19c2daa00SOllivier Robert<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 29c2daa00SOllivier Robert<html> 39c2daa00SOllivier Robert<head> 4ea906c41SOllivier Robert<meta http-equiv="content-type" content="text/html;charset=iso-8859-1"> 52b15cb3dSCy Schubert<title>Miscellaneous Commands and Options</title> 69c2daa00SOllivier Robert<link href="scripts/style.css" type="text/css" rel="stylesheet"> 79c2daa00SOllivier Robert</head> 89c2daa00SOllivier Robert<body> 92b15cb3dSCy Schubert<h3>Miscellaneous Commands and Options</h3> 109c2daa00SOllivier Robert<img src="pic/boom3.gif" alt="gif" align="left"><a href="http://www.eecis.udel.edu/~mills/pictures.html">from <i>Pogo</i>, Walt Kelly</a> 119c2daa00SOllivier Robert<p>We have three, now looking for more.</p> 122b15cb3dSCy Schubert<p>Last update: 132d4e511cSCy Schubert <!-- #BeginDate format:En2m -->11-Feb-2020 14:00<!-- #EndDate --> 142b15cb3dSCy Schubert UTC</p> 159c2daa00SOllivier Robert<br clear="left"> 169c2daa00SOllivier Robert<h4>Related Links</h4> 172b15cb3dSCy Schubert<script type="text/javascript" language="javascript" src="scripts/command.txt"></script> 182b15cb3dSCy Schubert<script type="text/javascript" language="javascript" src="scripts/miscopt.txt"></script> 199c2daa00SOllivier Robert<hr> 202b15cb3dSCy Schubert<h4>Commands and Options</h4> 219c2daa00SOllivier Robert<dl> 222b15cb3dSCy Schubert <dt id="broadcastdelay"><tt>broadcastdelay <i>delay</i></tt></dt> 232b15cb3dSCy Schubert <dd>In broadcast and multicast modes, means are required to determine the network delay between the server and client. Ordinarily, this is done automatically by the initial calibration exchanges between the client and server. In some cases, the exchange might not be possible due to network or server access controls. The value of <em><tt>delay</tt></em> is by default zero, in which case the exchange is enabled. If <em><tt>delay</tt></em> is greater than zero, it becomes the roundtrip delay (s), as measured by the Unix <tt>ping</tt> program, and the exchange is disabled. </dd> 242b15cb3dSCy Schubert <dt> </dt> 252b15cb3dSCy Schubert <dt id="driftfile"><tt>driftfile <i>driftfile</i></tt></dt> 262b15cb3dSCy Schubert <dd>This command specifies the complete path and name of the file used to record the frequency of the local clock oscillator. This is the same operation as the <tt>-f</tt> command line option. This command is mutually exclusive with the <tt>freq</tt> option of the <tt>tinker</tt> command.</dd> 272b15cb3dSCy Schubert <dd> If the file exists, it is read at startup in order to set the initial frequency and then updated once per hour or more with the current frequency computed by the daemon. If the file name is specified, but the file itself does not exist, the starts with an initial frequency of zero and creates the file when writing it for the first time. If this command is not given, the daemon will always start with an initial frequency of zero.</dd> 282b15cb3dSCy Schubert <dd>The file format consists of a single line containing a single floating point number, which records the frequency offset measured in parts-per-million (PPM). The file is updated by first writing the current drift value into a temporary file and then renaming this file to replace the old version.</dd> 29276da39aSCy Schubert <dt id="dscp"><tt>dscp <i>dscp</i></tt></dt> 30276da39aSCy Schubert <dd>This command specifies the Differentiated Services Code Point (DSCP) value that is used in sent NTP packets. The default value is 46 for Expedited Forwarding (EF).</dd> 3168ba7e87SXin LI <dt id="enable"><tt>enable [auth | bclient | calibrate | kernel | mode7 | monitor | ntp | stats | unpeer_crypto_early | unpeer_crypto_nak_early | unpeer_digest_early]</tt></dt> 3268ba7e87SXin LI 3368ba7e87SXin LI <dt><tt>disable [auth | bclient | calibrate | kernel | mode7 | monitor | ntp | stats | unpeer_crypto_early | unpeer_crypto_nak_early | unpeer_digest_early]</tt></dt> 342b15cb3dSCy Schubert <dd>Provides a way to enable or disable various system options. Flags not mentioned are unaffected. Note that most of these flags can be modified remotely using <a href="ntpq.html"><tt>ntpq</tt></a> utility program's <tt>:config</tt> and <tt>config-from-file</tt> commands. 359c2daa00SOllivier Robert <dl> 362b15cb3dSCy Schubert <dt><tt>auth</tt></dt> 372b15cb3dSCy Schubert <dd>Enables the server to synchronize with unconfigured peers only if the peer has been correctly authenticated using either public key or private key cryptography. The default for this flag is enable.</dd> 382b15cb3dSCy Schubert <dt><tt>bclient</tt></dt> 392b15cb3dSCy Schubert <dd>Enables the server to listen for a message from a broadcast or multicast server, as in the <tt>multicastclient</tt> command with default address. The default for this flag is disable.</dd> 402b15cb3dSCy Schubert <dt><tt>calibrate</tt></dt> 412b15cb3dSCy Schubert <dd>Enables the calibrate feature for reference clocks. The default for this flag is disable.</dd> 422b15cb3dSCy Schubert <dt><tt>kernel</tt></dt> 432b15cb3dSCy Schubert <dd>Enables the kernel time discipline, if available. The default for this flag is enable if support is available, otherwise disable.</dd> 442b15cb3dSCy Schubert <dt><tt>mode7</tt></dt> 452b15cb3dSCy Schubert <dd>Enables processing of NTP mode 7 implementation-specific requests which are used by the deprecated <tt>ntpdc</tt> program. The default for this flag is disable. This flag is excluded from runtime configuration using <tt>ntpq</tt>. The <tt>ntpq</tt> program provides the same capabilities as <tt>ntpdc</tt> using standard mode 6 requests.</dd> 462b15cb3dSCy Schubert <dt><tt>monitor</tt></dt> 472b15cb3dSCy Schubert <dd>Enables the monitoring facility. See the <a href="ntpq.html"><tt>ntpq</tt> program</a> and the <tt>monstats</tt> and <tt>mrulist</tt> commands, as well as the <a href="accopt.html#discard">Access Control Options</a> for details. 482b15cb3dSCy Schubert The monitoring facility is also enabled by the presence of <a href="accopt.html#limited"><tt>limited</tt></a> in any <tt>restrict</tt> commands. The default for this flag is enable.</dd> 492b15cb3dSCy Schubert <dt><tt>ntp</tt></dt> 502b15cb3dSCy Schubert <dd>Enables time and frequency discipline. In effect, this switch opens and closes the feedback loop, which is useful for testing. The default for this flag is enable.</dd> 512b15cb3dSCy Schubert <dt><tt>stats</tt></dt> 522b15cb3dSCy Schubert <dd>Enables the statistics facility. See the <a href="monopt.html">Monitoring Options</a> page for further information. The default for this flag is enabled. This flag is excluded from runtime configuration using <tt>ntpq</tt>.</dd> 5368ba7e87SXin LI| unpeer_crypto_early | unpeer_crypto_nak_early | unpeer_digest_early 5468ba7e87SXin LI <dt><tt>unpeer_crypto_early</tt></dt> 5568ba7e87SXin LI <dd>Enables the early resetting of an association in case of a crypto failure. This is generally a feature, but it can be used in a DoS attack. If you are seeing these packets being used as a DoS attack against your server, you should disable this flag. The default for this flag is enabled. This flag is excluded from runtime configuration using <tt>ntpq</tt>.</dd> 5668ba7e87SXin LI <dt><tt>unpeer_crypto_nak_early</tt></dt> 5768ba7e87SXin LI <dd>Enables the early resetting of an association in case of a crypto_NAK message. This is generally a feature, but it can be used in a DoS attack. If you are seeing these packets being used as a DoS attack against your server, you should disable this flag. The default for this flag is enabled. This flag is excluded from runtime configuration using <tt>ntpq</tt>.</dd> 5868ba7e87SXin LI <dt><tt>unpeer_digest_early</tt></dt> 5968ba7e87SXin LI <dd>Enables the early resetting of an association in case of an autokey digest failur. This is generally a feature, but it can be used in a DoS attack. If you are seeing these packets being used as a DoS attack against your server, you should disable this flag. The default for this flag is enabled. This flag is excluded from runtime configuration using <tt>ntpq</tt>.</dd> 609c2daa00SOllivier Robert </dl> 612b15cb3dSCy Schubert </dd> 622b15cb3dSCy Schubert <dt id="includefile"><tt>includefile <i>includefile</i></tt></dt> 632b15cb3dSCy Schubert <dd>This command allows additional configuration commands to be included from a separate file. Include files may be nested to a depth of five; upon reaching the end of any include file, command processing resumes in the previous configuration file. This option is useful for sites that run <tt>ntpd</tt> on multiple hosts, with (mostly) common options (e.g., a restriction list).</dd> 642b15cb3dSCy Schubert <dt id="interface"><tt>interface [listen | ignore | drop] [all | ipv4 | ipv6 | wildcard | <i>name</i> | <i>address</i>[/<i>prefixlen</i>]]</tt></dt> 652b15cb3dSCy Schubert <dd>This command controls which network addresses <tt>ntpd</tt> opens, and whether input is dropped without processing. The first parameter determines the action for addresses which match the second parameter. That parameter specifies a class of addresses, or a specific interface name, or an address. In the address case, <tt><i>prefixlen</i></tt> determines how many bits must match for this rule to apply. <tt>ignore</tt> prevents opening matching addresses, <tt>drop</tt> causes <tt>ntpd</tt> to open the address and drop all received packets without examination. Multiple <tt>interface</tt> commands can be used. The last rule which matches a particular address determines the action for it. <tt>interface</tt> commands are disabled if any <a href="ntpd.html#--interface"><tt>-I</tt></a>, <a href="ntpd.html#--interface"><tt>--interface</tt></a>, <a href="ntpd.html#--novirtualips"><tt>-L</tt></a>, or <a href="ntpd.html#--novirtualips"><tt>--novirtualips</tt></a> command-line options are used. If none of those options are used and no <tt>interface</tt> actions are specified in the configuration file, all available network addresses are opened. The <tt>nic</tt> command is an alias for <tt>interface</tt>.</dd> 662d4e511cSCy Schubert <dt id="leapfile"><tt>leapfile <i>leapfile</i> [checkhash|ignorehash]</tt></dt> 672d4e511cSCy Schubert <dd>This command loads the IERS leapseconds file and initializes the leapsecond values for the next leapsecond time, expiration time and TAI offset. The file can be obtained directly from the IERS at <a href="https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list">https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list</a> or <a href="ftp://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list">ftp://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list</a>. 682d4e511cSCy Schubert <tt>ignorehash</tt> instructs <tt>ntpd</tt> to ignore the hash signature on the file, <tt>checkhash</tt> (which is the default when omitted) needs a hash line in the file to be valid. Files without any hash signature are lodaed in both cases.</dd> 692b15cb3dSCy Schubert <dd>The <i>leapfile</i> is scanned when <tt>ntpd</tt> processes the <tt>leapfile</tt> directive or when <tt>ntpd</tt> detects that <i>leapfile</i> has changed. <tt>ntpd</tt> checks once a day to see if the <i>leapfile</i> has changed.</dd> 702b15cb3dSCy Schubert <dd>While not strictly a security function, the Autokey protocol provides means to securely retrieve the current or updated leapsecond values from a server.</dd> 71276da39aSCy Schubert <dt id="leapsmearinterval"><tt>leapsmearinterval <i>seconds</i></tt></dt> 72276da39aSCy Schubert <dd>This EXPERIMENTAL option is only available if <tt>ntpd</tt> was built with the <tt>--enable-leap-smear</tt> option to the <tt>configure</tt> script. It specifies the interval over which a leap second correction will be applied. Recommended values for this option are between 7200 (2 hours) and 86400 (24 hours). <b>DO NOT USE THIS OPTION ON PUBLIC-ACCESS SERVERS!</b> See http://bugs.ntp.org/2855 for more information.</dd> 732b15cb3dSCy Schubert <dt id="logconfig"><tt>logconfig <i>configkeyword</i></tt></dt> 742b15cb3dSCy Schubert <dd>This command controls the amount and type of output written to the system <tt>syslog</tt> facility or the alternate <tt>logfile</tt> log file. All <i><tt>configkeyword</tt></i> keywords can be prefixed with <tt>=</tt>, <tt>+</tt> and <tt>-</tt>, where <tt>=</tt> sets the <tt>syslogmask</tt>, <tt>+</tt> adds and <tt>-</tt> removes messages. <tt>syslog messages</tt> can be controlled in four classes (<tt>clock</tt>, <tt>peer</tt>, <tt>sys</tt> and <tt>sync</tt>). Within these classes four types of messages can be controlled: informational messages (<tt>info</tt>), event messages (<tt>events</tt>), statistics messages (<tt>statistics</tt>) and status messages (<tt>status</tt>).</dd> 752b15cb3dSCy Schubert <dd>Configuration keywords are formed by concatenating the message class with the event class. The <tt>all</tt> prefix can be used instead of a message class. A message class may also be followed by the <tt>all</tt> keyword to enable/disable all messages of the respective message class. By default, <tt>logconfig</tt> output is set to <tt>allsync</tt>.</dd> 762b15cb3dSCy Schubert <dd>Thus, a minimal log configuration could look like this:</dd> 772b15cb3dSCy Schubert <dd><tt>logconfig=syncstatus +sysevents</tt></dd> 782b15cb3dSCy Schubert <dd>This would just list the synchronizations state of <tt>ntpd</tt> and the major system events. For a simple reference server, the following minimum message configuration could be useful:</dd> 792b15cb3dSCy Schubert <dd><tt>logconfig=syncall +clockall</tt></dd> 802b15cb3dSCy Schubert <dd>This configuration will list all clock information and synchronization information. All other events and messages about peers, system events and so on is suppressed.</dd> 812b15cb3dSCy Schubert <dt id="logfile"><tt>logfile <i>logfile</i></tt></dt> 822b15cb3dSCy Schubert <dd>This command specifies the location of an alternate log file to be used instead of the default system <tt>syslog</tt> facility. This is the same operation as the <tt>-l </tt>command line option.</dd> 832b15cb3dSCy Schubert <dt id="mru"><tt>mru [maxdepth <i>count</i> | maxmem <i>kilobytes</i> | mindepth <i>count</i> | maxage <i>seconds</i> | initalloc <i>count</i> | initmem <i>kilobytes</i> | incalloc <i>count</i> | incmem <i>kilobytes</i>]</tt></dt> 842b15cb3dSCy Schubert <dd>Controls size limits of the monitoring facility Most Recently Used <a href="ntpq.html#mrulist">(MRU) list</a> of client addresses, which is also used by the <a href="accopt.html#discard">rate control facility</a>. 85ea906c41SOllivier Robert <dl> 862b15cb3dSCy Schubert <dt><tt>maxdepth <i>count</i><br> 872b15cb3dSCy Schubert maxmem <i>kilobytes</i></tt></dt> 882b15cb3dSCy Schubert <dd>Equivalent upper limits on the size of the MRU list, in terms of entries or kilobytes. The actual limit will be up to <tt>incalloc</tt> entries or <tt>incmem</tt> kilobytes larger. As with all 892b15cb3dSCy Schubert of the <tt>mru</tt> options offered in units of entries or kilobytes, if both <tt>maxdepth</tt> and <tt>maxmem</tt> are used, the last one used controls. The default is 1024 kilobytes.</dd> 902b15cb3dSCy Schubert <dt><tt>mindepth <i>count</i></tt></dt> 912b15cb3dSCy Schubert <dd>Lower limit on the MRU list size. When the MRU list has fewer than <tt>mindepth</tt> entries, existing entries are never removed to make room for newer ones, regardless of their age. 922b15cb3dSCy Schubert The default is 600 entries.</dd> 932b15cb3dSCy Schubert <dt><tt>maxage <i>seconds</i></tt></dt> 942b15cb3dSCy Schubert <dd>Once the MRU list has <tt>mindepth</tt> entries and an additional client address is to be added to the list, if the oldest entry was updated more than <tt>maxage</tt> seconds ago, that entry 952b15cb3dSCy Schubert is removed and its storage reused. If the oldest entry was updated more recently, the MRU list 962b15cb3dSCy Schubert is grown, subject to <tt>maxdepth</tt>/<tt>maxmem</tt>. The default is 64 seconds.</dd> 972b15cb3dSCy Schubert <dt><tt>initalloc <i>count</i><br> 982b15cb3dSCy Schubert initmem <i>kilobytes</i></tt></dt> 992b15cb3dSCy Schubert <dd>Initial memory allocation at the time the monitoring facility is first enabled, in terms of entries or kilobytes. The default is 4 kilobytes.</dd> 1002b15cb3dSCy Schubert <dt><tt>incalloc <i>count</i><br> 1012b15cb3dSCy Schubert incmem <i>kilobytes</i></tt></dt> 1022b15cb3dSCy Schubert <dd>Size of additional memory allocations when growing the MRU list, in entries or kilobytes. The default is 4 kilobytes.</dd> 1032b15cb3dSCy Schubert </dl> 1042b15cb3dSCy Schubert </dd> 1052b15cb3dSCy Schubert <dt id="nonvolatile"><tt>nonvolatile <i>threshold</i></tt></dt> 106a25439b6SCy Schubert <dd>Specify the <i><tt>threshold</tt></i> in seconds to write the frequency file, with default of 1e-7 (0.1 PPM). The frequency file is inspected each hour. If the difference between the current frequency and the last value written exceeds the threshold, the file is written and the <tt><em>threshold</em></tt> becomes the new threshold value. If the threshold is not exceeded, it is reduced by half. This is intended to reduce the frequency of unnecessary file writes for embedded systems with nonvolatile memory.</dd> 1072b15cb3dSCy Schubert <dt id="phone"><tt>phone <i>dial</i> ...</tt></dt> 10809100258SXin LI <dd>This command is used in conjunction with the ACTS modem driver (type 18) or the JJY driver (type 40 mode 100 - 180). 10909100258SXin LI For the ACTS modem driver (type 18), the arguments consist of a maximum of 10 telephone numbers used to dial USNO, NIST or European time services. 11009100258SXin LI For the JJY driver (type 40 mode 100 - 180), the argument is one telephone number used to dial the telephone JJY service. 11109100258SXin LI The Hayes command ATDT is normally prepended to the number, which can contain other modem control codes as well.</dd> 1122d4e511cSCy Schubert <dt id="pollskewlist" 113*a466cc55SCy Schubert ><tt>pollskewlist</tt> <tt>[</tt><i>poll</i> <i>early late</i><tt>]</tt> <tt>...</tt> <tt>[default </tt><i>early late</i><tt>]</tt></dt> 1142d4e511cSCy Schubert<dd>Enable skewing of our poll requests to our servers. 1152d4e511cSCy Schubert<i>poll</i> 1162d4e511cSCy Schubertis a number between 3 and 17 inclusive, identifying a specific poll interval. 1172d4e511cSCy SchubertA poll interval is 2^n seconds in duration, 1182d4e511cSCy Schubertso a poll value of 3 corresponds to 8 seconds 1192d4e511cSCy Schubertand 1202d4e511cSCy Schuberta poll interval of 17 corresponds to 1212d4e511cSCy Schubert131,072 seconds, or about a day and a half. 1222d4e511cSCy SchubertThe next two numbers must be between 0 and one-half of the poll interval, 1232d4e511cSCy Schubertinclusive. 124*a466cc55SCy Schubert<i>early</i> specifies how early the poll may start, while 125*a466cc55SCy Schubert<i>late</i> specifies how late the poll may be delayed. 1262d4e511cSCy SchubertWith no arguments, internally specified default values are chosen.</dd> 1272b15cb3dSCy Schubert <dt id="reset"><tt>reset [allpeers] [auth] [ctl] [io] [mem] [sys] [timer]</tt></dt> 1282b15cb3dSCy Schubert <dd>Reset one or more groups of counters maintained by ntpd and exposed by <tt>ntpq</tt> and <tt>ntpdc</tt>.</dd> 129276da39aSCy Schubert <dt id="rlimit"><tt>rlimit [memlock <i>Nmegabytes</i> | stacksize <i>N4kPages</i> | filenum <i>Nfiledescriptors</i>]</tt></dt> 130276da39aSCy Schubert <dd>This command alters certain process storage allocation limits, and is only available on some operating systems. Options are as follows:</dd> 131276da39aSCy Schubert <dd> 132276da39aSCy Schubert <dl> 133276da39aSCy Schubert <dt><tt>memlock <i>Nmegabytes</i></tt></dt> 1349034852cSGleb Smirnoff <dd>Specify the number of megabytes of memory that should be allocated and locked. Probably only available under Linux, this option may be useful when dropping root (the <tt>-i</tt> option). The default is 32 megabytes on non-Linux machines, and -1 under Linux. -1 means "do not lock the process into memory". 0 means "lock whatever memory the process wants into memory".</dd> 135276da39aSCy Schubert <dt><tt>stacksize <i>N4kPages</i></tt></dt> 136276da39aSCy Schubert <dd>Specifies the maximum size of the process stack on systems with the <tt>mlockall()</tt> function. Defaults to 50 4k pages (200 4k pages in OpenBSD).</dd> 137276da39aSCy Schubert <dt><tt>filenum <i>Nfiledescriptors</i></tt></dt> 138276da39aSCy Schubert <dd>Specifies the maximum number of file descriptors ntp may have open at the same time. Defaults to system default.</dd> 139276da39aSCy Schubert </dl> 140276da39aSCy Schubert </dd> 1412b15cb3dSCy Schubert <dt id="saveconfigdir"><tt>saveconfigdir <i>directory_path</i></tt></dt> 1422b15cb3dSCy Schubert <dd>Specify the directory in which to write configuration snapshots requested with <tt>ntpq</tt>'s <a href="ntpq.html#saveconfig">saveconfig</a> command. If <tt>saveconfigdir</tt> does not appear in the configuration file, saveconfig requests are rejected by ntpd.</dd> 1432b15cb3dSCy Schubert <dt id="setvar"><tt>setvar <i>variable</i> [default]</tt></dt> 1442b15cb3dSCy Schubert <dd>This command adds an additional system variable. These variables can be used to distribute additional information such as the access policy. If the variable of the form <tt><i>name</i> = <i>value</i></tt> is followed by the <tt>default</tt> keyword, the variable will be listed as part of the default system variables (<tt>ntpq rv</tt> command). These additional variables serve informational purposes only. They are not related to the protocol other that they can be listed. The known protocol variables will always override any variables defined via the <tt>setvar</tt> mechanism. There are three special variables that contain the names of all variable of the same group. The <tt>sys_var_list</tt> holds the names of all system variables. The <tt>peer_var_list</tt> holds the names of all peer variables and the <tt>clock_var_list</tt> holds the names of the reference clock variables.</dd> 1452b15cb3dSCy Schubert <dt id="tinker"><tt>tinker [allan <i>allan</i> | dispersion <i>dispersion</i> | freq <i>freq</i> | huffpuff <i>huffpuff</i> | panic <i>panic</i> | step <i>step</i> | stepout <i>stepout</i>]</tt></dt> 1462b15cb3dSCy Schubert <dd>This command alters certain system variables used by the clock discipline algorithm. The default values of these variables have been carefully optimized for a wide range of network speeds and reliability expectations. Very rarely is it necessary to change the default values; but, some folks can't resist twisting the knobs. Options are as follows:</dd> 147ea906c41SOllivier Robert <dd> 1482b15cb3dSCy Schubert <dl> 1492b15cb3dSCy Schubert <dt><tt>allan <i>allan</i></tt></dt> 150e27abb66SXin LI <dd>Specifies the Allan intercept, which is a parameter of the PLL/FLL clock discipline algorithm, in log2 seconds with default 11 (2048 s).</dd> 1512b15cb3dSCy Schubert <dt><tt>dispersion <i>dispersion</i></tt></dt> 1522b15cb3dSCy Schubert <dd>Specifies the dispersion increase rate in parts-per-million (PPM) with default 15 PPM.</dd> 1532b15cb3dSCy Schubert <dt><tt>freq <i>freq</i></tt></dt> 1542b15cb3dSCy Schubert <dd>Specifies the frequency offset in parts-per-million (PPM). This option is mutually exclusive with the driftfile command.</dd> 1552b15cb3dSCy Schubert <dt><tt>huffpuff <i>huffpuff</i></tt></dt> 1562b15cb3dSCy Schubert <dd>Specifies the huff-n'-puff filter span, which determines the most recent interval the algorithm will search for a minimum delay. The lower limit is 900 s (15 min), but a more reasonable value is 7200 (2 hours).See the <a href="huffpuff.html">Huff-n'-Puff Filter</a> page for further information.</dd> 1572b15cb3dSCy Schubert <dt><tt>panic <i>panic</i></tt></dt> 1582b15cb3dSCy Schubert <dd>Specifies the panic threshold in seconds with default 1000 s. If set to zero, the panic sanity check is disabled and a clock offset of any value will be accepted.</dd> 1592b15cb3dSCy Schubert <dt><tt>step <i>step</i></tt></dt> 1602b15cb3dSCy Schubert <dd>Specifies the step threshold in seconds. The default without this command is 0.128 s. If set to zero, step adjustments will never occur. Note: The kernel time discipline is disabled if the step threshold is set to zero or greater than 0.5 1612b15cb3dSCy Schubert s. Further details are on the <a href="clock.html">Clock State Machine</a> page.</dd> 1622b15cb3dSCy Schubert <dt><tt>stepout <i>stepout</i></tt></dt> 1632b15cb3dSCy Schubert <dd>Specifies the stepout threshold in seconds. The default without this command is 300 s. Since this option also affects the training and startup intervals, it should not be set less than the default. Further details are on the <a href="clock.html">Clock State Machine</a> page.</dd> 164ea906c41SOllivier Robert </dl> 1652b15cb3dSCy Schubert </dd> 1662d4e511cSCy Schubert <dt id="tos"><tt>tos [basedate <i>date</i> | bcpollbstep <i>poll-gate</i> | beacon <i>beacon</i> | ceiling <i>ceiling</i> | cohort {0 | 1} | floor <i>floor</i> | maxclock <i>maxclock </i>| maxdist <i>maxdist</i> | minclock <i>minclock</i> | mindist <i>mindist </i>| minsane <i>minsane</i> | orphan <i>stratum</i> | orphanwait <em>delay</em>]</tt></dt> 1672b15cb3dSCy Schubert <dd>This command alters certain system variables used by the the clock selection and clustering algorithms. The default values of these variables have been carefully optimized for a wide range of network speeds and reliability expectations. Very rarely is it necessary to change the default values; but, some folks can't resist twisting the knobs. It can be used to select the quality and quantity of peers used to synchronize the system clock and is most useful in dynamic server discovery schemes. The options are as follows:</dd> 168ea906c41SOllivier Robert <dd> 169ea906c41SOllivier Robert <dl> 17009100258SXin LI <dt><tt>basedate <i>date</i></tt></dt> 1712d4e511cSCy Schubert <dd>Set NTP and GPS era anchor. <tt><i>date</i></tt> is either a date in ISO8601 format (<i>YYYY-MM-DD</i>) or an integer giving the days since 1900-01-01, the start of the NTP epoch. <tt>ntpd</tt> will clamp the system time to an era starting with the begin of this this day (00:00:00Z), covering a range of 2<sup>32</sup> seconds or roughly 136 years. The lowest accepted value is effectively 1970-01-02.<br> 1722d4e511cSCy Schubert The GPS era base is the next Sunday on or following the base date, but obviously not before 1980-01-06. GPS time stamps are mapped into the 1024 weeks following the GPS base.<br> 1732d4e511cSCy Schubert The default value is derived from the repository or build time stamp, minus 11 days. 1970-01-02 was chosen as lower bound so the <em>local</em> time is always after 1970-01-01,00:00. Some systems get into trouble if this is not the case.<p> 1742d4e511cSCy Schubert <b><u>ATTENTION:</u></b> If the system clock is before the effective (implied or specific) basedate, the system clock will be set to the base date once and immediately when <tt>ntpd</tt> starts. This helps systems that have lost time completely to recover. Though not noticeable under normal conditions, it <em>can</em> happen. Check the logs if starting <tt>ntpd</tt> causes sudden clock moves. 1752d4e511cSCy Schubert </dd> 176f391d6bcSXin LI <dt><tt>bcpollbstep <i>poll-gate</i></tt></dt> 177f391d6bcSXin LI <dd>This option will cause the client to delay believing backward time steps from a broadcast server for <tt>bcpollbstep</tt> poll intervals. NTP Broadcast networks are expected to be trusted, and if the server's time gets stepped backwards then it's desireable that the clients follow this change as soon as possible. However, in spite of various protections built-in to the broadcast protocol, it is possible that an attacker could perform a carefully-constructed replay attack and cause clients to erroneously step their clocks backward. If the risk of a successful broadcast replay attack is greater than the risk of the clients being out of sync in the event that there is a backward step on the broadcast time servers, this option may be used to cause the clients to delay beliveving backward time steps until <i>poll-gate</i> consecutive polls have been received. The default is 0, which means the client will accept these steps upon receipt. Any value from 0 to 4 can be specified.</dd> 1782b15cb3dSCy Schubert <dt><tt>beacon <i>beacon</i></tt></dt> 1792b15cb3dSCy Schubert <dd>The manycast server sends packets at intervals of 64 s if less than <tt>maxclock</tt> servers are available. Otherwise, it sends packets at the <i><tt>beacon</tt></i> interval in seconds. The default is 3600 s. See the <a href="discover.html">Automatic Server Discovery</a> page for further details.</dd> 1802b15cb3dSCy Schubert <dt><tt>ceiling <i>ceiling</i></tt></dt> 1812b15cb3dSCy Schubert <dd>Specify the maximum stratum (exclusive) for acceptable server packets. The default is 16. See the <a href="discover.html">Automatic Server Discovery</a> page for further details.</dd> 1822b15cb3dSCy Schubert <dt><tt>cohort { 0 | 1 }</tt></dt> 1832b15cb3dSCy Schubert <dd>Specify whether (1) or whether not (0) a server packet will be accepted for the same stratum as the client. The default is 0. See the <a href="discover.html">Automatic Server Discovery</a> page for further details.</dd> 1842b15cb3dSCy Schubert <dt><tt>floor <i>floor</i></tt></dt> 1852b15cb3dSCy Schubert <dd>Specify the minimum stratum (inclusive) for acceptable server packets. The default is 1. See the <a href="discover.html">Automatic Server Discovery</a> page for further details.</dd> 1862b15cb3dSCy Schubert <dt><tt>maxclock <i>maxclock</i></tt></dt> 1872b15cb3dSCy Schubert <dd>Specify the maximum number of servers retained by the server discovery schemes. The default is 10. See the <a href="discover.html">Automatic Server Discovery</a> page for further details.</dd> 1882b15cb3dSCy Schubert <dt><tt>maxdist <i>maxdistance</i></tt></dt> 1892b15cb3dSCy Schubert <dd>Specify the synchronization distance threshold used by the clock selection algorithm. The default is 1.5 s. This determines both the minimum number of packets to set the system clock and the maximum roundtrip delay. It can be decreased to improve reliability or increased to synchronize clocks on the Moon or planets.</dd> 1902b15cb3dSCy Schubert <dt><tt>minclock <i>minclock</i></tt></dt> 1912b15cb3dSCy Schubert <dd>Specify the number of servers used by the clustering algorithm as the minimum to include on the candidate list. The default is 3. This is also the number of servers to be averaged by the combining algorithm.</dd> 1922b15cb3dSCy Schubert <dt><tt>mindist <i>mindistance</i></tt></dt> 1932b15cb3dSCy Schubert <dd>Specify the minimum distance used by the selection and anticlockhop 1942b15cb3dSCy Schubert algorithm. Larger values increase the tolerance for outliers; 1952b15cb3dSCy Schubert smaller values increase the selectivity. The default is .001 s. In some 1962b15cb3dSCy Schubert cases, such as reference clocks with high jitter and a PPS signal, it is 1972b15cb3dSCy Schubert useful to increase the value to insure the intersection interval is 1982b15cb3dSCy Schubert always nonempty.</dd> 1992b15cb3dSCy Schubert <dt><tt>minsane <i>minsane</i></tt></dt> 2002b15cb3dSCy Schubert <dd>Specify the number of servers used by the selection algorithm as the minimum to set the system clock. The default is 1 for legacy purposes; however, for critical applications the value should be somewhat higher but less than <tt>minclock</tt>.</dd> 2012b15cb3dSCy Schubert <dt><tt>orphan <i>stratum</i></tt></dt> 2022b15cb3dSCy Schubert <dd>Specify the orphan stratum with default 16. If less than 16 this is the stratum assumed by the root servers. See the <a href="orphan.html">Orphan Mode</a> page for further details.</dd> 2032b15cb3dSCy Schubert <dt><tt>orphanwait <em>delay</em></tt></dt> 2042b15cb3dSCy Schubert <dd>Specify the delay in seconds from the time all sources are lost until orphan parent mode is enabled with default 300 s (five minutes). During this period, the local clock driver and the modem driver are not selectable, unless marked with the <tt>prefer</tt> keyword. This allows time for one or more primary sources to become reachable and selectable before using backup sources, and avoids transient use of the backup sources at startup.</dd> 205ea906c41SOllivier Robert </dl> 2062b15cb3dSCy Schubert </dd> 2072b15cb3dSCy Schubert <dt id="trap"><tt>trap <i>host_address</i> [port <i>port_number</i>] [interface <i>interfSace_address</i>]</tt></dt> 2082b15cb3dSCy Schubert <dd>This command configures a trap receiver at the given host address and port number for sending messages with the specified local interface address. If the port number is unspecified, a value of 18447 is used. If the interface address is not specified, the message is sent with a source address of the local interface the message is sent through. Note that on a multihomed host the interface used may vary from time to time with routing changes.</dd> 2092b15cb3dSCy Schubert <dd>The trap receiver will generally log event messages and other information from the server in a log file. While such monitor programs may also request their own trap dynamically, configuring a trap receiver will ensure that no messages are lost when the server is started.</dd> 2102b15cb3dSCy Schubert <dt id="ttl"><tt>ttl <i>hop</i> ...</tt></dt> 2112b15cb3dSCy Schubert <dd>This command specifies a list of TTL values in increasing order. up to 8 values can be specified. In manycast mode these values are used in turn in an expanding-ring search. The default is eight multiples of 32 starting at 31.</dd> 212ea906c41SOllivier Robert</dl> 2139c2daa00SOllivier Robert<hr> 2149c2daa00SOllivier Robert<script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 2159c2daa00SOllivier Robert</body> 2169c2daa00SOllivier Robert</html> 217
