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diff --git a/contrib/ntp/html/confopt.htm b/contrib/ntp/html/confopt.htm new file mode 100644 index 0000000..68ddf7f --- /dev/null +++ b/contrib/ntp/html/confopt.htm @@ -0,0 +1,330 @@ +<html><head><title> +Configuration Options +</title></head><body><h3> +Configuration Options +</h3><hr> + +<h4>Configuration Support</h4> + +<p>Following is a description of the configuration commands in +NTPv4. These commands have the same basic functions as in NTPv3 +and in some cases new functions and new operands. The various +modes are determined by the command keyword and the type of the +required IP address. Addresses are classed by type as (s) a +remote server or peer (IP class A, B and C), (b) the broadcast +address of a local interface, (m) a multicast address (IP class +D), or (r) a reference clock address (127.127.x.x). Note that, +while autokey and burst modes are supported by these commands, +their effect in some weird mode combinations can be meaningless +or even destructive.</p> + +<dl> + <dt><tt>peer </tt><i><tt>address</tt></i><tt> [autokey | key </tt><i><tt>key</tt></i><tt>] + [burst] [version </tt><i><tt>version</tt></i><tt>] + [prefer] [minpoll </tt><i><tt>minpoll</tt></i><tt>]</tt><i><tt> + </tt></i><tt>[maxpoll </tt><i><tt>maxpoll</tt></i><tt>]</tt></dt> + <dd> </dd> + <dt><tt>server </tt><i><tt>address</tt></i><tt> [autokey | + key </tt><i><tt>key</tt></i><tt>] [burst] [version </tt><i><tt>version</tt></i><tt>] + [prefer] [minpoll </tt><i><tt>minpoll</tt></i><tt>]</tt><i><tt> + </tt></i><tt>[maxpoll </tt><i><tt>maxpoll</tt></i><tt>]</tt></dt> + <dd> </dd> + <dt><tt>broadcast </tt><i><tt>address</tt></i><tt> [autokey | + key </tt><i><tt>key</tt></i><tt>] [burst] [version </tt><i><tt>version</tt></i><tt>] + [minpoll </tt><i><tt>minpoll</tt></i><tt>]</tt><i><tt> </tt></i><tt>[maxpoll + </tt><i><tt>maxpoll</tt></i><tt>] [ttl </tt><i><tt>ttl</tt></i><tt>]</tt></dt> + <dd> </dd> + <dt><tt>manycastclient </tt><i><tt>address</tt></i><tt> + [autokey | key </tt><i><tt>key</tt></i><tt>] [burst] + [version </tt><i><tt>version</tt></i><tt>] [minpoll </tt><i><tt>minpoll + </tt></i><tt>[maxpoll </tt><i><tt>maxpoll</tt></i><tt>] + [ttl </tt><i><tt>ttl</tt></i><tt>]</tt></dt> + <dd> </dd> + <dd>These four commands specify the time server name or + address to be used and the mode in which to operate. The <i><tt>address</tt></i><tt> + </tt>can be either a DNS name or a IP address in + dotted-quad notation. Additional information on + association behavior can be found in the <a + href="assoc.htm">Association Management</a> page.</dd> + <dd> </dd> + <dd><dl> + <dt><tt>server</tt></dt> + <dd>For type s and r addresses, this operates as the + NTPv3 server command, which mobilizes a + persistent client mode association. The <tt>server</tt> + command specifies that the local server is to + operate in client mode with the specified remote + server. In this mode, the local server can be + synchronized to the remote server, but the remote + server can never be synchronized to the local + server.</dd> + <dd> </dd> + <dt><tt>peer</tt></dt> + <dd>For type s addresses (only), this operates as the + current <tt>peer </tt>command, which mobilizes a + persistent symmetric-active mode association, + except that additional modes are available. This + command should NOT be used for type b, m or r + addresses.</dd> + <dd> </dd> + <dd>The <tt>peer</tt> command specifies that the + local server is to operate in symmetric active + mode with the remote server. In this mode, the + local server can be synchronized to the remote + server and, in addition, the remote server can be + synchronized by the local server. This is useful + in a network of servers where, depending on + various failure scenarios, either the local or + remote server may be the better source of time.</dd> + <dd> </dd> + <dt><tt>broadcast</tt></dt> + <dd>For type b and m addresses (only), this is + operates as the current NTPv3 <tt>broadcast </tt>command, + which mobilizes a persistent broadcast mode + association, except that additional modes are + available. Multiple commands can be used to + specify multiple local broadcast interfaces + (subnets) and/or multiple multicast groups. Note + that local broadcast messages go only to the + interface associated with the subnet specified, + but multicast messages go to all interfaces. In + the current implementation, the source address + used for these messages is the Unix host default + address.</dd> + <dd> </dd> + <dd>In broadcast mode, the local server sends + periodic broadcast messages to a client + population at the <i><tt>address </tt></i>specified, + which is usually the broadcast address on (one + of) the local network(s) or a multicast address + assigned to NTP. The IANA has assigned the + multicast group address 224.0.1.1 exclusively to + NTP, but other nonconflicting addresses can be + used to contain the messages within + administrative boundaries.. Ordinarily, this + specification applies only to the local server + operating as a sender; for operation as a + broadcast client, see the <tt>broadcastclient</tt> + or <tt>multicastclient</tt> commands below.</dd> + <dd> </dd> + <dt><tt>manycastclient</tt> </dt> + <dd>For type m addresses (only), this mobilizes a + manycast client-mode association for the + multicast address specified. In this case a + specific address must be supplied which matches + the address used on the <tt>manycastserver </tt>command + for the designated manycast servers. The NTP + multicast address 224.0.1.1 assigned by the IANA + should NOT be used, unless specific means are + taken to avoid spraying large areas of the + Internet with these messages and causing a + possibly massive implosion of replies at the + sender. </dd> + <dd> </dd> + <dd>The <tt>manycast </tt>command specifies that the + local server is to operate in client mode with + the remote server that are discovered as the + result of broadcast/multicast messages. The + client broadcasts a request message to the group + address associated with the specified <i><tt>address + </tt></i>and specifically enabled servers respond + to these messages. The client selects the servers + providing the best time and continues as with the + <tt>server </tt>command. The remaining servers + are discarded as if never heard.</dd> + <dd> </dd> + </dl> + </dd> + <dd>Options</dd> + <dd> </dd> + <dd><dl> + <dt><tt>autokey</tt></dt> + <dd>All packets sent to the address are to include + authentication fields encrypted using the autokey + scheme.</dd> + <dd> </dd> + <dt><tt>burst</tt></dt> + <dd>At each poll interval, send a burst of eight + packets spaced, instead of the usual one.</dd> + <dd> </dd> + <dt><tt>key </tt><i><tt>key</tt></i></dt> + <dd>All packets sent to the address are to include + authentication fields encrypted using the + specified <i>key</i> identifier, which is an + unsigned 32-bit integer less than 65536. The + default is to include no encryption field.</dd> + <dd> </dd> + <dt><tt>version </tt><i><tt>version</tt></i></dt> + <dd>Specifies the version number to be used for + outgoing NTP packets. Versions 1-4 are the + choices, with version 4 the default.</dd> + <dd> </dd> + <dt><tt>prefer</tt></dt> + <dd>Marks the server as preferred. All other things + being equal, this host will be chosen for + synchronization among a set of correctly + operating hosts. See the <a href="prefer.htm">Mitigation + Rules and the <tt>prefer</tt> Keyword </a>page + for further information.</dd> + <dd> </dd> + <dt><tt>ttl </tt><i><tt>ttl</tt></i></dt> + <dd>This option is used only with broadcast mode. It + specifies the time-to-live <i><tt>ttl</tt></i> to + use on multicast packets. Selection of the proper + value, which defaults to 127, is something of a + black art and must be coordinated with the + network administrator.</dd> + <dd> </dd> + <dt><tt>minpoll </tt><i><tt>minpoll</tt></i></dt> + <dt><tt>maxpoll </tt><i><tt>maxpoll</tt></i></dt> + <dd>These options specify the minimum and maximum + polling intervals for NTP messages, in seconds to + the power of two. The default range is 6 (64 s) + to 10 (1,024 s).The allowable range is 4 (16 s) + to 17 (36.4 h) inclusive.</dd> + <dd> </dd> + </dl> + </dd> + <dt><tt>broadcastclient</tt></dt> + <dd>This command directs the local server to listen for and + respond to broadcast messages received on any local + interface. Upon hearing a broadcast message for the first + time, the local server measures the nominal network delay + using a brief client/server exchange with the remote + server, then enters the broadcastclient mode, in which it + listens for and synchronizes to succeeding broadcast + messages. Note that, in order to avoid accidental or + malicious disruption in this mode, both the local and + remote servers should operate using authentication and + the same trusted key and key identifier.</dd> + <dd> </dd> + <dt><tt>multicastclient [</tt><i><tt>address</tt></i><tt>] + [...]</tt></dt> + <dd>This command directs the local server to listen for + multicast messages at the group address(es) of the global + network. The default address is that assigned by the + Numbers Czar to NTP (224.0.1.1). This command operates in + the same way as the <tt>broadcastclient</tt> command, but + uses IP multicasting. Support for this command requires a + multicast kernel.</dd> + <dd> </dd> + <dt><tt>driftfile </tt><i><tt>driftfile</tt></i></dt> + <dd>This command specifies the name of the file used to + record the frequency offset of the local clock + oscillator. If the file exists, it is read at startup in + order to set the initial frequency offset and then + updated once per hour with the current frequency offset + computed by the daemon. If the file does not exist or + this command is not given, the initial frequency offset + is assumed zero. In this case, it may take some hours for + the frequency to stabilize and the residual timing errors + to subside.</dd> + <dd> </dd> + <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. This implies that <tt>ntpd</tt> must have + write permission for the directory the drift file is + located in, and that file system links, symbolic or + otherwise, should be avoided.</dd> + <dd> </dd> + <dt><tt>manycastserver </tt><i><tt>address </tt></i><tt>[...]</tt></dt> + <dd>This command directs the local server to listen for and + respond to broadcast messages received on any local + interface, and in addition enables the server to respond + to client mode messages to the multicast group + address(es) (type m) specified. At least one address is + required, but The NTP multicast address 224.0.1.1 + assigned by the IANA should NOT be used, unless specific + means are taken to limit the span of the reply and avoid + a possibly massive implosion at the original sender.</dd> + <dd> </dd> + <dt><tt>revoke [</tt><i><tt>logsec</tt></i><tt>]</tt> </dt> + <dd>Specifies the interval between recomputations of the + private value used with the autokey feature, which + ordinarily requires an expensive public- key computation. + The default value is 12 (65,536 s or about 18 hours). For + poll intervals above the specified interval, a new + private value will be recomputed for every message sent.</dd> + <dd> </dd> + <dt><tt>autokey [</tt><i><tt>logsec</tt></i><tt>]</tt> </dt> + <dd>Specifies the interval between regenerations of the + session key list used with the autokey feature. Note that + the size of the key list for each association depends on + this interval and the current poll interval. The default + value is 12 (4096 s or about 1.1 hours). For poll + intervals above the specified interval, a session key + list with a single entry will be regenerated for every + message sent.</dd> + <dd> </dd> + <dt><tt>enable [auth | bclient | kernel | monitor | ntp | + stats]</tt></dt> + <dt><tt>disable [auth | bclient | kernel | monitor | ntp | + stats</tt><font face="Courier New">] </font></dt> + <dd>Provides a way to enable or disable various server + options. Flags not mentioned are unaffected. Note that + all of these flags can be controlled remotely using the <a + href="ntpdc.htm"><tt>ntpdc</tt></a> utility program.</dd> + <dd> </dd> + <dd><dl> + <dt><tt>auth</tt></dt> + <dd>Enables the server to synchronize with + unconfigured peers only if the peer has been + correctly authenticated using a trusted key and + key identifier. The default for this flag is + enable.</dd> + <dd> </dd> + <dt><tt>bclient</tt></dt> + <dd>When enabled, this is identical to the <tt>broadcastclient</tt> + command. The default for this flag is disable.</dd> + <dd> </dd> + <dt><tt>kernel</tt></dt> + <dd>Enables the precision-time kernel support for the + <tt>ntp_adjtime()</tt> system call, if + implemented. Ordinarily, support for this routine + is detected automatically when the NTP daemon is + compiled, so it is not necessary for the user to + worry about this flag. It flag is provided + primarily so that this support can be disabled + during kernel development.</dd> + <dd> </dd> + <dt><tt>monitor</tt></dt> + <dd>Enables the monitoring facility. See the <tt>ntpdc</tt> + program and the <tt>monlist</tt> command or + further information. The default for this flag is + enable.</dd> + <dd> </dd> + <dt><tt>ntp</tt></dt> + <dd>Enables the server to adjust its local clock by + means of NTP. If disabled, the local clock + free-runs at its intrinsic time and frequency + offset. This flag is useful in case the local + clock is controlled by some other device or + protocol and NTP is used only to provide + synchronization to other clients. In this case, + the local clock driver can be used to provide + this function and also certain time variables for + error estimates and leap-indicators. See the <a + href="refclock.htm">Reference Clock Drivers </a>page + for further information. The default for this + flag is enable.</dd> + <dd> </dd> + <dt><tt>stats</tt></dt> + <dd>Enables the statistics facility. See the <a + href="monopt.htm">Monitoring Options </a>page for + further information. The default for this flag is + enable.</dd> + <dd> </dd> + </dl> + </dd> +</dl> + +<hr> + +<address> + David L. Mills (mills@udel.edu) +</address> +</body> +</html> |
