Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
.de1 NOP
.  it 1 an-trap
.  if \\n[.$] \,\\$*\/
..
.ie t \
.ds B-Font [CB]
.ds I-Font [CI]
.ds R-Font [CR]
.el \
.ds B-Font B
.ds I-Font I
.ds R-Font R
.TH ntpdc 1ntpdcman "14 Aug 2018" "4.2.8p12" "User Commands"
.\"
.\" EDIT THIS FILE WITH CAUTION (/tmp/.ag-uwaqJD/ag-GwaiID)
.\"
.\" It has been AutoGen-ed August 14, 2018 at 08:29:36 AM by AutoGen 5.18.5
.\" From the definitions ntpdc-opts.def
.\" and the template file agman-cmd.tpl
.SH NAME
\f\*[B-Font]ntpdc\fP
\- vendor-specific NTPD control program
.SH SYNOPSIS
\f\*[B-Font]ntpdc\fP
.\" Mixture of short (flag) options and long options
[\f\*[B-Font]\-flags\f[]]
[\f\*[B-Font]\-flag\f[] [\f\*[I-Font]value\f[]]]
[\f\*[B-Font]\-\-option-name\f[][[=| ]\f\*[I-Font]value\f[]]]
[ host ...]
.sp \n(Ppu
.ne 2

.SH DESCRIPTION
\f\*[B-Font]ntpdc\fP
is deprecated.
Please use
\fCntpq\f[]\fR(1ntpqmdoc)\f[] instead \- it can do everything
\f\*[B-Font]ntpdc\fP
used to do, and it does so using a much more sane interface.
.sp \n(Ppu
.ne 2

\f\*[B-Font]ntpdc\fP
is a utility program used to query
\fCntpd\f[]\fR(1ntpdmdoc)\f[]
about its
current state and to request changes in that state.
It uses NTP mode 7 control message formats described in the source code.
The program may
be run either in interactive mode or controlled using command line
arguments.
Extensive state and statistics information is available
through the
\f\*[B-Font]ntpdc\fP
interface.
In addition, nearly all the
configuration options which can be specified at startup using
ntpd's configuration file may also be specified at run time using
\f\*[B-Font]ntpdc\fP.
.SH "OPTIONS"
.TP
.NOP \f\*[B-Font]\-4\f[], \f\*[B-Font]\-\-ipv4\f[]
Force IPv4 DNS name resolution.
This option must not appear in combination with any of the following options:
ipv6.
.sp
Force DNS resolution of following host names on the command line
to the IPv4 namespace.
.TP
.NOP \f\*[B-Font]\-6\f[], \f\*[B-Font]\-\-ipv6\f[]
Force IPv6 DNS name resolution.
This option must not appear in combination with any of the following options:
ipv4.
.sp
Force DNS resolution of following host names on the command line
to the IPv6 namespace.
.TP
.NOP \f\*[B-Font]\-c\f[] \f\*[I-Font]cmd\f[], \f\*[B-Font]\-\-command\f[]=\f\*[I-Font]cmd\f[]
run a command and exit.
This option may appear an unlimited number of times.
.sp
The following argument is interpreted as an interactive format command
and is added to the list of commands to be executed on the specified
host(s).
.TP
.NOP \f\*[B-Font]\-d\f[], \f\*[B-Font]\-\-debug\-level\f[]
Increase debug verbosity level.
This option may appear an unlimited number of times.
.sp
.TP
.NOP \f\*[B-Font]\-D\f[] \f\*[I-Font]number\f[], \f\*[B-Font]\-\-set\-debug\-level\f[]=\f\*[I-Font]number\f[]
Set the debug verbosity level.
This option may appear an unlimited number of times.
This option takes an integer number as its argument.
.sp
.TP
.NOP \f\*[B-Font]\-i\f[], \f\*[B-Font]\-\-interactive\f[]
Force ntpq to operate in interactive mode.
This option must not appear in combination with any of the following options:
command, listpeers, peers, showpeers.
.sp
Force ntpq to operate in interactive mode.  Prompts will be written
to the standard output and commands read from the standard input.
.TP
.NOP \f\*[B-Font]\-l\f[], \f\*[B-Font]\-\-listpeers\f[]
Print a list of the peers.
This option must not appear in combination with any of the following options:
command.
.sp
Print a list of the peers known to the server as well as a summary of
their state. This is equivalent to the 'listpeers' interactive command.
.TP
.NOP \f\*[B-Font]\-n\f[], \f\*[B-Font]\-\-numeric\f[]
numeric host addresses.
.sp
Output all host addresses in dotted-quad numeric format rather than
converting to the canonical host names. 
.TP
.NOP \f\*[B-Font]\-p\f[], \f\*[B-Font]\-\-peers\f[]
Print a list of the peers.
This option must not appear in combination with any of the following options:
command.
.sp
Print a list of the peers known to the server as well as a summary
of their state. This is equivalent to the 'peers' interactive command.
.TP
.NOP \f\*[B-Font]\-s\f[], \f\*[B-Font]\-\-showpeers\f[]
Show a list of the peers.
This option must not appear in combination with any of the following options:
command.
.sp
Print a list of the peers known to the server as well as a summary
of their state. This is equivalent to the 'dmpeers' interactive command.
.TP
.NOP \f\*[B-Font]\-\&?\f[], \f\*[B-Font]\-\-help\f[]
Display usage information and exit.
.TP
.NOP \f\*[B-Font]\-\&!\f[], \f\*[B-Font]\-\-more-help\f[]
Pass the extended usage information through a pager.
.TP
.NOP \f\*[B-Font]\->\f[] [\f\*[I-Font]cfgfile\f[]], \f\*[B-Font]\-\-save-opts\f[] [=\f\*[I-Font]cfgfile\f[]]
Save the option state to \fIcfgfile\fP.  The default is the \fIlast\fP
configuration file listed in the \fBOPTION PRESETS\fP section, below.
The command will exit after updating the config file.
.TP
.NOP \f\*[B-Font]\-<\f[] \f\*[I-Font]cfgfile\f[], \f\*[B-Font]\-\-load-opts\f[]=\f\*[I-Font]cfgfile\f[], \f\*[B-Font]\-\-no-load-opts\f[]
Load options from \fIcfgfile\fP.
The \fIno-load-opts\fP form will disable the loading
of earlier config/rc/ini files.  \fI\-\-no-load-opts\fP is handled early,
out of order.
.TP
.NOP \f\*[B-Font]\-\-version\f[] [{\f\*[I-Font]v|c|n\f[]}]
Output version of program and exit.  The default mode is `v', a simple
version.  The `c' mode will print copyright information and `n' will
print the full copyright notice.
.PP
.SH "OPTION PRESETS"
Any option that is not marked as \fInot presettable\fP may be preset
by loading values from configuration ("RC" or ".INI") file(s) and values from
environment variables named:
.nf
  \fBNTPDC_<option-name>\fP or \fBNTPDC\fP
.fi
.ad
The environmental presets take precedence (are processed later than)
the configuration files.
The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
If any of these are directories, then the file \fI.ntprc\fP
is searched for within those directories.
.SH USAGE
If one or more request options are included on the command line
when
\f\*[B-Font]ntpdc\fP
is executed, each of the requests will be sent
to the NTP servers running on each of the hosts given as command
line arguments, or on localhost by default.
If no request options
are given,
\f\*[B-Font]ntpdc\fP
will attempt to read commands from the
standard input and execute these on the NTP server running on the
first host given on the command line, again defaulting to localhost
when no other host is specified.
The
\f\*[B-Font]ntpdc\fP
utility will prompt for
commands if the standard input is a terminal device.
.sp \n(Ppu
.ne 2

The
\f\*[B-Font]ntpdc\fP
utility uses NTP mode 7 packets to communicate with the
NTP server, and hence can be used to query any compatible server on
the network which permits it.
Note that since NTP is a UDP protocol
this communication will be somewhat unreliable, especially over
large distances in terms of network topology.
The
\f\*[B-Font]ntpdc\fP
utility makes
no attempt to retransmit requests, and will time requests out if
the remote host is not heard from within a suitable timeout
time.
.sp \n(Ppu
.ne 2

The operation of
\f\*[B-Font]ntpdc\fP
are specific to the particular
implementation of the
\fCntpd\f[]\fR(1ntpdmdoc)\f[]
daemon and can be expected to
work only with this and maybe some previous versions of the daemon.
Requests from a remote
\f\*[B-Font]ntpdc\fP
utility which affect the
state of the local server must be authenticated, which requires
both the remote program and local server share a common key and key
identifier.
.sp \n(Ppu
.ne 2

Note that in contexts where a host name is expected, a
\f\*[B-Font]\-4\f[]
qualifier preceding the host name forces DNS resolution to the IPv4 namespace,
while a
\f\*[B-Font]\-6\f[]
qualifier forces DNS resolution to the IPv6 namespace.
Specifying a command line option other than
\f\*[B-Font]\-i\f[]
or
\f\*[B-Font]\-n\f[]
will cause the specified query (queries) to be sent to
the indicated host(s) immediately.
Otherwise,
\f\*[B-Font]ntpdc\fP
will
attempt to read interactive format commands from the standard
input.
.SS "Interactive Commands"
Interactive format commands consist of a keyword followed by zero
to four arguments.
Only enough characters of the full keyword to
uniquely identify the command need be typed.
The output of a
command is normally sent to the standard output, but optionally the
output of individual commands may be sent to a file by appending a
\[oq]\&>\[cq],
followed by a file name, to the command line.
.sp \n(Ppu
.ne 2

A number of interactive format commands are executed entirely
within the
\f\*[B-Font]ntpdc\fP
utility itself and do not result in NTP
mode 7 requests being sent to a server.
These are described
following.
.TP 7
.NOP \f\*[B-Font]\&?\f[] \f\*[I-Font]command_keyword\f[]
.TP 7
.NOP \f\*[B-Font]help\f[] \f\*[I-Font]command_keyword\f[]
A
\[oq]\f\*[B-Font]\&?\f[]\[cq]
will print a list of all the command
keywords known to this incarnation of
\f\*[B-Font]ntpdc\fP.
A
\[oq]\f\*[B-Font]\&?\f[]\[cq]
followed by a command keyword will print function and usage
information about the command.
This command is probably a better
source of information about
\fCntpq\f[]\fR(1ntpqmdoc)\f[]
than this manual
page.
.TP 7
.NOP \f\*[B-Font]delay\f[] \f\*[I-Font]milliseconds\f[]
Specify a time interval to be added to timestamps included in
requests which require authentication.
This is used to enable
(unreliable) server reconfiguration over long delay network paths
or between machines whose clocks are unsynchronized.
Actually the
server does not now require timestamps in authenticated requests,
so this command may be obsolete.
.TP 7
.NOP \f\*[B-Font]host\f[] \f\*[I-Font]hostname\f[]
Set the host to which future queries will be sent.
Hostname may
be either a host name or a numeric address.
.TP 7
.NOP \f\*[B-Font]hostnames\f[] [\f\*[B-Font]yes\f[] | \f\*[B-Font]no\f[]]
If
\f\*[B-Font]yes\f[]
is specified, host names are printed in
information displays.
If
\f\*[B-Font]no\f[]
is specified, numeric
addresses are printed instead.
The default is
\f\*[B-Font]yes\f[],
unless
modified using the command line
\f\*[B-Font]\-n\f[]
switch.
.TP 7
.NOP \f\*[B-Font]keyid\f[] \f\*[I-Font]keyid\f[]
This command allows the specification of a key number to be
used to authenticate configuration requests.
This must correspond
to a key number the server has been configured to use for this
purpose.
.TP 7
.NOP \f\*[B-Font]quit\f[]
Exit
\f\*[B-Font]ntpdc\fP.
.TP 7
.NOP \f\*[B-Font]passwd\f[]
This command prompts you to type in a password (which will not
be echoed) which will be used to authenticate configuration
requests.
The password must correspond to the key configured for
use by the NTP server for this purpose if such requests are to be
successful.
.TP 7
.NOP \f\*[B-Font]timeout\f[] \f\*[I-Font]milliseconds\f[]
Specify a timeout period for responses to server queries.
The
default is about 8000 milliseconds.
Note that since
\f\*[B-Font]ntpdc\fP
retries each query once after a timeout, the total waiting time for
a timeout will be twice the timeout value set.
.PP
.SS "Control Message Commands"
Query commands result in NTP mode 7 packets containing requests for
information being sent to the server.
These are read-only commands
in that they make no modification of the server configuration
state.
.TP 7
.NOP \f\*[B-Font]listpeers\f[]
Obtains and prints a brief list of the peers for which the
server is maintaining state.
These should include all configured
peer associations as well as those peers whose stratum is such that
they are considered by the server to be possible future
synchronization candidates.
.TP 7
.NOP \f\*[B-Font]peers\f[]
Obtains a list of peers for which the server is maintaining
state, along with a summary of that state.
Summary information
includes the address of the remote peer, the local interface
address (0.0.0.0 if a local address has yet to be determined), the
stratum of the remote peer (a stratum of 16 indicates the remote
peer is unsynchronized), the polling interval, in seconds, the
reachability register, in octal, and the current estimated delay,
offset and dispersion of the peer, all in seconds.
.sp \n(Ppu
.ne 2

The character in the left margin indicates the mode this peer
entry is operating in.
A
\[oq]\&+\[cq]
denotes symmetric active, a
\[oq]\&-\[cq]
indicates symmetric passive, a
\[oq]\&=\[cq]
means the
remote server is being polled in client mode, a
\[oq]\&^\[cq]
indicates that the server is broadcasting to this address, a
\[oq]\&~\[cq]
denotes that the remote peer is sending broadcasts and a
\[oq]\&~\[cq]
denotes that the remote peer is sending broadcasts and a
\[oq]\&*\[cq]
marks the peer the server is currently synchronizing
to.
.sp \n(Ppu
.ne 2

The contents of the host field may be one of four forms.
It may
be a host name, an IP address, a reference clock implementation
name with its parameter or
\fBREFCLK\f[]\fR()\f[]
On
\f\*[B-Font]hostnames\f[]
\f\*[B-Font]no\f[]
only IP-addresses
will be displayed.
.TP 7
.NOP \f\*[B-Font]dmpeers\f[]
A slightly different peer summary list.
Identical to the output
of the
\f\*[B-Font]peers\f[]
command, except for the character in the
leftmost column.
Characters only appear beside peers which were
included in the final stage of the clock selection algorithm.
A
\[oq]\&.\[cq]
indicates that this peer was cast off in the falseticker
detection, while a
\[oq]\&+\[cq]
indicates that the peer made it
through.
A
\[oq]\&*\[cq]
denotes the peer the server is currently
synchronizing with.
.TP 7
.NOP \f\*[B-Font]showpeer\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]...\f[]]
Shows a detailed display of the current peer variables for one
or more peers.
Most of these values are described in the NTP
Version 2 specification.
.TP 7
.NOP \f\*[B-Font]pstats\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]...\f[]]
Show per-peer statistic counters associated with the specified
peer(s).
.TP 7
.NOP \f\*[B-Font]clockstat\f[] \f\*[I-Font]clock_peer_address\f[] [\f\*[I-Font]...\f[]]
Obtain and print information concerning a peer clock.
The
values obtained provide information on the setting of fudge factors
and other clock performance information.
.TP 7
.NOP \f\*[B-Font]kerninfo\f[]
Obtain and print kernel phase-lock loop operating parameters.
This information is available only if the kernel has been specially
modified for a precision timekeeping function.
.TP 7
.NOP \f\*[B-Font]loopinfo\f[] [\f\*[B-Font]oneline\f[] | \f\*[B-Font]multiline\f[]]
Print the values of selected loop filter variables.
The loop
filter is the part of NTP which deals with adjusting the local
system clock.
The
\[oq]offset\[cq]
is the last offset given to the
loop filter by the packet processing code.
The
\[oq]frequency\[cq]
is the frequency error of the local clock in parts-per-million
(ppm).
The
\[oq]time_const\[cq]
controls the stiffness of the
phase-lock loop and thus the speed at which it can adapt to
oscillator drift.
The
\[oq]watchdog timer\[cq]
value is the number
of seconds which have elapsed since the last sample offset was
given to the loop filter.
The
\f\*[B-Font]oneline\f[]
and
\f\*[B-Font]multiline\f[]
options specify the format in which this
information is to be printed, with
\f\*[B-Font]multiline\f[]
as the
default.
.TP 7
.NOP \f\*[B-Font]sysinfo\f[]
Print a variety of system state variables, i.e., state related
to the local server.
All except the last four lines are described
in the NTP Version 3 specification, RFC-1305.
.sp \n(Ppu
.ne 2

The
\[oq]system flags\[cq]
show various system flags, some of
which can be set and cleared by the
\f\*[B-Font]enable\f[]
and
\f\*[B-Font]disable\f[]
configuration commands, respectively.
These are
the
\f\*[B-Font]auth\f[],
\f\*[B-Font]bclient\f[],
\f\*[B-Font]monitor\f[],
\f\*[B-Font]pll\f[],
\f\*[B-Font]pps\f[]
and
\f\*[B-Font]stats\f[]
flags.
See the
\fCntpd\f[]\fR(1ntpdmdoc)\f[]
documentation for the meaning of these flags.
There
are two additional flags which are read only, the
\f\*[B-Font]kernel_pll\f[]
and
\f\*[B-Font]kernel_pps\f[].
These flags indicate
the synchronization status when the precision time kernel
modifications are in use.
The
\[oq]kernel_pll\[cq]
indicates that
the local clock is being disciplined by the kernel, while the
\[oq]kernel_pps\[cq]
indicates the kernel discipline is provided by the PPS
signal.
.sp \n(Ppu
.ne 2

The
\[oq]stability\[cq]
is the residual frequency error remaining
after the system frequency correction is applied and is intended for
maintenance and debugging.
In most architectures, this value will
initially decrease from as high as 500 ppm to a nominal value in
the range .01 to 0.1 ppm.
If it remains high for some time after
starting the daemon, something may be wrong with the local clock,
or the value of the kernel variable
\fIkern.clockrate.tick\f[]
may be
incorrect.
.sp \n(Ppu
.ne 2

The
\[oq]broadcastdelay\[cq]
shows the default broadcast delay,
as set by the
\f\*[B-Font]broadcastdelay\f[]
configuration command.
.sp \n(Ppu
.ne 2

The
\[oq]authdelay\[cq]
shows the default authentication delay,
as set by the
\f\*[B-Font]authdelay\f[]
configuration command.
.TP 7
.NOP \f\*[B-Font]sysstats\f[]
Print statistics counters maintained in the protocol
module.
.TP 7
.NOP \f\*[B-Font]memstats\f[]
Print statistics counters related to memory allocation
code.
.TP 7
.NOP \f\*[B-Font]iostats\f[]
Print statistics counters maintained in the input-output
module.
.TP 7
.NOP \f\*[B-Font]timerstats\f[]
Print statistics counters maintained in the timer/event queue
support code.
.TP 7
.NOP \f\*[B-Font]reslist\f[]
Obtain and print the server's restriction list.
This list is
(usually) printed in sorted order and may help to understand how
the restrictions are applied.
.TP 7
.NOP \f\*[B-Font]monlist\f[] [\f\*[I-Font]version\f[]]
Obtain and print traffic counts collected and maintained by the
monitor facility.
The version number should not normally need to be
specified.
.TP 7
.NOP \f\*[B-Font]clkbug\f[] \f\*[I-Font]clock_peer_address\f[] [\f\*[I-Font]...\f[]]
Obtain debugging information for a reference clock driver.
This
information is provided only by some clock drivers and is mostly
undecodable without a copy of the driver source in hand.
.PP
.SS "Runtime Configuration Requests"
All requests which cause state changes in the server are
authenticated by the server using a configured NTP key (the
facility can also be disabled by the server by not configuring a
key).
The key number and the corresponding key must also be made
known to
\f\*[B-Font]ntpdc\fP.
This can be done using the
\f\*[B-Font]keyid\f[]
and
\f\*[B-Font]passwd\f[]
commands, the latter of which will prompt at the terminal for a
password to use as the encryption key.
You will also be prompted
automatically for both the key number and password the first time a
command which would result in an authenticated request to the
server is given.
Authentication not only provides verification that
the requester has permission to make such changes, but also gives
an extra degree of protection again transmission errors.
.sp \n(Ppu
.ne 2

Authenticated requests always include a timestamp in the packet
data, which is included in the computation of the authentication
code.
This timestamp is compared by the server to its receive time
stamp.
If they differ by more than a small amount the request is
rejected.
This is done for two reasons.
First, it makes simple
replay attacks on the server, by someone who might be able to
overhear traffic on your LAN, much more difficult.
Second, it makes
it more difficult to request configuration changes to your server
from topologically remote hosts.
While the reconfiguration facility
will work well with a server on the local host, and may work
adequately between time-synchronized hosts on the same LAN, it will
work very poorly for more distant hosts.
As such, if reasonable
passwords are chosen, care is taken in the distribution and
protection of keys and appropriate source address restrictions are
applied, the run time reconfiguration facility should provide an
adequate level of security.
.sp \n(Ppu
.ne 2

The following commands all make authenticated requests.
.TP 7
.NOP \f\*[B-Font]addpeer\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]keyid\f[]] [\f\*[I-Font]version\f[]] [\f\*[B-Font]prefer\f[]]
Add a configured peer association at the given address and
operating in symmetric active mode.
Note that an existing
association with the same peer may be deleted when this command is
executed, or may simply be converted to conform to the new
configuration, as appropriate.
If the optional
\f\*[I-Font]keyid\f[]
is a
nonzero integer, all outgoing packets to the remote server will
have an authentication field attached encrypted with this key.
If
the value is 0 (or not given) no authentication will be done.
The
\f\*[I-Font]version\f[]
can be 1, 2 or 3 and defaults to 3.
The
\f\*[B-Font]prefer\f[]
keyword indicates a preferred peer (and thus will
be used primarily for clock synchronisation if possible).
The
preferred peer also determines the validity of the PPS signal \- if
the preferred peer is suitable for synchronisation so is the PPS
signal.
.TP 7
.NOP \f\*[B-Font]addserver\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]keyid\f[]] [\f\*[I-Font]version\f[]] [\f\*[B-Font]prefer\f[]]
Identical to the addpeer command, except that the operating
mode is client.
.TP 7
.NOP \f\*[B-Font]broadcast\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]keyid\f[]] [\f\*[I-Font]version\f[]] [\f\*[B-Font]prefer\f[]]
Identical to the addpeer command, except that the operating
mode is broadcast.
In this case a valid key identifier and key are
required.
The
\f\*[I-Font]peer_address\f[]
parameter can be the broadcast
address of the local network or a multicast group address assigned
to NTP.
If a multicast address, a multicast-capable kernel is
required.
.TP 7
.NOP \f\*[B-Font]unconfig\f[] \f\*[I-Font]peer_address\f[] [\f\*[I-Font]...\f[]]
This command causes the configured bit to be removed from the
specified peer(s).
In many cases this will cause the peer
association to be deleted.
When appropriate, however, the
association may persist in an unconfigured mode if the remote peer
is willing to continue on in this fashion.
.TP 7
.NOP \f\*[B-Font]fudge\f[] \f\*[I-Font]peer_address\f[] [\f\*[B-Font]time1\f[]] [\f\*[B-Font]time2\f[]] [\f\*[I-Font]stratum\f[]] [\f\*[I-Font]refid\f[]]
This command provides a way to set certain data for a reference
clock.
See the source listing for further information.
.TP 7
.NOP \f\*[B-Font]enable\f[] [\f\*[B-Font]auth\f[] | \f\*[B-Font]bclient\f[] | \f\*[B-Font]calibrate\f[] | \f\*[B-Font]kernel\f[] | \f\*[B-Font]monitor\f[] | \f\*[B-Font]ntp\f[] | \f\*[B-Font]pps\f[] | \f\*[B-Font]stats\f[]]
.TP 7
.NOP \f\*[B-Font]disable\f[] [\f\*[B-Font]auth\f[] | \f\*[B-Font]bclient\f[] | \f\*[B-Font]calibrate\f[] | \f\*[B-Font]kernel\f[] | \f\*[B-Font]monitor\f[] | \f\*[B-Font]ntp\f[] | \f\*[B-Font]pps\f[] | \f\*[B-Font]stats\f[]]
These commands operate in the same way as the
\f\*[B-Font]enable\f[]
and
\f\*[B-Font]disable\f[]
configuration file commands of
\fCntpd\f[]\fR(1ntpdmdoc)\f[].
.RS
.TP 7
.NOP \f\*[B-Font]auth\f[]
Enables the server to synchronize with unconfigured peers only
if the peer has been correctly authenticated using either public key
or private key cryptography.
The default for this flag is enable.
.TP 7
.NOP \f\*[B-Font]bclient\f[]
Enables the server to listen for a message from a broadcast or
multicast server, as in the multicastclient command with
default address.
The default for this flag is disable.
.TP 7
.NOP \f\*[B-Font]calibrate\f[]
Enables the calibrate feature for reference clocks.
The default for this flag is disable.
.TP 7
.NOP \f\*[B-Font]kernel\f[]
Enables the kernel time discipline, if available.
The default for this flag is enable if support is available, otherwise disable.
.TP 7
.NOP \f\*[B-Font]monitor\f[]
Enables the monitoring facility.
See the documentation here about the
\f\*[B-Font]monlist\f[]
command or further information.
The default for this flag is enable.
.TP 7
.NOP \f\*[B-Font]ntp\f[]
Enables time and frequency discipline.
In effect, this switch opens and closes the feedback loop,
which is useful for testing.
The default for this flag is enable.
.TP 7
.NOP \f\*[B-Font]pps\f[]
Enables the pulse-per-second (PPS) signal when frequency
and time is disciplined by the precision time kernel modifications.
See the
"A Kernel Model for Precision Timekeeping"
(available as part of the HTML documentation
provided in
\fI/usr/share/doc/ntp\f[])
page for further information.
The default for this flag is disable.
.TP 7
.NOP \f\*[B-Font]stats\f[]
Enables the statistics facility.
See the
\fIMonitoring\f[] \fIOptions\f[]
section of
\fCntp.conf\f[]\fR(5)\f[]
for further information.
The default for this flag is disable.
.RE
.TP 7
.NOP \f\*[B-Font]restrict\f[] \f\*[I-Font]address\f[] \f\*[I-Font]mask\f[] \f\*[I-Font]flag\f[] [\f\*[I-Font]...\f[]]
This command operates in the same way as the
\f\*[B-Font]restrict\f[]
configuration file commands of
\fCntpd\f[]\fR(1ntpdmdoc)\f[].
.TP 7
.NOP \f\*[B-Font]unrestrict\f[] \f\*[I-Font]address\f[] \f\*[I-Font]mask\f[] \f\*[I-Font]flag\f[] [\f\*[I-Font]...\f[]]
Unrestrict the matching entry from the restrict list.
.TP 7
.NOP \f\*[B-Font]delrestrict\f[] \f\*[I-Font]address\f[] \f\*[I-Font]mask\f[] [\f\*[B-Font]ntpport\f[]]
Delete the matching entry from the restrict list.
.TP 7
.NOP \f\*[B-Font]readkeys\f[]
Causes the current set of authentication keys to be purged and
a new set to be obtained by rereading the keys file (which must
have been specified in the
\fCntpd\f[]\fR(1ntpdmdoc)\f[]
configuration file).
This
allows encryption keys to be changed without restarting the
server.
.TP 7
.NOP \f\*[B-Font]trustedkey\f[] \f\*[I-Font]keyid\f[] [\f\*[I-Font]...\f[]]
.TP 7
.NOP \f\*[B-Font]untrustedkey\f[] \f\*[I-Font]keyid\f[] [\f\*[I-Font]...\f[]]
These commands operate in the same way as the
\f\*[B-Font]trustedkey\f[]
and
\f\*[B-Font]untrustedkey\f[]
configuration file
commands of
\fCntpd\f[]\fR(1ntpdmdoc)\f[].
.TP 7
.NOP \f\*[B-Font]authinfo\f[]
Returns information concerning the authentication module,
including known keys and counts of encryptions and decryptions
which have been done.
.TP 7
.NOP \f\*[B-Font]traps\f[]
Display the traps set in the server.
See the source listing for
further information.
.TP 7
.NOP \f\*[B-Font]addtrap\f[] \f\*[I-Font]address\f[] [\f\*[I-Font]port\f[]] [\f\*[I-Font]interface\f[]]
Set a trap for asynchronous messages.
See the source listing
for further information.
.TP 7
.NOP \f\*[B-Font]clrtrap\f[] \f\*[I-Font]address\f[] [\f\*[I-Font]port\f[]] [\f\*[I-Font]interface\f[]]
Clear a trap for asynchronous messages.
See the source listing
for further information.
.TP 7
.NOP \f\*[B-Font]reset\f[]
Clear the statistics counters in various modules of the server.
See the source listing for further information.
.PP
.SH "ENVIRONMENT"
See \fBOPTION PRESETS\fP for configuration environment variables.
.SH "FILES"
See \fBOPTION PRESETS\fP for configuration files.
.SH "EXIT STATUS"
One of the following exit values will be returned:
.TP
.NOP 0 " (EXIT_SUCCESS)"
Successful program execution.
.TP
.NOP 1 " (EXIT_FAILURE)"
The operation failed or the command syntax was not valid.
.TP
.NOP 66 " (EX_NOINPUT)"
A specified configuration file could not be loaded.
.TP
.NOP 70 " (EX_SOFTWARE)"
libopts had an internal operational error.  Please report
it to autogen-users@lists.sourceforge.net.  Thank you.
.PP
.SH "SEE ALSO"
\fCntp.conf\f[]\fR(5)\f[],
\fCntpd\f[]\fR(1ntpdmdoc)\f[]
David L. Mills,
\fINetwork Time Protocol (Version 3)\fR,
RFC1305
.PP

.SH AUTHORS
The formatting directives in this document came from FreeBSD.
.SH "COPYRIGHT"
Copyright (C) 1992-2017 The University of Delaware and Network Time Foundation all rights reserved.
This program is released under the terms of the NTP license, <http://ntp.org/license>.
.SH BUGS
The
\f\*[B-Font]ntpdc\fP
utility is a crude hack.
Much of the information it shows is
deadly boring and could only be loved by its implementer.
The
program was designed so that new (and temporary) features were easy
to hack in, at great expense to the program's ease of use.
Despite
this, the program is occasionally useful.
.sp \n(Ppu
.ne 2

Please report bugs to http://bugs.ntp.org .
.sp \n(Ppu
.ne 2

Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
.SH "NOTES"
This manual page was \fIAutoGen\fP-erated from the \fBntpdc\fP
option definitions.