1ntp_misc(5) File Formats Manual ntp_misc(5)
2
6 ntp_misc - Miscellaneous Options
7 broadcastdelay seconds
10 The broadcast and multicast modes require a special calibration
11 to determine the network delay between the local and remote
12 servers. Ordinarily, this is done automatically by the initial
13 protocol exchanges between the client and server. In some
14 cases, the calibration procedure may fail due to network or
15 server access controls, for example. This command specifies the
16 default delay to be used under these circumstances. Typically
17 (for Ethernet), a number between 0.003 and 0.007 seconds is
18 appropriate.
19 driftfile driftfile { tolerance ]
21 This command specifies the complete path and name of the file
22 used to record the frequency of the local clock oscillator.
23 This is the same operation as the -f command linke option. If
24 the file exists, it is read at startup in order to set the ini‐
25 tial frequency and then updated once per hour or more with the
26 current frequency computed by the daemon. If the file name is
27 specified, but the file itself does not exist, the starts with
28 an initial frequency of zero and creates the file when writing
29 it for the first time. If this command is not given, the daemon
30 will always start with an initial frequency of zero. The file
31 format consists of a single line containing a single floating
32 point number, which records the frequency offset measured in
33 parts-per-million (PPM). The file is updated by first writing
34 the current drift value into a temporary file and then renaming
35 this file to replace the old version. This implies that ntpd
36 must have write permission for the directory the drift file is
37 located in, and that file system links, symbolic or otherwise,
38 should be avoided. The parameter tolerance is the wander
39 threshold to skip writing the new value. If the value of wander
40 computed from recent frequency changes is greater than this
41 threshold the file will be updated once per hour. If below the
42 threshold, the file will not be written.
43 enable [ auth | bclient | calibrate | kernel | monitor | ntp | pps |
45 stats]
46 disable [ auth | bclient | calibrate | kernel | monitor | ntp | pps |
48 stats ]
49 Provides a way to enable or disable various system options.
50 Flags not mentioned are unaffected. Note that all of these
51 flags can be controlled remotely using the ntpdc utility pro‐
52 gram.
53 auth Enables the server to synchronize with unconfigured
55 peers only if the peer has been correctly authenticated
56 using either public key or private key cryptography.
57 The default for this flag is enable.
58 bclient Enables the server to listen for a message from a
60 broadcast or multicast server, as in the multicast‐
61 client command with default address. The default for
62 this flag is disable.
63 calibrate
65 Enables the calibrate feature for reference clocks. The
66 default for this flag is disable.
67 kernel Enables the kernel time discipline, if available. The
69 default for this flag is enable if support is avail‐
70 able, otherwise disable.
71 monitor Enables the monitoring facility. See the ntpdc program
73 and the monlist command or further information. The
74 default for this flag is enable.
75 ntp Enables time and frequency discipline. In effect, this
77 switch opens and closes the feedback loop, which is
78 useful for testing. The default for this flag is
79 enable.
80 stats Enables the statistics facility. See the Monitoring
82 Options page for further information. The default for
83 this flag is disable.
84 includefile includefile
87 This command allows additional configuration commands to be
88 included from a separate file. Include files may be nested to a
89 depth of five; upon reaching the end of any include file, com‐
90 mand processing resumes in the previous configuration file.
91 This option is useful for sites that run ntpd on multiple
92 hosts, with (mostly) common options (e.g., a restriction list).
93 interface [listen | ignore | drop] [all | ipv4 | ipv6 | wildcard | name
95 | address[/prefixlen]]
96 This command controls which network addresses ntpd opens, and
97 whether input is dropped without processing. The first parame‐
98 ter determines the action for addresses which match the second
99 parameter. That parameter specifies a class of addresses, or a
100 specific interface name, or an address. In the address case,
101 prefixlen determines how many bits must match for this rule to
102 apply. ignore prevents opening matching addresses, drop causes
103 ntpd to open the address and drop all received packets without
104 examination. Multiple interface commands can be used. The last
105 rule which matches a particular address determines the action
106 for it. interface commands are disabled if any -I, --interface,
107 -L, or --novirtualips command-line options are used. If none of
108 those options are used and no interface actions are specified
109 in the configuration file, all available network addresses are
110 opened. The nic command is an alias for interface.
111 leapfile leapfile
113 This command loads the NIST leapseconds file and initializes
114 the leapsecond values for the next leapsecond time, expiration
115 time and TAI offset. The file can be obtained directly from
116 NIST national time servers using ftp as the ASCII file
117 pub/leap-seconds. While not strictly a security function, the
118 Autokey protocol provides means to securely retrieve the cur‐
119 rent or updated leapsecond values from a server.
120 logconfig configkeyword
122 This command controls the amount and type of output written to
123 the system syslog facility or the alternate logfile log file.
124 All configkeyword keywords can be prefixed with =, + and -,
125 where = sets the syslogmask, + adds and - removes messages.
126 syslog messages can be controlled in four classes (clock, peer,
127 sys and sync). Within these classes four types of messages can
128 be controlled: informational messages (info), event messages
129 (events), statistics messages (statistics) and status messages
130 (status). Configuration keywords are formed by concatenating
131 the message class with the event class. The all prefix can be
132 used instead of a message class. A message class may also be
133 followed by the all keyword to enable/disable all messages of
134 the respective message class. By default, logconfig output is
135 set to =syncall +sysevents +sysstatus. Thus, a minimal log
136 configuration could look like this: logconfig =syncstatus
137 +sysevents This would just list the synchronizations state of
138 ntpd and the major system events. For a simple reference
139 server, the following minimum message configuration could be
140 useful: logconfig =syncall +clockall This configuration will
141 list all clock information and synchronization information. All
142 other events and messages about peers, system events and so on
143 is suppressed.
144 logfile logfile
146 This command specifies the location of an alternate log file to
147 be used instead of the default system syslog facility. This is
148 the same operation as the -l command line option.
149 phone dial1 dial2 ...
151 This command is used in conjunction with the ACTS modem driver
152 (type 18). The arguments consist of a maximum of 10 telephone
153 numbers used to dial USNO, NIST or European time services. The
154 Hayes command ATDT is normally prepended to the number, which
155 can contain other modem control codes as well.
156 saveconfigdir directory_path
158 Specify the directory in which to write configuration snapshots
159 requested with ntpq's saveconfig command. If saveconfigdir does
160 not appear in the configuration file, saveconfig requests are
161 rejected by ntpd.
162 setvar variable [default]
164 This command adds an additional system variable. These vari‐
165 ables can be used to distribute additional information such as
166 the access policy. If the variable of the form name = value is
167 followed by the default keyword, the variable will be listed as
168 part of the default system variables (ntpq rv command). These
169 additional variables serve informational purposes only. They
170 are not related to the protocol other that they can be listed.
171 The known protocol variables will always override any variables
172 defined via the setvar mechanism. There are three special vari‐
173 ables that contain the names of all variable of the same group.
174 The sys_var_list holds the names of all system variables. The
175 peer_var_list holds the names of all peer variables and the
176 clock_var_list holds the names of the reference clock vari‐
177 ables.
178 tinker [ allan allan | dispersion dispersion | freq freq | huffpuff
180 huffpuff | panic panic | step step | stepout stepout ]
181 This command alters certain system variables used by the clock
182 discipline algorithm. The default values of these variables
183 have been carefully optimized for a wide range of network
184 speeds and reliability expectations. Very rarely is it neces‐
185 sary to change the default values; but, some folks can't resist
186 twisting the knobs. The options are as follows:
187 allan allan
190 Spedifies the Allan intercept, which is a parameter of
191 the PLL/FLL clock discipline algorithm, in seconds with
192 default 1500 s.
193 dispersion dispersion
195 Specifies the dispersion increase rate in parts-per-
196 million (PPM) with default 15 PPM.
197 freq freq
199 Spedifies the frequency offset in parts-per-million
200 (PPM) with default the value in the frequency file.
201 huffpuff huffpuff
203 Spedifies the huff-n'-puff filter span, which deter‐
204 mines the most recent interval the algorithm will
205 search for a minimum delay. The lower limit is 900 s
206 (15 m), but a more reasonable value is 7200 (2 hours).
207 panic panic
209 Spedifies the panic threshold in seconds with default
210 1000 s. If set to zero, the panic sanity check is dis‐
211 abled and a clock offset of any value will be accepted.
212 step step
214 Spedifies the step threshold in seconds. The default
215 without this command is 0.128 s. If set to zero, step
216 adjustments will never occur. Note: The kernel time
217 discipline is disabled if the step threshold is set to
218 zero or greater than 0.5 s and the threshold is applied
219 also to leap second corrections.
220 stepout stepout
222 Specifies the stepout threshold in seconds. The default
223 without this command is 900 s. If set to zero, popcorn
224 spikes will not be suppressed.
225 tos [ beacon beacon | ceiling ceiling | cohort {0 | 1} | floor floor |
228 maxclock maxclock | maxdist maxdist | minclock minclock | mindist
229 mindist | minsane minsane | orphan stratum ]
230 This command alters certain system variables used by the the
231 clock selection and clustering algorithms. The default values
232 of these variables have been carefully optimized for a wide
233 range of network speeds and reliability expectations. Very
234 rarely is it necessary to change the default values; but, some
235 folks can't resist twisting the knobs. It can be used to select
236 the quality and quantity of peers used to synchronize the sys‐
237 tem clock and is most useful in dynamic server discovery
238 schemes. The options are as follows:
239 beacon beacon
242 The manycast server sends packets at intervals of 64 s
243 if less than maxclock servers are available. Otherwise,
244 it sends packets at the beacon interval in seconds. The
245 default is 3600 s. See the Automatic Server Discovery
246 page for further details.
247 ceiling ceiling
249 Specify the maximum stratum (exclusive) for acceptable
250 server packets. The default is 16. See the Automatic
251 Server Discovery page for further details.
252 cohort { 0 | 1 }
254 Specify whether (1) or whether not (0) a server packet
255 will be accepted for the same stratum as the client.
256 The default is 0. See the Automatic Server Discovery
257 page for further details.
258 floor floor
260 Specify the minimum stratum (inclusive) for acceptable
261 server packest. The default is 1. See the Automatic
262 Server Discovery page for further details.
263 maxclock maxclock
265 Specify the maximum number of servers retained by the
266 server discovery schemes. The default is 10. See the
267 Automatic Server Discovery page for further details.
268 maxdist maxdistance
270 Specify the synchronization distance threshold used by
271 the clock selection algorithm. The default is 1.5 s.
272 This determines both the minimum number of packets to
273 set the system clock and the maximum roundtrip delay.
274 It can be decreased to improve reliability or increased
275 to synchronize clocks on the Moon or planets.
276 minclock minclock
278 Specify the number of servers used by the clustering
279 algorithm as the minimum to include on the candidate
280 list. The default is 3. This is also the number of
281 servers to be averaged by the combining algorithm.
282 mindist mindistance
284 Specify the minimum distance used by the selection and
285 anticlockhop algorithm. Larger values increase the tol‐
286 erance for outliers; smaller values increase the selec‐
287 tivity. The default is .001 s. In some cases, such as
288 reference clocks with high jitter and a PPS signal, it
289 is useful to increase the value to insure the intersec‐
290 tion interval is always nonempty.
291 minsane minsane
293 Specify the number of servers used by the selection
294 algorithm as the minimum to set the system clock. The
295 default is 1 for legacy purposes; however, for critical
296 applications the value should be somewhat higher but
297 less than minclock.
298 orphan stratum
300 Specify the orphan stratum with default 16. If less
301 than 16 this is the stratum assumed by the root
302 servers. See the Association Management page for fur‐
303 ther details.
304 trap host_address [port port_number] [interface interfSace_address]
307 This command configures a trap receiver at the given host
308 address and port number for sending messages with the specified
309 local interface address. If the port number is unspecified, a
310 value of 18447 is used. If the interface address is not speci‐
311 fied, the message is sent with a source address of the local
312 interface the message is sent through. Note that on a multi‐
313 homed host the interface used may vary from time to time with
314 routing changes. The trap receiver will generally log event
315 messages and other information from the server in a log file.
316 While such monitor programs may also request their own trap
317 dynamically, configuring a trap receiver will ensure that no
318 messages are lost when the server is started.
319 ttl hop ...
321 This command specifies a list of TTL values in increasing
322 order. up to 8 values can be specified. In manycast mode these
323 values are used in turn in an expanding-ring search. The
324 default is eight multiples of 32 starting at 31.
325 dscp dscp
327 This command specifies the Differentiated Services Code Point
328 (DSCP) value that is used in sent NTP packets. The default
329 value is 48 for Class Selector 6 (CS6).
330
333 ntp.conf(5)
334 The official HTML documentation.
336 This file was automatically generated from HTML source.
338 ntp_misc(5)