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 allsync. Thus, a minimal log configuration could look
136 like this: logconfig=syncstatus +sysevents This would just list
137 the synchronizations state of ntpd and the major system events.
138 For a simple reference server, the following minimum message
139 configuration could be useful: logconfig allsync +allclock This
140 configuration will list all clock information and synchroniza‐
141 tion information. All other events and messages about peers,
142 system events and so on is suppressed.
143 logfile logfile
145 This command specifies the location of an alternate log file to
146 be used instead of the default system syslog facility. This is
147 the same operation as the -l command line option.
148 phone dial1 dial2 ...
150 This command is used in conjunction with the ACTS modem driver
151 (type 18). The arguments consist of a maximum of 10 telephone
152 numbers used to dial USNO, NIST or European time services. The
153 Hayes command ATDT is normally prepended to the number, which
154 can contain other modem control codes as well.
155 saveconfigdir directory_path
157 Specify the directory in which to write configuration snapshots
158 requested with ntpq's saveconfig command. If saveconfigdir does
159 not appear in the configuration file, saveconfig requests are
160 rejected by ntpd.
161 setvar variable [default]
163 This command adds an additional system variable. These vari‐
164 ables can be used to distribute additional information such as
165 the access policy. If the variable of the form name = value is
166 followed by the default keyword, the variable will be listed as
167 part of the default system variables (ntpq rv command). These
168 additional variables serve informational purposes only. They
169 are not related to the protocol other that they can be listed.
170 The known protocol variables will always override any variables
171 defined via the setvar mechanism. There are three special vari‐
172 ables that contain the names of all variable of the same group.
173 The sys_var_list holds the names of all system variables. The
174 peer_var_list holds the names of all peer variables and the
175 clock_var_list holds the names of the reference clock vari‐
176 ables.
177 tinker [ allan allan | dispersion dispersion | freq freq | huffpuff
179 huffpuff | panic panic | step step | stepout stepout ]
180 This command alters certain system variables used by the clock
181 discipline algorithm. The default values of these variables
182 have been carefully optimized for a wide range of network
183 speeds and reliability expectations. Very rarely is it neces‐
184 sary to change the default values; but, some folks can't resist
185 twisting the knobs. The options are as follows:
186 allan allan
189 Spedifies the Allan intercept, which is a parameter of
190 the PLL/FLL clock discipline algorithm, in seconds with
191 default 1500 s.
192 dispersion dispersion
194 Specifies the dispersion increase rate in parts-per-
195 million (PPM) with default 15 PPM.
196 freq freq
198 Spedifies the frequency offset in parts-per-million
199 (PPM) with default the value in the frequency file.
200 huffpuff huffpuff
202 Spedifies the huff-n'-puff filter span, which deter‐
203 mines the most recent interval the algorithm will
204 search for a minimum delay. The lower limit is 900 s
205 (15 m), but a more reasonable value is 7200 (2 hours).
206 panic panic
208 Spedifies the panic threshold in seconds with default
209 1000 s. If set to zero, the panic sanity check is dis‐
210 abled and a clock offset of any value will be accepted.
211 step step
213 Spedifies the step threshold in seconds. The default
214 without this command is 0.128 s. If set to zero, step
215 adjustments will never occur. Note: The kernel time
216 discipline is disabled if the step threshold is set to
217 zero or greater than 0.5 s.
218 stepout stepout
220 Specifies the stepout threshold in seconds. The default
221 without this command is 900 s. If set to zero, popcorn
222 spikes will not be suppressed.
223 tos [ beacon beacon | ceiling ceiling | cohort {0 | 1} | floor floor |
226 maxclock maxclock | maxdist maxdist | minclock minclock | mindist
227 mindist | minsane minsane | orphan stratum ]
228 This command alters certain system variables used by the the
229 clock selection and clustering algorithms. The default values
230 of these variables have been carefully optimized for a wide
231 range of network speeds and reliability expectations. Very
232 rarely is it necessary to change the default values; but, some
233 folks can't resist twisting the knobs. It can be used to select
234 the quality and quantity of peers used to synchronize the sys‐
235 tem clock and is most useful in dynamic server discovery
236 schemes. The options are as follows:
237 beacon beacon
240 The manycast server sends packets at intervals of 64 s
241 if less than maxclock servers are available. Otherwise,
242 it sends packets at the beacon interval in seconds. The
243 default is 3600 s. See the Automatic Server Discovery
244 page for further details.
245 ceiling ceiling
247 Specify the maximum stratum (exclusive) for acceptable
248 server packets. The default is 16. See the Automatic
249 Server Discovery page for further details.
250 cohort { 0 | 1 }
252 Specify whether (1) or whether not (0) a server packet
253 will be accepted for the same stratum as the client.
254 The default is 0. See the Automatic Server Discovery
255 page for further details.
256 floor floor
258 Specify the minimum stratum (inclusive) for acceptable
259 server packest. The default is 1. See the Automatic
260 Server Discovery page for further details.
261 maxclock maxclock
263 Specify the maximum number of servers retained by the
264 server discovery schemes. The default is 10. See the
265 Automatic Server Discovery page for further details.
266 maxdist maxdistance
268 Specify the synchronization distance threshold used by
269 the clock selection algorithm. The default is 1.5 s.
270 This determines both the minimum number of packets to
271 set the system clock and the maximum roundtrip delay.
272 It can be decreased to improve reliability or increased
273 to synchronize clocks on the Moon or planets.
274 minclock minclock
276 Specify the number of servers used by the clustering
277 algorithm as the minimum to include on the candidate
278 list. The default is 3. This is also the number of
279 servers to be averaged by the combining algorithm.
280 mindist mindistance
282 Specify the minimum distance used by the selection and
283 anticlockhop algorithm. Larger values increase the tol‐
284 erance for outliers; smaller values increase the selec‐
285 tivity. The default is .001 s. In some cases, such as
286 reference clocks with high jitter and a PPS signal, it
287 is useful to increase the value to insure the intersec‐
288 tion interval is always nonempty.
289 minsane minsane
291 Specify the number of servers used by the selection
292 algorithm as the minimum to set the system clock. The
293 default is 1 for legacy purposes; however, for critical
294 applications the value should be somewhat higher but
295 less than minclock.
296 orphan stratum
298 Specify the orphan stratum with default 16. If less
299 than 16 this is the stratum assumed by the root
300 servers. See the Association Management page for fur‐
301 ther details.
302 trap host_address [port port_number] [interface interfSace_address]
305 This command configures a trap receiver at the given host
306 address and port number for sending messages with the specified
307 local interface address. If the port number is unspecified, a
308 value of 18447 is used. If the interface address is not speci‐
309 fied, the message is sent with a source address of the local
310 interface the message is sent through. Note that on a multi‐
311 homed host the interface used may vary from time to time with
312 routing changes. The trap receiver will generally log event
313 messages and other information from the server in a log file.
314 While such monitor programs may also request their own trap
315 dynamically, configuring a trap receiver will ensure that no
316 messages are lost when the server is started.
317 ttl hop ...
319 This command specifies a list of TTL values in increasing
320 order. up to 8 values can be specified. In manycast mode these
321 values are used in turn in an expanding-ring search. The
322 default is eight multiples of 32 starting at 31.
323
326 ntp.conf(5)
327 HTML documentation in ntp-doc package.
329 This file was automatically generated from HTML source.
331 ntp_misc(5)