predict
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and some combinations can result in some very nasty behavior. Very
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rarely is it necessary to change the default values; but, some
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folks can't resist twisting the knobs anyway and this command is
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for them. Emphasis added: twisters are on their own and can expect
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no help from the support group.
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<p>All arguments are in floating point seconds or seconds per
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second. The <tt>minpoll</tt> argument is an integer in seconds to
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the power of two. The variables operate as follows:</p>
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</dd>
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<dd>
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<dl>
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<dt><tt>step <i>step</i></tt></dt>
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<dd>The argument becomes the new value for the step threshold,
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normally 0.128 s. If set to zero, step adjustments will never
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occur. In general, if the intent is only to avoid step adjustments,
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the step threshold should be left alone and the <tt>-x</tt> command
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line option be used instead.</dd>
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<dt><tt>panic <i>panic</i></tt></dt>
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<dd>The argument becomes the new value for the panic threshold,
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normally 1000 s. If set to zero, the panic sanity check is disabled
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and a clock offset of any value will be accepted.</dd>
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<dt><tt>dispersion <i>dispersion</i></tt></dt>
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<dd>The argument becomes the new value for the dispersion increase
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rate, normally .000015.</dd>
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<dt><tt>stepout <i>stepout</i></tt></dt>
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<dd>The argument becomes the new value for the watchdog timeout,
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normally 900 s.</dd>
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<dt><tt>minpoll <i>minpoll</i></tt></dt>
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<dd>The argument becomes the new value for the minimum poll
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interval used when configuring multicast client, manycast client
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and , symmetric passive mode association. The value defaults to 6
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(64 s) and has a lower limit of 4 (16 s).</dd>
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<dt><tt>allan <i>allan</i></tt></dt>
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<dd>The argument becomes the new value for the minimum Allan
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intercept, which is a parameter of the PLL/FLL clock discipline
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algorithm. The value defaults to 1024 s, which is also the lower
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limit.</dd>
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<dt><tt>huffpuff <i>huffpuff</i></tt></dt>
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<dd>The argument becomes the new value for the experimental
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huff-n'-puff filter span, which determines the most recent interval
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the algorithm will search for a minimum delay. The lower limit is
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900 s (15 m), but a more reasonable value is 7200 (2 hours). There
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is no default, since the filter is not enabled unless this command
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is given.</dd>
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</dl>
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</dd>
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<dt><tt>trap <i>host_address</i> [port <i>port_number</i>]
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[interface <i>interface_address</i>]</tt></dt>
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<dd>This command configures a trap receiver at the given host
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address and port number for sending messages with the specified
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local interface address. If the port number is unspecified, a value
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of 18447 is used. If the interface address is not specified, the
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message is sent with a source address of the local interface the
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message is sent through. Note that on a multihomed host the
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interface used may vary from time to time with routing changes.
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<p>The trap receiver will generally log event messages and other
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information from the server in a log file. While such monitor
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programs may also request their own trap dynamically, configuring a
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trap receiver will ensure that no messages are lost when the server
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is started.</p>
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</dd>
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</dl>
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<h4>Files</h4>
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<tt>ntp.drift</tt> frequency compensation (PPM)
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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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