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Tue May 29 12:08:38 2012 UTC (12 years, 10 months ago) by misho
Branches: ntp, MAIN
CVS tags: v4_2_6p5p0, v4_2_6p5, HEAD

ntp 4.2.6p5

1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2: <html> 3: <head> 4: <meta http-equiv="content-type" content="text/html;charset=iso-8859-1"> 5: <meta name="generator" content="HTML Tidy, see www.w3.org"> 6: <title>Server Options</title> 7: <link href="scripts/style.css" type="text/css" rel="stylesheet"> 8: </head> 9: <body> 10: <h3>Server Options</h3> 11: <img src="pic/boom3a.gif" alt="gif" align="left"><a href="http://www.eecis.udel.edu/~mills/pictures.html">from <i>Pogo</i>, 12: Walt Kelly</a> 13: <p>The chicken is getting configuration advice.</p> 14: <p>Last update: 15: 25-Nov-2009 4:46 16: </p> 17: <br clear="left"> 18: <h4>Related Links</h4> 19: <script type="text/javascript" language="javascript" src="scripts/command.txt"></script> 20: <script type="text/javascript" language="javascript" src="scripts/confopt.txt"></script> 21: <h4>Table of Contents</h4> 22: <ul> 23: <li class="inline"><a href="#cfg">Configuration Commands</a></li> 24: <li class="inline"><a href="#opt">Command Options</a></li> 25: <li class="inline"><a href="#aux">Auxilliary Commands</a></li> 26: <li class="inline"><a href="#bug">Bugs</a></li> 27: </ul> 28: <hr> 29: <p>Following is a description of the configuration commands in NTPv4. There are 30: two classes of commands, configuration commands that configure an association 31: with a remote server, peer or reference clock, and auxilliary commands that 32: specify environmental variables that control various related operations. </p> 33: <p>The various modes described on the <a href="assoc.html">Association Management</a> page 34: are determined by the command keyword and the DNS name or IP address. Addresses 35: are classed by type as (s) a remote server or peer (IPv4 class A, B and C), 36: (b) the IP broadcast address of a local interface, (m) a multicast address (IPv4 37: class D), or (r) a reference clock address (127.127.x.x). For type m addresses 38: the IANA has assigned the multicast group address IPv4 224.0.1.1 and IPv6 ff05::101 39: (site local) exclusively to NTP, but other nonconflicting addresses can be used. </p> 40: <p>If the Basic Socket Interface Extensions for IPv6 (RFC-2553) is detected, 41: support for the IPv6 address family is generated in addition to the default 42: IPv4 address family. IPv6 addresses can be identified by the presence of colons ":" in 43: the address field. IPv6 addresses can be used almost everywhere where IPv4 addresses 44: can be used, with the exception of reference clock addresses, which are always 45: IPv4. Note that in contexts where a host name is expected, a <tt>-4</tt> qualifier 46: preceding the host name forces DNS resolution to the IPv4 namespace, while a <tt>-6</tt> qualifier 47: forces DNS resolution to the IPv6 namespace.</p> 48: <h4 id="cfg">Configuration Commands</h4> 49: <dl> 50: <dt id="server"><tt>server <i>address</i> [options ...]</tt><br> 51: <tt>peer <i>address</i> [options ...]</tt><br> 52: <tt>broadcast <i>address</i> [options ...]</tt><br> 53: <tt>manycastclient <i>address</i> [options ...]</tt><br> 54: <tt>pool <i>address</i> [options ...]</tt><br> 55: <tt>unpeer [<i>address</i> | <i>associd</i>]</tt></dt> 56: <dd>These commands specify the time server name or address to be used and the 57: mode in which to operate. The <i>address</i> can be either a DNS name or a 58: IPv4 or IPv6 address in standard notation. In general, multiple commands of 59: each type can be used for different server and peer addresses or multicast 60: groups. 61: <dl> 62: <dt><tt>server</tt></dt> 63: <dd>For type s and r addresses (only), this command mobilizes a persistent 64: client mode association with the specified remote server or local reference 65: clock. If the <tt>preempt</tt> flag is specified, a preemptable client mode 66: association is mobilized instead.</dd> 67: <dt><tt>peer</tt></dt> 68: <dd>For type s addresses (only), this command mobilizes a persistent symmetric-active 69: mode association with the specified remote peer.</dd> 70: <dt><tt>broadcast</tt></dt> 71: <dd>For type b and m addressees (only), this command mobilizes a persistent 72: broadcast or multicast server mode association. Note that type 73: b messages go only to the interface specified, but type m messages go to 74: all interfaces.</dd> 75: <dt><tt>manycastclient</tt></dt> 76: <dd>For type m addresses (only), this command mobilizes a manycast client 77: mode association for the multicast group address specified. In this mode 78: the address must match the address specified on the <tt>manycastserver</tt> command 79: of one or more designated manycast servers.</dd> 80: <dt><tt>pool</tt></dt> 81: <dd>For type s messages (only) this command mobilizes a client mode association 82: for servers implementing the pool automatic server discovery scheme described 83: on the <a href="assoc.html">Association Management</a> page. The address 84: is a DNS name in the form <tt><i>area</i>.pool.ntp.org</tt>, where <tt><i>area</i></tt> is 85: a qualifier designating the server geographic area such as <tt>us</tt> or <tt>europe</tt>.</dd> 86: <dt><tt>unpeer</tt></dt> 87: <dd>This command removes a previously configured association. An address or association ID can 88: be used to identify the association. Either an IP address or DNS name can be used. This 89: command is most useful when supplied via <tt><a href="ntpq.html">ntpq</a></tt> runtime 90: configuration commands <tt>:config</tt> and <tt>config-from-file</tt>.</dd> 91: </dl></dd> 92: </dl> 93: <h4 id="opt">Command Options</h4> 94: <dl> 95: <dt><tt>autokey</tt></dt> 96: <dd>Send and receive packets authenticated by the Autokey scheme described 97: in the <a href="authopt.html">Authentication Options</a> page. This option 98: is mutually exclusive with the <tt>key</tt> option.</dd> 99: <dt><tt>burst</tt></dt> 100: <dd>When the server is reachable, send a burst of eight packets instead of the 101: usual one. The packet spacing is normally 2 s; however, the spacing between 102: the first and second packets can be changed with the <a href="miscopt.html"><tt>calldelay</tt></a> command 103: to allow additional time for a modem or ISDN call to complete. This option 104: is valid only with the <tt>server</tt> command and type s addressesa. 105: It is a recommended option when the <tt>maxpoll</tt> option is greater than 106: 10 (1024 s).</dd> 107: <dt><tt>iburst</tt></dt> 108: <dd>When the server is unreachable, send a burst of eight packets instead of 109: the usual one. The packet spacing is normally 2 s; however, the spacing between 110: the first and second packets can be changed with the <a href="miscopt.html"><tt>calldelay</tt></a> command 111: to allow additional time for a modem or ISDN call to complete. This option 112: is valid only with the <tt>server</tt> command and type s addresses. It is 113: a recommended option with this command.</dd> 114: <dt><tt>key</tt> <i><tt>key</tt></i></dt> 115: <dd>Send and receive packets authenticated by the symmetric key scheme described 116: in the <a href="authopt.html">Authentication Options</a> page. 117: The <i><tt>key</tt></i> specifies the key identifier with values from 1 to 118: 65534, inclusive. This option is mutually exclusive with the <tt>autokey</tt> option.</dd> 119: <dt><tt>minpoll <i>minpoll<br> 120: </i></tt><tt>maxpoll <i>maxpoll</i></tt></dt> 121: <dd>These options specify the minimum and maximum poll intervals for NTP messages, 122: in seconds as a power of two. The maximum poll interval defaults to 10 123: (1024 s), but can be increased by the <tt>maxpoll</tt> option to an upper limit 124: of 17 (36 h). The minimum poll interval defaults to 6 (64 s), but can 125: be decreased by the <tt>minpoll</tt> option to a lower limit of 3 (8 s).</dd> 126: <dt><tt>mode <i>option</i></tt></dt> 127: <dd>Pass the <tt><i>option</i></tt> to a reference clock driver, where <tt><i>option</i></tt> is 128: an integer in the range from 0 to 255, inclusive. This option is valid 129: only with type r addresses.</dd> 130: <dt><tt>noselect</tt></dt> 131: <dd>Marks the server or peer to be ignored by the selection algorithm but visible 132: to the monitoring program. This option is ignored with the <tt>broadcast</tt> command.</dd> 133: <dt><tt>preempt</tt></dt> 134: <dd>Specifies the association as preemptable rather than the default persistent. 135: This option is ignored with the <tt>broadcast</tt> command and is most useful 136: with the <tt>manycastclient</tt> and <tt>pool</tt> commands.</dd> 137: <dt><tt>prefer</tt></dt> 138: <dd>Mark the server as preferred. All other things being equal, this host will 139: be chosen for synchronization among a set of correctly operating hosts. See 140: the <a href="prefer.html">Mitigation Rules and the <tt>prefer</tt> Keyword</a> page 141: for further information. This option is valid only with the <tt>server</tt> and <tt>peer</tt> commands.</dd> 142: <dt><tt>true</tt></dt> 143: <dd>Mark the association to assume truechimer status; that is, always survive 144: the selection and clustering algorithms. This option can be used with any association, 145: but is most useful for reference clocks with large jitter on the serial port 146: and precision pulse-per-second (PPS) signals. Caution: this option defeats 147: the algorithms designed to cast out falsetickers and can allow these sources 148: to set the system clock. This option is valid only with the <tt>server</tt> and <tt>peer</tt> commands.</dd> 149: <dt><tt>ttl <i>ttl</i></tt></dt> 150: <dd>This option specifies the time-to-live <i><tt>ttl</tt></i> for the <tt>broadcast</tt> command 151: and the maximum <i><tt>ttl</tt></i> for the expanding ring search used by the <tt>manycastclient</tt> command. 152: Selection of the proper value, which defaults to 127, is something of a black art and should be coordinated with the network administrator. This option is invalid with type r addresses.</dd> 153: <dt><tt>version <i>version</i></tt></dt> 154: <dd>Specifies the version number to be used f 155: or outgoing NTP packets. Versions 156: 1-4 are the choices, with version 4 the default.</dd> 157: <dt><tt>xleave</tt></dt> 158: <dd>Operate in interleaved mode (symmetric and broadcast modes only). (see <a href="xleave.html">NTP 159: Interleaved Modes</a>)</dd> 160: </dl> 161: <h4 id="aux">Auxilliary Commands</h4> 162: <dl> 163: <dt id="broadcastclient"><tt>broadcastclient</tt></dt> 164: <dd>Enable reception of broadcast server messages to any local interface (type 165: b address). Ordinarily, upon receiving a broadcast message for the first 166: time, the broadcast client measures the nominal server propagation delay using 167: a brief client/server exchange, after which it continues in listen-only mode. 168: If a nonzero value is specified in the <tt>broadcastdelay</tt> command, the 169: value becomes the delay and the volley is not executed. Note: the <tt>novolley</tt> option 170: has been deprecated for future enhancements. Note that, in order to avoid 171: accidental or malicious disruption in this mode, both the server and client 172: should operate using symmetric key or public key authentication as described 173: in the <a href="authopt.html">Authentication 174: Options</a> page. Note that the <tt>novolley</tt> keyword is incompatible with 175: public key authentication.</dd> 176: <dt id="manycastserver"><tt>manycastserver <i>address</i> [...]</tt></dt> 177: <dd>Enable reception of manycast client messages (type m)to the multicast group 178: address(es) (type m) specified. At least one address is required. Note that, 179: in order to avoid accidental or malicious disruption, both the server and client 180: should operate using symmetric key or public key authentication as described 181: in the <a href="authopt.html">Authentication Options</a> page.</dd> 182: <dt id="multicastclient"><tt>multicastclient <i>address</i> [...]</tt></dt> 183: <dd>Enable reception of multicast server messages to the multicast group address(es) 184: (type m) specified. Upon receiving a message for the first time, the multicast 185: client measures the nominal server propagation delay using a brief client/server 186: exchange with the server, then enters the broadcast client mode, in which it 187: synchronizes to succeeding multicast messages. Note that, in order to avoid 188: accidental or malicious disruption in this mode, both the server and client 189: should operate using symmetric key or public key authentication as described 190: in the <a href="authopt.html">Authentication Options</a> page.</dd> 191: </dl> 192: <h4 id="bug">Bugs</h4> 193: <p>The syntax checking is not picky; some combinations of ridiculous and even 194: hilarious options and modes may not be detected.</p> 195: <hr> 196: <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 197: </body> 198: </html>