191 lines
8.8 KiB
HTML
191 lines
8.8 KiB
HTML
<!-- $NetBSD: confopt.html,v 1.1 1998/12/30 20:20:33 mcr Exp $ -->
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Strict//EN">
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<html><head><title>
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Configuration Options
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</title></head><body><h3>
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Configuration Options
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</h3><hr>
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<p><h4>Configuration Commands</h4>
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<dl>
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<dt><code>peer <i>address</i> [ key <i>key</i> ] [ version
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<i>version</i> ] [ prefer ]</code> [ minpoll <i>minpoll</i> [ maxpoll
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<i>maxpoll</i> ]
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<br><code>server <i>address</i> [ key <i>key</i> ] [ version
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<i>version</i> ] [ prefer ] [ mode <i>mode</i> ]</code>
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<br><code>broadcast <i>address</i> [ key <i>key</i> ] [ version
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<i>version</i> ] [ ttl <i>ttl</i> ]</code>
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<dd>These three commands specify the time server name or address
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<i>address</i> to be used and the mode in which to operate. The
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<i>address</i> can be either a DNS name or a IP address in dotted-quad
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notation. The <code>peer</code> command specifies that the local server
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is to operate in symmetric active mode with the remote server. In this
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mode, the local server can be synchronized to the remote server and, in
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addition, the remote server can be synchronized by the local server.
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This is useful in a network of servers where, depending on various
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failure scenarios, either the local or remote server may be the better
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source of time.
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<p><dd>The <code>server</code> command specifies that the local server
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is to operate in client mode with the specified remote server. In this
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mode, the local server can be synchronized to the remote server, but the
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remote server can never be synchronized to the local server.
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<p><dd>The <code>broadcast</code> command specifies that the local
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server is to operate in broadcast mode, where the local server sends
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periodic broadcast messages to a client population at the
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broadcast/multicast <i>address</i> specified. Ordinarily, this
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specification applies only to the local server operating as a sender;
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for operation as a broadcast client, see the
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<code>broadcastclient</code> or <code>multicastclient</code> commands
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below. In this mode, <i>address</i> is usually the broadcast address on
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(one of) the local network(s) or a multicast address assigned to NTP.
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The Numbers Czar has assigned the address 224.0.1.1 to NTP; this is
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presently the only address that should be used. Note that the use of
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multicast features requires a multicast kernel, which is not yet
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ubiquitous in vendor products.
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<p><dd>Options
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<dl>
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<dt><code>key <i>key</i></code>
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<dd>All packets sent to the address are to include authentication fields
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encrypted using the specified <i>key</i> identifier, which is an
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unsigned 32 bit integer. The default is to not include an encryption
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field.
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<p><dt><code>version <i>version</i></code>
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<dd>Specifies the version number to be used for outgoing NTP packets.
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Versions 1, 2, and 3 are the choices, with version 3 the default.
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<p><dt><code>prefer</code>
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<dd>Marks the server as preferred. All other things being equal, this
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host will be chosen for synchronization among a set of correctly
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operating hosts. See the <a href = "prefer.html"> Mitigation Rules and
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the <code>prefer</code> Keyword </a> page for further information.
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<p><dt><code>ttl <i>ttl</i></code>
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<dd>This option is used only with broadcast mode. It specifies the time-
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to-live <i>ttl</i> to use on multicast packets. Selection of the proper
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value, which defaults to 127, is something of a black art and must be
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coordinated with the network administrator(s).
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<p><dt><code>minpoll <i>minpoll</i></code>
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<dd>This option specifies the minimum polling interval for NTP messages,
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in seconds to the power of two. The allowable range is 4 (16 s to 14
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(16384 s) inclusive. The default is 6 (64 s) for all except reference
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clocks.
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<p><dt><code>maxpoll <i>maxpoll</i></code>
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<dd>This option specifies the maximum polling interval for NTP messages,
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in seconds to the power of two. The allowable range is 4 (16 s to 14
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(16384 s) inclusive. The default is 10 (1024 s) for all except reference
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clocks.
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</dl>
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<p><dt><code>broadcastclient [ <i>address</i></code> ]
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<dd>This command directs the local server to listen for broadcast
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messages at the broadcast address <i>address</i> of the local network.
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The default address is the subnet address with the host field bits set
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to ones. Upon hearing a broadcast message for the first time, the local
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server measures the nominal network delay using a brief client/server
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exchange with the remote server, then enters the broadcastclient mode,
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in which it listens for and synchronizes to succeeding broadcast
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messages. Note that, in order to avoid accidental or malicious
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disruption in this mode, both the local and remote servers should
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operate using authentication and the same trusted key and key
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identifier.
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<p><dt><code>multicastclient [ <i>address</i> ] [ ... ]</code>
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<dd>This command directs the local server to listen for multicast
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messages at the group <i>address</i>(es) of the global network. The
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default address is that assigned by the Numbers Czar to NTP (224.0.1.1).
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This command operates in the same way as the
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<code>broadcastclient</code> command, but uses IP multicasting. Support
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for this command requires a multicast kernel.
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<p><dt><code>driftfile <i>driftfile</i></code>
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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, it
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is read at startup in order to set the initial frequency offset and then
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updated once per hour with the current frequency offset computed by the
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daemon. If the file does not exist or this command is not given, the
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initial frequency offset is assumed zero. In this case, it may take some
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hours for the frequency to stabilize and the residual timing errors to
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subside.
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<p><dd>The <code>ntp.drift</code> file format consists of a single line
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containing a single floating point number, which records the frequency
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offset measured in parts-per-million (PPM). That the file is updated
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once per hour by first writing the current drift value into a temporary
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file and then renaming this file to replace the old version. This
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implies that <code>xntpd</code> must have write permission for the
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directory the drift file is located in, and that file system links,
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symbolic or otherwise, should probably be avoided.
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<p><dt><code>enable auth | bclient | monitor | pll | pps | stats</code>
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<br><code>disable auth | bclient | monitor | pll | pps | stats</code>
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<dd>Provides a way to enable or disable various server options. Flags
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not mentioned are unaffected. Note that all of these flags can be
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controlled remotely using the <a href =
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"xntpdc.html"><code>xntpdc</code></a> utility program.
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<dl>
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<dt><code>auth</code>
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<dd>Enables the server to synchronize with unconfigured peers only if
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the peer has been correctly authenticated using a trusted key and key
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identifier. The default for this flag is enable.
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<p><dt><code>bclient</code>
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<dd>Enables the server to listen for a message from a broadcast or
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multicast server, as in the <code>multicastclient</code> command with
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default address. The default for this flag is disable.
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<p><dt><code>monitor</code>
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<dd>Enables the monitoring facility. See the <code>xntpdc</code> program
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and the <code>monlist</code> command or further information. The default
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for this flag is enable.
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<p><dt><code>pll</code>
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<dd>Enables the server to adjust its local clock by means of NTP. If
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disabled, the local clock free-runs at its intrinsic time and frequency
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offset. This flag is useful in case the local clock is controlled by
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some other device or protocol and NTP is used only to provide
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synchronization to other clients. In this case, the local clock driver
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is used. See the <a href = "refclock.html">Reference Clock Drivers </a>
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page for further information. The default for this flag is enable.
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<p><dt><code>pps</code>
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<dd>Enables the pulse-per-second (PPS) signal when frequency and time is
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disciplined by the precision time kernel modifications. See the <a href
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= "kern.html"> A Kernel Model for Precision Timekeeping </a> page for
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further information. The default for this flag is disable.
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<p><dt><code>stats</code>
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<dd>Enables the statistics facility. See the <a href="monopt.html">
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Monitoring Options </a>
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page for further information. The default for this flag is enable.
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</dl>
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<p><dt><code>tick value</code>
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<dd>If no value for <code>tick</code> can be found from the kernel, use
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this value. This is the "normalized" value; if your system
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keeps <code>tick</code> in nanoseconds you must divide your
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value by 1000. The expected range of the value is between 900
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and 11,000 (don't use the comma in the config file).
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<p><dt><code>tickadj value</code>
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<dd>If no value for <code>tickadj</code> can be found in the
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kernel, use this value. The value must be "normalized"; if
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your system keeps <code>tickadj</code> in nanoseconds you must
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divide your value by 1000. The expected range of the value is
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between 1 and 50.
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</dl>
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<hr><address>David L. Mills (mills@udel.edu)</address></body></html>
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