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 | stepback step | stepfwd step |
181 stepout stepout ]
182 This command alters certain system variables used by the clock
183 discipline algorithm. The default values of these variables
184 have been carefully optimized for a wide range of network
185 speeds and reliability expectations. Very rarely is it neces‐
186 sary to change the default values; but, some folks can't resist
187 twisting the knobs. The options are as follows:
188 allan allan
191 Spedifies the Allan intercept, which is a parameter of
192 the PLL/FLL clock discipline algorithm, in seconds with
193 default 1500 s.
194 dispersion dispersion
196 Specifies the dispersion increase rate in parts-per-
197 million (PPM) with default 15 PPM.
198 freq freq
200 Spedifies the frequency offset in parts-per-million
201 (PPM) with default the value in the frequency file.
202 huffpuff huffpuff
204 Spedifies the huff-n'-puff filter span, which deter‐
205 mines the most recent interval the algorithm will
206 search for a minimum delay. The lower limit is 900 s
207 (15 m), but a more reasonable value is 7200 (2 hours).
208 panic panic
210 Spedifies the panic threshold in seconds with default
211 1000 s. If set to zero, the panic sanity check is dis‐
212 abled and a clock offset of any value will be accepted.
213 step step
215 Spedifies the step threshold in seconds. The default
216 without this command is 0.128 s. If set to zero, step
217 adjustments will never occur. Note: The kernel time
218 discipline is disabled if the step threshold is set to
219 zero or greater than 0.5 s and the threshold is applied
220 also to leap second corrections.
221 stepback step
223 Specifies the step threshold, but only in the backward
224 direction.
225 stepfwd step
227 Specifies the step threshold, but only in the forward
228 direction. To avoid problems with frequency stabiliza‐
229 tion after large slews it's not recommended to set one
230 direction to a value greater than 0.5 s without setting
231 also the other direction to at least 0.5 s.
232 stepout stepout
234 Specifies the stepout threshold in seconds. The default
235 without this command is 900 s. If set to zero, popcorn
236 spikes will not be suppressed.
237 tos [ beacon beacon | ceiling ceiling | cohort {0 | 1} | floor floor |
240 maxclock maxclock | maxdist maxdist | minclock minclock | mindist
241 mindist | minsane minsane | orphan stratum ]
242 This command alters certain system variables used by the the
243 clock selection and clustering algorithms. The default values
244 of these variables have been carefully optimized for a wide
245 range of network speeds and reliability expectations. Very
246 rarely is it necessary to change the default values; but, some
247 folks can't resist twisting the knobs. It can be used to select
248 the quality and quantity of peers used to synchronize the sys‐
249 tem clock and is most useful in dynamic server discovery
250 schemes. The options are as follows:
251 beacon beacon
254 The manycast server sends packets at intervals of 64 s
255 if less than maxclock servers are available. Otherwise,
256 it sends packets at the beacon interval in seconds. The
257 default is 3600 s. See the Automatic Server Discovery
258 page for further details.
259 ceiling ceiling
261 Specify the maximum stratum (exclusive) for acceptable
262 server packets. The default is 16. See the Automatic
263 Server Discovery page for further details.
264 cohort { 0 | 1 }
266 Specify whether (1) or whether not (0) a server packet
267 will be accepted for the same stratum as the client.
268 The default is 0. See the Automatic Server Discovery
269 page for further details.
270 floor floor
272 Specify the minimum stratum (inclusive) for acceptable
273 server packest. The default is 1. See the Automatic
274 Server Discovery page for further details.
275 maxclock maxclock
277 Specify the maximum number of servers retained by the
278 server discovery schemes. The default is 10. See the
279 Automatic Server Discovery page for further details.
280 maxdist maxdistance
282 Specify the synchronization distance threshold used by
283 the clock selection algorithm. The default is 1.5 s.
284 This determines both the minimum number of packets to
285 set the system clock and the maximum roundtrip delay.
286 It can be decreased to improve reliability or increased
287 to synchronize clocks on the Moon or planets.
288 minclock minclock
290 Specify the number of servers used by the clustering
291 algorithm as the minimum to include on the candidate
292 list. The default is 3. This is also the number of
293 servers to be averaged by the combining algorithm.
294 mindist mindistance
296 Specify the minimum distance used by the selection and
297 anticlockhop algorithm. Larger values increase the tol‐
298 erance for outliers; smaller values increase the selec‐
299 tivity. The default is .001 s. In some cases, such as
300 reference clocks with high jitter and a PPS signal, it
301 is useful to increase the value to insure the intersec‐
302 tion interval is always nonempty.
303 minsane minsane
305 Specify the number of servers used by the selection
306 algorithm as the minimum to set the system clock. The
307 default is 1 for legacy purposes; however, for critical
308 applications the value should be somewhat higher but
309 less than minclock.
310 orphan stratum
312 Specify the orphan stratum with default 16. If less
313 than 16 this is the stratum assumed by the root
314 servers. See the Association Management page for fur‐
315 ther details.
316 trap host_address [port port_number] [interface interfSace_address]
319 This command configures a trap receiver at the given host
320 address and port number for sending messages with the specified
321 local interface address. If the port number is unspecified, a
322 value of 18447 is used. If the interface address is not speci‐
323 fied, the message is sent with a source address of the local
324 interface the message is sent through. Note that on a multi‐
325 homed host the interface used may vary from time to time with
326 routing changes. The trap receiver will generally log event
327 messages and other information from the server in a log file.
328 While such monitor programs may also request their own trap
329 dynamically, configuring a trap receiver will ensure that no
330 messages are lost when the server is started.
331 ttl hop ...
333 This command specifies a list of TTL values in increasing
334 order. up to 8 values can be specified. In manycast mode these
335 values are used in turn in an expanding-ring search. The
336 default is eight multiples of 32 starting at 31.
337 dscp dscp
339 This command specifies the Differentiated Services Code Point
340 (DSCP) value that is used in sent NTP packets. The default
341 value is 48 for Class Selector 6 (CS6).
342
345 ntp.conf(5)
346 The official HTML documentation.
348 This file was automatically generated from HTML source.
350 ntp_misc(5)