1<html lang="en"> 2<head> 3<title>ntpd: Network Time Protocol (NTP) Daemon User's Manual</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="ntpd: Network Time Protocol (NTP) Daemon User's Manual"> 6<meta name="generator" content="makeinfo 4.7"> 7<link title="Top" rel="top" href="#Top"> 8<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 9<meta http-equiv="Content-Style-Type" content="text/css"> 10<style type="text/css"><!-- 11 pre.display { font-family:inherit } 12 pre.format { font-family:inherit } 13 pre.smalldisplay { font-family:inherit; font-size:smaller } 14 pre.smallformat { font-family:inherit; font-size:smaller } 15 pre.smallexample { font-size:smaller } 16 pre.smalllisp { font-size:smaller } 17 span.sc { font-variant:small-caps } 18 span.roman { font-family: serif; font-weight: normal; } 19--></style> 20</head> 21<body> 22<h1 class="settitle">ntpd: Network Time Protocol (NTP) Daemon User's Manual</h1> 23<div class="node"> 24<p><hr> 25<a name="Top"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Description">ntpd Description</a>, 26Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>, 27Up: <a rel="up" accesskey="u" href="#dir">(dir)</a> 28<br> 29</div> 30 31<h2 class="unnumbered">ntpd: Network Time Protocol (NTP) Daemon User Manual</h2> 32 33<p>The <code>ntpd</code> program is an operating system daemon that synchronizes the 34system clock to remote NTP time servers or local reference clocks. 35It is a complete implementation of NTP version 4 defined by RFC-5905, but 36also retains compatible with version 3 defined by RFC-1305 and versions 371 and 2, defined by RFC-1059 and RFC-1119, respectively. 38The program can operate in any of several modes, including client/server, 39symmetric and broadcast modes, and with both symmetric-key and public-key 40cryptography. 41 42 <p>This document applies to version 4.2.8p9 of <code>ntpd</code>. 43 44<ul class="menu"> 45<li><a accesskey="1" href="#ntpd-Description">ntpd Description</a>: Description 46<li><a accesskey="2" href="#ntpd-Invocation">ntpd Invocation</a>: Invoking ntpd 47<li><a accesskey="3" href="#Usage">Usage</a>: Usage 48</ul> 49 50<div class="node"> 51<p><hr> 52<a name="ntpd-Description"></a> 53<br> 54</div> 55 56<!-- node-name, next, previous, up --> 57<h3 class="section">Description</h3> 58 59<p>The <code>ntpd</code> program ordinarily requires 60a configuration file described at <a href="#ntp_002econf">ntp.conf</a>. 61This configuration file contains configuration commands described on 62the pages listed above. 63However a client can discover remote servers and configure them 64automatically. 65This makes it possible to deploy a fleet of workstations without 66specifying configuration details specific to the local environment. 67 68 <p>The <code>ntpd</code> program normally operates continuously while adjusting the 69system time and frequency, but in some cases this might not be 70practical. 71With the <code>-q</code> option <code>ntpd</code> operates as in continuous mode, but 72exits just after setting the clock for the first time. 73Most applications will probably want to specify the <code>iburst</code> 74option with the <code>server</code> command. 75With this option an initial volley of messages is exchanged to 76groom the data and set the clock in about ten seconds' time. 77If nothing is heard after a few minutes' time, 78the daemon times out and exits without setting the clock. 79 80<div class="node"> 81<p><hr> 82<a name="ntpd-Invocation"></a> 83<br> 84</div> 85 86<h3 class="section">Invoking ntpd</h3> 87 88<p><a name="index-ntpd-1"></a><a name="index-NTP-daemon-program-2"></a> 89 90 <p>The 91<code>ntpd</code> 92utility is an operating system daemon which sets 93and maintains the system time of day in synchronism with Internet 94standard time servers. 95It is a complete implementation of the 96Network Time Protocol (NTP) version 4, as defined by RFC-5905, 97but also retains compatibility with 98version 3, as defined by RFC-1305, and versions 1 99and 2, as defined by RFC-1059 and RFC-1119, respectively. 100 101 <p>The 102<code>ntpd</code> 103utility does most computations in 64-bit floating point 104arithmetic and does relatively clumsy 64-bit fixed point operations 105only when necessary to preserve the ultimate precision, about 232 106picoseconds. 107While the ultimate precision is not achievable with 108ordinary workstations and networks of today, it may be required 109with future gigahertz CPU clocks and gigabit LANs. 110 111 <p>Ordinarily, 112<code>ntpd</code> 113reads the 114<code>ntp.conf(5)</code> 115configuration file at startup time in order to determine the 116synchronization sources and operating modes. 117It is also possible to 118specify a working, although limited, configuration entirely on the 119command line, obviating the need for a configuration file. 120This may 121be particularly useful when the local host is to be configured as a 122broadcast/multicast client, with all peers being determined by 123listening to broadcasts at run time. 124 125 <p>If NetInfo support is built into 126<code>ntpd</code> 127then 128<code>ntpd</code> 129will attempt to read its configuration from the 130NetInfo if the default 131<code>ntp.conf(5)</code> 132file cannot be read and no file is 133specified by the 134<code>-c</code> 135option. 136 137 <p>Various internal 138<code>ntpd</code> 139variables can be displayed and 140configuration options altered while the 141<code>ntpd</code> 142is running 143using the 144<code>ntpq(1ntpqmdoc)</code> 145and 146<code>ntpdc(1ntpdcmdoc)</code> 147utility programs. 148 149 <p>When 150<code>ntpd</code> 151starts it looks at the value of 152<code>umask(2)</code>, 153and if zero 154<code>ntpd</code> 155will set the 156<code>umask(2)</code> 157to 022. 158 159 <p>This section was generated by <strong>AutoGen</strong>, 160using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntpd</code> program. 161This software is released under the NTP license, <http://ntp.org/license>. 162 163<ul class="menu"> 164<li><a accesskey="1" href="#ntpd-usage">ntpd usage</a>: ntpd help/usage (<span class="option">--help</span>) 165<li><a accesskey="2" href="#ntpd-ipv4">ntpd ipv4</a>: ipv4 option (-4) 166<li><a accesskey="3" href="#ntpd-ipv6">ntpd ipv6</a>: ipv6 option (-6) 167<li><a accesskey="4" href="#ntpd-authreq">ntpd authreq</a>: authreq option (-a) 168<li><a accesskey="5" href="#ntpd-authnoreq">ntpd authnoreq</a>: authnoreq option (-A) 169<li><a accesskey="6" href="#ntpd-configfile">ntpd configfile</a>: configfile option (-c) 170<li><a accesskey="7" href="#ntpd-driftfile">ntpd driftfile</a>: driftfile option (-f) 171<li><a accesskey="8" href="#ntpd-panicgate">ntpd panicgate</a>: panicgate option (-g) 172<li><a accesskey="9" href="#ntpd-force_002dstep_002donce">ntpd force-step-once</a>: force-step-once option (-G) 173<li><a href="#ntpd-jaildir">ntpd jaildir</a>: jaildir option (-i) 174<li><a href="#ntpd-interface">ntpd interface</a>: interface option (-I) 175<li><a href="#ntpd-keyfile">ntpd keyfile</a>: keyfile option (-k) 176<li><a href="#ntpd-logfile">ntpd logfile</a>: logfile option (-l) 177<li><a href="#ntpd-novirtualips">ntpd novirtualips</a>: novirtualips option (-L) 178<li><a href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>: modifymmtimer option (-M) 179<li><a href="#ntpd-nice">ntpd nice</a>: nice option (-N) 180<li><a href="#ntpd-pidfile">ntpd pidfile</a>: pidfile option (-p) 181<li><a href="#ntpd-priority">ntpd priority</a>: priority option (-P) 182<li><a href="#ntpd-quit">ntpd quit</a>: quit option (-q) 183<li><a href="#ntpd-propagationdelay">ntpd propagationdelay</a>: propagationdelay option (-r) 184<li><a href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>: saveconfigquit option 185<li><a href="#ntpd-statsdir">ntpd statsdir</a>: statsdir option (-s) 186<li><a href="#ntpd-trustedkey">ntpd trustedkey</a>: trustedkey option (-t) 187<li><a href="#ntpd-user">ntpd user</a>: user option (-u) 188<li><a href="#ntpd-updateinterval">ntpd updateinterval</a>: updateinterval option (-U) 189<li><a href="#ntpd-wait_002dsync">ntpd wait-sync</a>: wait-sync option (-w) 190<li><a href="#ntpd-slew">ntpd slew</a>: slew option (-x) 191<li><a href="#ntpd-usepcc">ntpd usepcc</a>: usepcc option 192<li><a href="#ntpd-pccfreq">ntpd pccfreq</a>: pccfreq option 193<li><a href="#ntpd-mdns">ntpd mdns</a>: mdns option (-m) 194<li><a href="#ntpd-config">ntpd config</a>: presetting/configuring ntpd 195<li><a href="#ntpd-exit-status">ntpd exit status</a>: exit status 196<li><a href="#ntpd-Usage">ntpd Usage</a>: Usage 197<li><a href="#ntpd-Files">ntpd Files</a>: Files 198<li><a href="#ntpd-See-Also">ntpd See Also</a>: See Also 199<li><a href="#ntpd-Bugs">ntpd Bugs</a>: Bugs 200<li><a href="#ntpd-Notes">ntpd Notes</a>: Notes 201</ul> 202 203<div class="node"> 204<p><hr> 205<a name="ntpd-usage"></a>Next: <a rel="next" accesskey="n" href="#ntpd-ipv4">ntpd ipv4</a>, 206Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 207<br> 208</div> 209 210<h4 class="subsection">ntpd help/usage (<span class="option">--help</span>)</h4> 211 212<p><a name="index-ntpd-help-3"></a> 213This is the automatically generated usage text for ntpd. 214 215 <p>The text printed is the same whether selected with the <code>help</code> option 216(<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print 217the usage text by passing it through a pager program. 218<code>more-help</code> is disabled on platforms without a working 219<code>fork(2)</code> function. The <code>PAGER</code> environment variable is 220used to select the program, defaulting to <span class="file">more</span>. Both will exit 221with a status code of 0. 222 223<pre class="example">ntpd - NTP daemon program - Ver. 4.2.8p9-RC 224Usage: ntpd [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \ 225 [ <server1> ... <serverN> ] 226 Flg Arg Option-Name Description 227 -4 no ipv4 Force IPv4 DNS name resolution 228 - prohibits the option 'ipv6' 229 -6 no ipv6 Force IPv6 DNS name resolution 230 - prohibits the option 'ipv4' 231 -a no authreq Require crypto authentication 232 - prohibits the option 'authnoreq' 233 -A no authnoreq Do not require crypto authentication 234 - prohibits the option 'authreq' 235 -b no bcastsync Allow us to sync to broadcast servers 236 -c Str configfile configuration file name 237 -d no debug-level Increase debug verbosity level 238 - may appear multiple times 239 -D Num set-debug-level Set the debug verbosity level 240 - may appear multiple times 241 -f Str driftfile frequency drift file name 242 -g no panicgate Allow the first adjustment to be Big 243 - may appear multiple times 244 -G no force-step-once Step any initial offset correction. 245 -i Str jaildir Jail directory 246 -I Str interface Listen on an interface name or address 247 - may appear multiple times 248 -k Str keyfile path to symmetric keys 249 -l Str logfile path to the log file 250 -L no novirtualips Do not listen to virtual interfaces 251 -n no nofork Do not fork 252 - prohibits the option 'wait-sync' 253 -N no nice Run at high priority 254 -p Str pidfile path to the PID file 255 -P Num priority Process priority 256 -q no quit Set the time and quit 257 - prohibits these options: 258 saveconfigquit 259 wait-sync 260 -r Str propagationdelay Broadcast/propagation delay 261 Str saveconfigquit Save parsed configuration and quit 262 - prohibits these options: 263 quit 264 wait-sync 265 -s Str statsdir Statistics file location 266 -t Str trustedkey Trusted key number 267 - may appear multiple times 268 -u Str user Run as userid (or userid:groupid) 269 -U Num updateinterval interval in seconds between scans for new or dropped interfaces 270 Str var make ARG an ntp variable (RW) 271 - may appear multiple times 272 Str dvar make ARG an ntp variable (RW|DEF) 273 - may appear multiple times 274 -w Num wait-sync Seconds to wait for first clock sync 275 - prohibits these options: 276 nofork 277 quit 278 saveconfigquit 279 -x no slew Slew up to 600 seconds 280 opt version output version information and exit 281 -? no help display extended usage information and exit 282 -! no more-help extended usage information passed thru pager 283 284Options are specified by doubled hyphens and their name or by a single 285hyphen and the flag character. 286 287 288The following option preset mechanisms are supported: 289 - examining environment variables named NTPD_* 290 291Please send bug reports to: <http://bugs.ntp.org, bugs@ntp.org> 292</pre> 293 <div class="node"> 294<p><hr> 295<a name="ntpd-ipv4"></a>Next: <a rel="next" accesskey="n" href="#ntpd-ipv6">ntpd ipv6</a>, 296Previous: <a rel="previous" accesskey="p" href="#ntpd-usage">ntpd usage</a>, 297Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 298<br> 299</div> 300 301<h4 class="subsection">ipv4 option (-4)</h4> 302 303<p><a name="index-ntpd_002dipv4-4"></a> 304This is the “force ipv4 dns name resolution” option. 305 306<p class="noindent">This option has some usage constraints. It: 307 <ul> 308<li>must not appear in combination with any of the following options: 309ipv6. 310</ul> 311 312 <p>Force DNS resolution of following host names on the command line 313to the IPv4 namespace. 314<div class="node"> 315<p><hr> 316<a name="ntpd-ipv6"></a>Next: <a rel="next" accesskey="n" href="#ntpd-authreq">ntpd authreq</a>, 317Previous: <a rel="previous" accesskey="p" href="#ntpd-ipv4">ntpd ipv4</a>, 318Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 319<br> 320</div> 321 322<h4 class="subsection">ipv6 option (-6)</h4> 323 324<p><a name="index-ntpd_002dipv6-5"></a> 325This is the “force ipv6 dns name resolution” option. 326 327<p class="noindent">This option has some usage constraints. It: 328 <ul> 329<li>must not appear in combination with any of the following options: 330ipv4. 331</ul> 332 333 <p>Force DNS resolution of following host names on the command line 334to the IPv6 namespace. 335<div class="node"> 336<p><hr> 337<a name="ntpd-authreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-authnoreq">ntpd authnoreq</a>, 338Previous: <a rel="previous" accesskey="p" href="#ntpd-ipv6">ntpd ipv6</a>, 339Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 340<br> 341</div> 342 343<h4 class="subsection">authreq option (-a)</h4> 344 345<p><a name="index-ntpd_002dauthreq-6"></a> 346This is the “require crypto authentication” option. 347 348<p class="noindent">This option has some usage constraints. It: 349 <ul> 350<li>must not appear in combination with any of the following options: 351authnoreq. 352</ul> 353 354 <p>Require cryptographic authentication for broadcast client, 355multicast client and symmetric passive associations. 356This is the default. 357<div class="node"> 358<p><hr> 359<a name="ntpd-authnoreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-configfile">ntpd configfile</a>, 360Previous: <a rel="previous" accesskey="p" href="#ntpd-authreq">ntpd authreq</a>, 361Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 362<br> 363</div> 364 365<h4 class="subsection">authnoreq option (-A)</h4> 366 367<p><a name="index-ntpd_002dauthnoreq-7"></a> 368This is the “do not require crypto authentication” option. 369 370<p class="noindent">This option has some usage constraints. It: 371 <ul> 372<li>must not appear in combination with any of the following options: 373authreq. 374</ul> 375 376 <p>Do not require cryptographic authentication for broadcast client, 377multicast client and symmetric passive associations. 378This is almost never a good idea. 379<div class="node"> 380<p><hr> 381<a name="ntpd-configfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-driftfile">ntpd driftfile</a>, 382Previous: <a rel="previous" accesskey="p" href="#ntpd-authnoreq">ntpd authnoreq</a>, 383Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 384<br> 385</div> 386 387<h4 class="subsection">configfile option (-c)</h4> 388 389<p><a name="index-ntpd_002dconfigfile-8"></a> 390This is the “configuration file name” option. 391This option takes a string argument. 392The name and path of the configuration file, 393<span class="file">/etc/ntp.conf</span> 394by default. 395<div class="node"> 396<p><hr> 397<a name="ntpd-driftfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-panicgate">ntpd panicgate</a>, 398Previous: <a rel="previous" accesskey="p" href="#ntpd-configfile">ntpd configfile</a>, 399Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 400<br> 401</div> 402 403<h4 class="subsection">driftfile option (-f)</h4> 404 405<p><a name="index-ntpd_002ddriftfile-9"></a> 406This is the “frequency drift file name” option. 407This option takes a string argument. 408The name and path of the frequency file, 409<span class="file">/etc/ntp.drift</span> 410by default. 411This is the same operation as the 412<code>driftfile</code> <kbd>driftfile</kbd> 413configuration specification in the 414<span class="file">/etc/ntp.conf</span> 415file. 416<div class="node"> 417<p><hr> 418<a name="ntpd-panicgate"></a>Next: <a rel="next" accesskey="n" href="#ntpd-force_002dstep_002donce">ntpd force-step-once</a>, 419Previous: <a rel="previous" accesskey="p" href="#ntpd-driftfile">ntpd driftfile</a>, 420Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 421<br> 422</div> 423 424<h4 class="subsection">panicgate option (-g)</h4> 425 426<p><a name="index-ntpd_002dpanicgate-10"></a> 427This is the “allow the first adjustment to be big” option. 428 429<p class="noindent">This option has some usage constraints. It: 430 <ul> 431<li>may appear an unlimited number of times. 432</ul> 433 434 <p>Normally, 435<code>ntpd</code> 436exits with a message to the system log if the offset exceeds the panic threshold, which is 1000 s by default. This option allows the time to be set to any value without restriction; however, this can happen only once. If the threshold is exceeded after that, 437<code>ntpd</code> 438will exit with a message to the system log. This option can be used with the 439<code>-q</code> 440and 441<code>-x</code> 442options. 443See the 444<code>tinker</code> 445configuration file directive for other options. 446<div class="node"> 447<p><hr> 448<a name="ntpd-force_002dstep_002donce"></a>Next: <a rel="next" accesskey="n" href="#ntpd-jaildir">ntpd jaildir</a>, 449Previous: <a rel="previous" accesskey="p" href="#ntpd-panicgate">ntpd panicgate</a>, 450Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 451<br> 452</div> 453 454<h4 class="subsection">force-step-once option (-G)</h4> 455 456<p><a name="index-ntpd_002dforce_002dstep_002donce-11"></a> 457This is the “step any initial offset correction.” option. 458Normally, 459<code>ntpd</code> 460steps the time if the time offset exceeds the step threshold, 461which is 128 ms by default, and otherwise slews the time. 462This option forces the initial offset correction to be stepped, 463so the highest time accuracy can be achieved quickly. 464However, this may also cause the time to be stepped back 465so this option must not be used if 466applications requiring monotonic time are running. 467See the <code>tinker</code> configuration file directive for other options. 468<div class="node"> 469<p><hr> 470<a name="ntpd-jaildir"></a>Next: <a rel="next" accesskey="n" href="#ntpd-interface">ntpd interface</a>, 471Previous: <a rel="previous" accesskey="p" href="#ntpd-force_002dstep_002donce">ntpd force-step-once</a>, 472Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 473<br> 474</div> 475 476<h4 class="subsection">jaildir option (-i)</h4> 477 478<p><a name="index-ntpd_002djaildir-12"></a> 479This is the “jail directory” option. 480This option takes a string argument. 481 482<p class="noindent">This option has some usage constraints. It: 483 <ul> 484<li>must be compiled in by defining <code>HAVE_DROPROOT</code> during the compilation. 485</ul> 486 487 <p>Chroot the server to the directory 488<kbd>jaildir</kbd> 489. 490This option also implies that the server attempts to drop root privileges at startup. 491You may need to also specify a 492<code>-u</code> 493option. 494This option is only available if the OS supports adjusting the clock 495without full root privileges. 496This option is supported under NetBSD (configure with 497<code>--enable-clockctl</code>) or Linux (configure with 498<code>--enable-linuxcaps</code>) or Solaris (configure with <code>--enable-solarisprivs</code>). 499<div class="node"> 500<p><hr> 501<a name="ntpd-interface"></a>Next: <a rel="next" accesskey="n" href="#ntpd-keyfile">ntpd keyfile</a>, 502Previous: <a rel="previous" accesskey="p" href="#ntpd-jaildir">ntpd jaildir</a>, 503Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 504<br> 505</div> 506 507<h4 class="subsection">interface option (-I)</h4> 508 509<p><a name="index-ntpd_002dinterface-13"></a> 510This is the “listen on an interface name or address” option. 511This option takes a string argument <span class="file">iface</span>. 512 513<p class="noindent">This option has some usage constraints. It: 514 <ul> 515<li>may appear an unlimited number of times. 516</ul> 517 518 <p>Open the network address given, or all the addresses associated with the 519given interface name. This option may appear multiple times. This option 520also implies not opening other addresses, except wildcard and localhost. 521This option is deprecated. Please consider using the configuration file 522<code>interface</code> command, which is more versatile. 523<div class="node"> 524<p><hr> 525<a name="ntpd-keyfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-logfile">ntpd logfile</a>, 526Previous: <a rel="previous" accesskey="p" href="#ntpd-interface">ntpd interface</a>, 527Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 528<br> 529</div> 530 531<h4 class="subsection">keyfile option (-k)</h4> 532 533<p><a name="index-ntpd_002dkeyfile-14"></a> 534This is the “path to symmetric keys” option. 535This option takes a string argument. 536Specify the name and path of the symmetric key file. 537<span class="file">/etc/ntp.keys</span> 538is the default. 539This is the same operation as the 540<code>keys</code> <kbd>keyfile</kbd> 541configuration file directive. 542<div class="node"> 543<p><hr> 544<a name="ntpd-logfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-novirtualips">ntpd novirtualips</a>, 545Previous: <a rel="previous" accesskey="p" href="#ntpd-keyfile">ntpd keyfile</a>, 546Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 547<br> 548</div> 549 550<h4 class="subsection">logfile option (-l)</h4> 551 552<p><a name="index-ntpd_002dlogfile-15"></a> 553This is the “path to the log file” option. 554This option takes a string argument. 555Specify the name and path of the log file. 556The default is the system log file. 557This is the same operation as the 558<code>logfile</code> <kbd>logfile</kbd> 559configuration file directive. 560<div class="node"> 561<p><hr> 562<a name="ntpd-novirtualips"></a>Next: <a rel="next" accesskey="n" href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>, 563Previous: <a rel="previous" accesskey="p" href="#ntpd-logfile">ntpd logfile</a>, 564Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 565<br> 566</div> 567 568<h4 class="subsection">novirtualips option (-L)</h4> 569 570<p><a name="index-ntpd_002dnovirtualips-16"></a> 571This is the “do not listen to virtual interfaces” option. 572Do not listen to virtual interfaces, defined as those with 573names containing a colon. This option is deprecated. Please 574consider using the configuration file <code>interface</code> command, which 575is more versatile. 576<div class="node"> 577<p><hr> 578<a name="ntpd-modifymmtimer"></a>Next: <a rel="next" accesskey="n" href="#ntpd-nice">ntpd nice</a>, 579Previous: <a rel="previous" accesskey="p" href="#ntpd-novirtualips">ntpd novirtualips</a>, 580Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 581<br> 582</div> 583 584<h4 class="subsection">modifymmtimer option (-M)</h4> 585 586<p><a name="index-ntpd_002dmodifymmtimer-17"></a> 587This is the “modify multimedia timer (windows only)” option. 588 589<p class="noindent">This option has some usage constraints. It: 590 <ul> 591<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. 592</ul> 593 594 <p>Set the Windows Multimedia Timer to highest resolution. This 595ensures the resolution does not change while ntpd is running, 596avoiding timekeeping glitches associated with changes. 597<div class="node"> 598<p><hr> 599<a name="ntpd-nice"></a>Next: <a rel="next" accesskey="n" href="#ntpd-pidfile">ntpd pidfile</a>, 600Previous: <a rel="previous" accesskey="p" href="#ntpd-modifymmtimer">ntpd modifymmtimer</a>, 601Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 602<br> 603</div> 604 605<h4 class="subsection">nice option (-N)</h4> 606 607<p><a name="index-ntpd_002dnice-18"></a> 608This is the “run at high priority” option. 609To the extent permitted by the operating system, run 610<code>ntpd</code> 611at the highest priority. 612<div class="node"> 613<p><hr> 614<a name="ntpd-pidfile"></a>Next: <a rel="next" accesskey="n" href="#ntpd-priority">ntpd priority</a>, 615Previous: <a rel="previous" accesskey="p" href="#ntpd-nice">ntpd nice</a>, 616Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 617<br> 618</div> 619 620<h4 class="subsection">pidfile option (-p)</h4> 621 622<p><a name="index-ntpd_002dpidfile-19"></a> 623This is the “path to the pid file” option. 624This option takes a string argument. 625Specify the name and path of the file used to record 626<code>ntpd</code>'s 627process ID. 628This is the same operation as the 629<code>pidfile</code> <kbd>pidfile</kbd> 630configuration file directive. 631<div class="node"> 632<p><hr> 633<a name="ntpd-priority"></a>Next: <a rel="next" accesskey="n" href="#ntpd-quit">ntpd quit</a>, 634Previous: <a rel="previous" accesskey="p" href="#ntpd-pidfile">ntpd pidfile</a>, 635Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 636<br> 637</div> 638 639<h4 class="subsection">priority option (-P)</h4> 640 641<p><a name="index-ntpd_002dpriority-20"></a> 642This is the “process priority” option. 643This option takes a number argument. 644To the extent permitted by the operating system, run 645<code>ntpd</code> 646at the specified 647<code>sched_setscheduler(SCHED_FIFO)</code> 648priority. 649<div class="node"> 650<p><hr> 651<a name="ntpd-quit"></a>Next: <a rel="next" accesskey="n" href="#ntpd-propagationdelay">ntpd propagationdelay</a>, 652Previous: <a rel="previous" accesskey="p" href="#ntpd-priority">ntpd priority</a>, 653Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 654<br> 655</div> 656 657<h4 class="subsection">quit option (-q)</h4> 658 659<p><a name="index-ntpd_002dquit-21"></a> 660This is the “set the time and quit” option. 661 662<p class="noindent">This option has some usage constraints. It: 663 <ul> 664<li>must not appear in combination with any of the following options: 665saveconfigquit, wait-sync. 666</ul> 667 668 <p><code>ntpd</code> 669will not daemonize and will exit after the clock is first 670synchronized. This behavior mimics that of the 671<code>ntpdate</code> 672program, which will soon be replaced with a shell script. 673The 674<code>-g</code> 675and 676<code>-x</code> 677options can be used with this option. 678Note: The kernel time discipline is disabled with this option. 679<div class="node"> 680<p><hr> 681<a name="ntpd-propagationdelay"></a>Next: <a rel="next" accesskey="n" href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>, 682Previous: <a rel="previous" accesskey="p" href="#ntpd-quit">ntpd quit</a>, 683Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 684<br> 685</div> 686 687<h4 class="subsection">propagationdelay option (-r)</h4> 688 689<p><a name="index-ntpd_002dpropagationdelay-22"></a> 690This is the “broadcast/propagation delay” option. 691This option takes a string argument. 692Specify the default propagation delay from the broadcast/multicast server to this client. This is necessary only if the delay cannot be computed automatically by the protocol. 693<div class="node"> 694<p><hr> 695<a name="ntpd-saveconfigquit"></a>Next: <a rel="next" accesskey="n" href="#ntpd-statsdir">ntpd statsdir</a>, 696Previous: <a rel="previous" accesskey="p" href="#ntpd-propagationdelay">ntpd propagationdelay</a>, 697Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 698<br> 699</div> 700 701<h4 class="subsection">saveconfigquit option</h4> 702 703<p><a name="index-ntpd_002dsaveconfigquit-23"></a> 704This is the “save parsed configuration and quit” option. 705This option takes a string argument. 706 707<p class="noindent">This option has some usage constraints. It: 708 <ul> 709<li>must be compiled in by defining <code>SAVECONFIG</code> during the compilation. 710<li>must not appear in combination with any of the following options: 711quit, wait-sync. 712</ul> 713 714 <p>Cause <code>ntpd</code> to parse its startup configuration file and save an 715equivalent to the given filename and exit. This option was 716designed for automated testing. 717<div class="node"> 718<p><hr> 719<a name="ntpd-statsdir"></a>Next: <a rel="next" accesskey="n" href="#ntpd-trustedkey">ntpd trustedkey</a>, 720Previous: <a rel="previous" accesskey="p" href="#ntpd-saveconfigquit">ntpd saveconfigquit</a>, 721Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 722<br> 723</div> 724 725<h4 class="subsection">statsdir option (-s)</h4> 726 727<p><a name="index-ntpd_002dstatsdir-24"></a> 728This is the “statistics file location” option. 729This option takes a string argument. 730Specify the directory path for files created by the statistics facility. 731This is the same operation as the 732<code>statsdir</code> <kbd>statsdir</kbd> 733configuration file directive. 734<div class="node"> 735<p><hr> 736<a name="ntpd-trustedkey"></a>Next: <a rel="next" accesskey="n" href="#ntpd-user">ntpd user</a>, 737Previous: <a rel="previous" accesskey="p" href="#ntpd-statsdir">ntpd statsdir</a>, 738Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 739<br> 740</div> 741 742<h4 class="subsection">trustedkey option (-t)</h4> 743 744<p><a name="index-ntpd_002dtrustedkey-25"></a> 745This is the “trusted key number” option. 746This option takes a string argument <span class="file">tkey</span>. 747 748<p class="noindent">This option has some usage constraints. It: 749 <ul> 750<li>may appear an unlimited number of times. 751</ul> 752 753 <p>Add the specified key number to the trusted key list. 754<div class="node"> 755<p><hr> 756<a name="ntpd-user"></a>Next: <a rel="next" accesskey="n" href="#ntpd-updateinterval">ntpd updateinterval</a>, 757Previous: <a rel="previous" accesskey="p" href="#ntpd-trustedkey">ntpd trustedkey</a>, 758Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 759<br> 760</div> 761 762<h4 class="subsection">user option (-u)</h4> 763 764<p><a name="index-ntpd_002duser-26"></a> 765This is the “run as userid (or userid:groupid)” option. 766This option takes a string argument. 767 768<p class="noindent">This option has some usage constraints. It: 769 <ul> 770<li>must be compiled in by defining <code>HAVE_DROPROOT</code> during the compilation. 771</ul> 772 773 <p>Specify a user, and optionally a group, to switch to. 774This option is only available if the OS supports adjusting the clock 775without full root privileges. 776This option is supported under NetBSD (configure with 777<code>--enable-clockctl</code>) or Linux (configure with 778<code>--enable-linuxcaps</code>) or Solaris (configure with <code>--enable-solarisprivs</code>). 779<div class="node"> 780<p><hr> 781<a name="ntpd-updateinterval"></a>Next: <a rel="next" accesskey="n" href="#ntpd-wait_002dsync">ntpd wait-sync</a>, 782Previous: <a rel="previous" accesskey="p" href="#ntpd-user">ntpd user</a>, 783Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 784<br> 785</div> 786 787<h4 class="subsection">updateinterval option (-U)</h4> 788 789<p><a name="index-ntpd_002dupdateinterval-27"></a> 790This is the “interval in seconds between scans for new or dropped interfaces” option. 791This option takes a number argument. 792Give the time in seconds between two scans for new or dropped interfaces. 793For systems with routing socket support the scans will be performed shortly after the interface change 794has been detected by the system. 795Use 0 to disable scanning. 60 seconds is the minimum time between scans. 796<div class="node"> 797<p><hr> 798<a name="ntpd-wait_002dsync"></a>Next: <a rel="next" accesskey="n" href="#ntpd-slew">ntpd slew</a>, 799Previous: <a rel="previous" accesskey="p" href="#ntpd-updateinterval">ntpd updateinterval</a>, 800Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 801<br> 802</div> 803 804<h4 class="subsection">wait-sync option (-w)</h4> 805 806<p><a name="index-ntpd_002dwait_002dsync-28"></a> 807This is the “seconds to wait for first clock sync” option. 808This option takes a number argument. 809 810<p class="noindent">This option has some usage constraints. It: 811 <ul> 812<li>must be compiled in by defining <code>HAVE_WORKING_FORK</code> during the compilation. 813<li>must not appear in combination with any of the following options: 814nofork, quit, saveconfigquit. 815</ul> 816 817 <p>If greater than zero, alters <code>ntpd</code>'s behavior when forking to 818daemonize. Instead of exiting with status 0 immediately after 819the fork, the parent waits up to the specified number of 820seconds for the child to first synchronize the clock. The exit 821status is zero (success) if the clock was synchronized, 822otherwise it is <code>ETIMEDOUT</code>. 823This provides the option for a script starting <code>ntpd</code> to easily 824wait for the first set of the clock before proceeding. 825<div class="node"> 826<p><hr> 827<a name="ntpd-slew"></a>Next: <a rel="next" accesskey="n" href="#ntpd-usepcc">ntpd usepcc</a>, 828Previous: <a rel="previous" accesskey="p" href="#ntpd-wait_002dsync">ntpd wait-sync</a>, 829Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 830<br> 831</div> 832 833<h4 class="subsection">slew option (-x)</h4> 834 835<p><a name="index-ntpd_002dslew-29"></a> 836This is the “slew up to 600 seconds” option. 837Normally, the time is slewed if the offset is less than the step threshold, which is 128 ms by default, and stepped if above the threshold. 838This option sets the threshold to 600 s, which is well within the accuracy window to set the clock manually. 839Note: Since the slew rate of typical Unix kernels is limited to 0.5 ms/s, each second of adjustment requires an amortization interval of 2000 s. 840Thus, an adjustment as much as 600 s will take almost 14 days to complete. 841This option can be used with the 842<code>-g</code> 843and 844<code>-q</code> 845options. 846See the 847<code>tinker</code> 848configuration file directive for other options. 849Note: The kernel time discipline is disabled with this option. 850<div class="node"> 851<p><hr> 852<a name="ntpd-usepcc"></a>Next: <a rel="next" accesskey="n" href="#ntpd-pccfreq">ntpd pccfreq</a>, 853Previous: <a rel="previous" accesskey="p" href="#ntpd-slew">ntpd slew</a>, 854Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 855<br> 856</div> 857 858<h4 class="subsection">usepcc option</h4> 859 860<p><a name="index-ntpd_002dusepcc-30"></a> 861This is the “use cpu cycle counter (windows only)” option. 862 863<p class="noindent">This option has some usage constraints. It: 864 <ul> 865<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. 866</ul> 867 868 <p>Attempt to substitute the CPU counter for <code>QueryPerformanceCounter</code>. 869The CPU counter and <code>QueryPerformanceCounter</code> are compared, and if 870they have the same frequency, the CPU counter (RDTSC on x86) is 871used directly, saving the overhead of a system call. 872<div class="node"> 873<p><hr> 874<a name="ntpd-pccfreq"></a>Next: <a rel="next" accesskey="n" href="#ntpd-mdns">ntpd mdns</a>, 875Previous: <a rel="previous" accesskey="p" href="#ntpd-usepcc">ntpd usepcc</a>, 876Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 877<br> 878</div> 879 880<h4 class="subsection">pccfreq option</h4> 881 882<p><a name="index-ntpd_002dpccfreq-31"></a> 883This is the “force cpu cycle counter use (windows only)” option. 884This option takes a string argument. 885 886<p class="noindent">This option has some usage constraints. It: 887 <ul> 888<li>must be compiled in by defining <code>SYS_WINNT</code> during the compilation. 889</ul> 890 891 <p>Force substitution the CPU counter for <code>QueryPerformanceCounter</code>. 892The CPU counter (RDTSC on x86) is used unconditionally with the 893given frequency (in Hz). 894<div class="node"> 895<p><hr> 896<a name="ntpd-mdns"></a>Next: <a rel="next" accesskey="n" href="#ntpd-config">ntpd config</a>, 897Previous: <a rel="previous" accesskey="p" href="#ntpd-pccfreq">ntpd pccfreq</a>, 898Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 899<br> 900</div> 901 902<h4 class="subsection">mdns option (-m)</h4> 903 904<p><a name="index-ntpd_002dmdns-32"></a> 905This is the “register with mdns as a ntp server” option. 906 907<p class="noindent">This option has some usage constraints. It: 908 <ul> 909<li>must be compiled in by defining <code>HAVE_DNSREGISTRATION</code> during the compilation. 910</ul> 911 912 <p>Registers as an NTP server with the local mDNS server which allows 913the server to be discovered via mDNS client lookup. 914 915<div class="node"> 916<p><hr> 917<a name="ntpd-config"></a>Next: <a rel="next" accesskey="n" href="#ntpd-exit-status">ntpd exit status</a>, 918Previous: <a rel="previous" accesskey="p" href="#ntpd-mdns">ntpd mdns</a>, 919Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 920<br> 921</div> 922 923<h4 class="subsection">presetting/configuring ntpd</h4> 924 925<p>Any option that is not marked as <i>not presettable</i> may be preset by 926loading values from environment variables named <code>NTPD</code> and <code>NTPD_<OPTION_NAME></code>. <code><OPTION_NAME></code> must be one of 927the options listed above in upper case and segmented with underscores. 928The <code>NTPD</code> variable will be tokenized and parsed like 929the command line. The remaining variables are tested for existence and their 930values are treated like option arguments. 931 932 <p>The command line options relating to configuration and/or usage help are: 933 934<h5 class="subsubheading">version (-)</h5> 935 936<p>Print the program version to standard out, optionally with licensing 937information, then exit 0. The optional argument specifies how much licensing 938detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument. 939Only the first letter of the argument is examined: 940 941 <dl> 942<dt><span class="samp">version</span><dd>Only print the version. This is the default. 943<br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms. 944<br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms. 945</dl> 946 947<div class="node"> 948<p><hr> 949<a name="ntpd-exit-status"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Usage">ntpd Usage</a>, 950Previous: <a rel="previous" accesskey="p" href="#ntpd-config">ntpd config</a>, 951Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 952<br> 953</div> 954 955<h4 class="subsection">ntpd exit status</h4> 956 957<p>One of the following exit values will be returned: 958 <dl> 959<dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution. 960<br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid. 961</dl> 962 <div class="node"> 963<p><hr> 964<a name="ntpd-Usage"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Files">ntpd Files</a>, 965Previous: <a rel="previous" accesskey="p" href="#ntpd-exit-status">ntpd exit status</a>, 966Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 967<br> 968</div> 969 970<h4 class="subsection">ntpd Usage</h4> 971 972<div class="node"> 973<p><hr> 974<a name="ntpd-Files"></a>Next: <a rel="next" accesskey="n" href="#ntpd-See-Also">ntpd See Also</a>, 975Previous: <a rel="previous" accesskey="p" href="#ntpd-Usage">ntpd Usage</a>, 976Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 977<br> 978</div> 979 980<h4 class="subsection">ntpd Files</h4> 981 982<div class="node"> 983<p><hr> 984<a name="ntpd-See-Also"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Bugs">ntpd Bugs</a>, 985Previous: <a rel="previous" accesskey="p" href="#ntpd-Files">ntpd Files</a>, 986Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 987<br> 988</div> 989 990<h4 class="subsection">ntpd See Also</h4> 991 992<div class="node"> 993<p><hr> 994<a name="ntpd-Bugs"></a>Next: <a rel="next" accesskey="n" href="#ntpd-Notes">ntpd Notes</a>, 995Previous: <a rel="previous" accesskey="p" href="#ntpd-See-Also">ntpd See Also</a>, 996Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 997<br> 998</div> 999 1000<h4 class="subsection">ntpd Bugs</h4> 1001 1002<div class="node"> 1003<p><hr> 1004<a name="ntpd-Notes"></a>Previous: <a rel="previous" accesskey="p" href="#ntpd-Bugs">ntpd Bugs</a>, 1005Up: <a rel="up" accesskey="u" href="#ntpd-Invocation">ntpd Invocation</a> 1006<br> 1007</div> 1008 1009<h4 class="subsection">ntpd Notes</h4> 1010 1011<div class="node"> 1012<p><hr> 1013<a name="Usage"></a> 1014<br> 1015</div> 1016 1017<!-- node-name, next, previous, up --> 1018<h3 class="section">Usage</h3> 1019 1020