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22 <h1 class="settitle">Ntp-keygen User's Manual</h1>
23 <div class="shortcontents">
24 <h2>Short Contents</h2>
26 <a href="#Top">Top</a>
27 <a href="#Top">NTP Key Generation Program User Manual</a>
35 <a name="Top"></a>Up: <a rel="up" accesskey="u" href="#dir">(dir)</a>
39 <h2 class="unnumbered">Top</h2>
42 <li><a accesskey="1" href="#Description">Description</a>
43 <li><a accesskey="2" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>: Invoking ntp-keygen
44 <li><a accesskey="3" href="#Running-the-Program">Running the Program</a>
45 <li><a accesskey="4" href="#Random-Seed-File">Random Seed File</a>
46 <li><a accesskey="5" href="#Cryptographic-Data-Files">Cryptographic Data Files</a>
51 <a name="Top"></a>Next: <a rel="next" accesskey="n" href="#Description">Description</a>,
52 Previous: <a rel="previous" accesskey="p" href="#dir">(dir)</a>,
53 Up: <a rel="up" accesskey="u" href="#dir">(dir)</a>
57 <h2 class="unnumbered">NTP Key Generation Program User Manual</h2>
59 <p>This document describes the use of the NTP Project's <code>ntp-keygen</code>
60 program, that generates cryptographic data files used by the NTPv4
61 authentication and identity schemes.
62 It can generate message digest keys used in symmetric key cryptography and,
63 if the OpenSSL software
64 library has been installed, it can generate host keys, sign keys,
65 certificates, and identity keys and parameters used by the Autokey
66 public key cryptography.
67 The message digest keys file is generated in a
68 format compatible with NTPv3.
69 All other files are in PEM-encoded
70 printable ASCII format so they can be embedded as MIME attachments in
73 <p>This document applies to version 4.2.8p9 of <code>ntp-keygen</code>.
77 <a name="Description"></a>Next: <a rel="next" accesskey="n" href="#Running-the-Program">Running the Program</a>,
78 Previous: <a rel="previous" accesskey="p" href="#Top">Top</a>,
79 Up: <a rel="up" accesskey="u" href="#Top">Top</a>
83 <!-- node-name, next, previous, up -->
84 <h3 class="section">Description</h3>
86 <p>This program generates cryptographic data files used by the NTPv4
87 authentication and identity schemes. It can generate message digest
88 keys used in symmetric key cryptography and, if the OpenSSL software
89 library has been installed, it can generate host keys, sign keys,
90 certificates, and identity keys and parameters used by the Autokey
91 public key cryptography. The message digest keys file is generated in a
92 format compatible with NTPv3. All other files are in PEM-encoded
93 printable ASCII format so they can be embedded as MIME attachments in
96 <p>When used to generate message digest keys, the program produces a file
97 containing ten pseudo-random printable ASCII strings suitable for the
98 MD5 message digest algorithm included in the distribution.
100 OpenSSL library is installed, it produces an additional ten hex-encoded
101 random bit strings suitable for the SHA1 and other message digest
103 The message digest keys file must be distributed and stored
104 using secure means beyond the scope of NTP itself.
106 used for ordinary NTP associations, additional keys can be defined as
107 passwords for the ntpq and ntpdc utility programs.
109 <p>The remaining generated files are compatible with other OpenSSL
110 applications and other Public Key Infrastructure (PKI) resources.
111 Certificates generated by this program are compatible with extant
112 industry practice, although some users might find the interpretation of
113 X509v3 extension fields somewhat liberal.
114 However, the identity keys
115 are probably not compatible with anything other than Autokey.
117 <p>Some files used by this program are encrypted using a private password.
118 The <code>-p</code> option specifies the password for local encrypted files and the
119 <code>-q</code> option the password for encrypted files sent to remote sites.
120 If no password is specified, the host name returned by the Unix
121 <code>gethostname()</code> function, normally the DNS name of the host, is used.
123 <p>The <kbd>pw</kbd> option of the <code>crypto</code> configuration command
124 specifies the read password for previously encrypted local files.
125 This must match the local password used by this program.
126 If not specified, the host name is used.
127 Thus, if files are generated by this program without password,
128 they can be read back by ntpd without password, but only on the same
131 <p>Normally, encrypted files for each host are generated by that host and
132 used only by that host, although exceptions exist as noted later on
134 The symmetric keys file, normally called <code>ntp.keys</code>, is
135 usually installed in <code>/etc</code>.
136 Other files and links are usually installed
137 in <code>/usr/local/etc</code>, which is normally in a shared filesystem in
138 NFS-mounted networks and cannot be changed by shared clients.
139 The location of the keys directory can be changed by the keysdir
140 configuration command in such cases.
141 Normally, this is in <code>/etc</code>.
143 <p>This program directs commentary and error messages to the standard
144 error stream <code>stderr</code> and remote files to the standard output stream
145 <code>stdout</code> where they can be piped to other applications or redirected to
147 The names used for generated files and links all begin with the
148 string <code>ntpkey</code> and include the file type,
149 generating host and filestamp,
150 as described in the <a href="#Cryptographic-Data-Files">Cryptographic Data Files</a> section below.
154 <a name="Running-the-Program"></a>Next: <a rel="next" accesskey="n" href="#Random-Seed-File">Random Seed File</a>,
155 Previous: <a rel="previous" accesskey="p" href="#Description">Description</a>,
156 Up: <a rel="up" accesskey="u" href="#Top">Top</a>
160 <!-- node-name, next, previous, up -->
161 <h3 class="section">Running the Program</h3>
163 <p>To test and gain experience with Autokey concepts, log in as root and
164 change to the keys directory, usually <code>/usr/local/etc</code>.
166 first time, or if all files with names beginning <code>ntpkey</code>] have been
167 removed, use the <code>ntp-keygen</code> command without arguments to generate a
168 default RSA host key and matching RSA-MD5 certificate with expiration
170 If run again without options, the program uses the
171 existing keys and parameters and generates only a new certificate with
172 new expiration date one year hence.
174 <p>Run the command on as many hosts as necessary.
175 Designate one of them as the trusted host (TH) using <code>ntp-keygen</code>
176 with the <code>-T</code> option and configure
177 it to synchronize from reliable Internet servers.
178 Then configure the other hosts to synchronize to the TH directly or indirectly.
179 A certificate trail is created when Autokey asks the immediately
180 ascendant host towards the TH to sign its certificate, which is then
181 provided to the immediately descendant host on request.
182 All group hosts should have acyclic certificate trails ending on the TH.
184 <p>The host key is used to encrypt the cookie when required and so must be
186 By default, the host key is also the sign key used to encrypt signatures.
187 A different sign key can be assigned using the <code>-S</code> option
188 and this can be either RSA or DSA type.
189 By default, the signature
190 message digest type is MD5, but any combination of sign key type and
191 message digest type supported by the OpenSSL library can be specified
192 using the <code>-c</code> option.
194 <p>The rules say cryptographic media should be generated with proventic
195 filestamps, which means the host should already be synchronized before
197 This of course creates a chicken-and-egg problem
198 when the host is started for the first time.
199 Accordingly, the host time
200 should be set by some other means, such as eyeball-and-wristwatch, at
201 least so that the certificate lifetime is within the current year.
202 After that and when the host is synchronized to a proventic source, the
203 certificate should be re-generated.
205 <p>Additional information on trusted groups and identity schemes is on the
206 Autokey Public-Key Authentication page.
210 <a name="ntp_002dkeygen-Invocation"></a>
214 <h3 class="section">Invoking ntp-keygen</h3>
216 <p><a name="index-ntp_002dkeygen-1"></a><a name="index-Create-a-NTP-host-key-2"></a>
218 <p>This program generates cryptographic data files used by the NTPv4
219 authentication and identification schemes.
220 It generates MD5 key files used in symmetric key cryptography.
221 In addition, if the OpenSSL software library has been installed,
222 it generates keys, certificate and identity files used in public key
224 These files are used for cookie encryption,
225 digital signature and challenge/response identification algorithms
226 compatible with the Internet standard security infrastructure.
228 <p>All files are in PEM-encoded printable ASCII format,
229 so they can be embedded as MIME attachments in mail to other sites
230 and certificate authorities.
231 By default, files are not encrypted.
233 <p>When used to generate message digest keys, the program produces a file
234 containing ten pseudo-random printable ASCII strings suitable for the
235 MD5 message digest algorithm included in the distribution.
236 If the OpenSSL library is installed, it produces an additional ten
237 hex-encoded random bit strings suitable for the SHA1 and other message
239 The message digest keys file must be distributed and stored
240 using secure means beyond the scope of NTP itself.
241 Besides the keys used for ordinary NTP associations, additional keys
242 can be defined as passwords for the
243 <code>ntpq(1ntpqmdoc)</code>
245 <code>ntpdc(1ntpdcmdoc)</code>
248 <p>The remaining generated files are compatible with other OpenSSL
249 applications and other Public Key Infrastructure (PKI) resources.
250 Certificates generated by this program are compatible with extant
251 industry practice, although some users might find the interpretation of
252 X509v3 extension fields somewhat liberal.
253 However, the identity keys are probably not compatible with anything
256 <p>Some files used by this program are encrypted using a private password.
259 option specifies the password for local encrypted files and the
261 option the password for encrypted files sent to remote sites.
262 If no password is specified, the host name returned by the Unix
263 <code>gethostname()</code>
264 function, normally the DNS name of the host is used.
270 configuration command specifies the read
271 password for previously encrypted local files.
272 This must match the local password used by this program.
273 If not specified, the host name is used.
274 Thus, if files are generated by this program without password,
275 they can be read back by
277 without password but only on the same host.
279 <p>Normally, encrypted files for each host are generated by that host and
280 used only by that host, although exceptions exist as noted later on
282 The symmetric keys file, normally called
284 is usually installed in
285 <span class="file">/etc</span>.
286 Other files and links are usually installed in
287 <span class="file">/usr/local/etc</span>,
288 which is normally in a shared filesystem in
289 NFS-mounted networks and cannot be changed by shared clients.
290 The location of the keys directory can be changed by the
292 configuration command in such cases.
294 <span class="file">/etc</span>.
296 <p>This program directs commentary and error messages to the standard
299 and remote files to the standard output stream
301 where they can be piped to other applications or redirected to files.
302 The names used for generated files and links all begin with the
305 and include the file type, generating host and filestamp,
307 Cryptographic Data Files
310 <h5 class="subsubsection">Running the Program</h5>
312 <p>To test and gain experience with Autokey concepts, log in as root and
313 change to the keys directory, usually
314 <span class="file">/usr/local/etc</span>
315 When run for the first time, or if all files with names beginning with
317 have been removed, use the
318 <code>ntp-keygen</code>
319 command without arguments to generate a
320 default RSA host key and matching RSA-MD5 certificate with expiration
322 If run again without options, the program uses the
323 existing keys and parameters and generates only a new certificate with
324 new expiration date one year hence.
326 <p>Run the command on as many hosts as necessary.
327 Designate one of them as the trusted host (TH) using
328 <code>ntp-keygen</code>
331 option and configure it to synchronize from reliable Internet servers.
332 Then configure the other hosts to synchronize to the TH directly or
334 A certificate trail is created when Autokey asks the immediately
335 ascendant host towards the TH to sign its certificate, which is then
336 provided to the immediately descendant host on request.
337 All group hosts should have acyclic certificate trails ending on the TH.
339 <p>The host key is used to encrypt the cookie when required and so must be
341 By default, the host key is also the sign key used to encrypt
343 A different sign key can be assigned using the
345 option and this can be either RSA or DSA type.
346 By default, the signature
347 message digest type is MD5, but any combination of sign key type and
348 message digest type supported by the OpenSSL library can be specified
352 The rules say cryptographic media should be generated with proventic
353 filestamps, which means the host should already be synchronized before
355 This of course creates a chicken-and-egg problem
356 when the host is started for the first time.
357 Accordingly, the host time
358 should be set by some other means, such as eyeball-and-wristwatch, at
359 least so that the certificate lifetime is within the current year.
360 After that and when the host is synchronized to a proventic source, the
361 certificate should be re-generated.
363 <p>Additional information on trusted groups and identity schemes is on the
364 Autokey Public-Key Authentication
368 <code>ntpd(1ntpdmdoc)</code>
369 configuration command
370 <code>crypto</code> <code>pw</code> <kbd>password</kbd>
371 specifies the read password for previously encrypted files.
372 The daemon expires on the spot if the password is missing
374 For convenience, if a file has been previously encrypted,
375 the default read password is the name of the host running
377 If the previous write password is specified as the host name,
378 these files can be read by that host with no explicit password.
380 <p>File names begin with the prefix
382 and end with the postfix
383 <kbd>_hostname.filestamp</kbd>,
386 is the owner name, usually the string returned
387 by the Unix gethostname() routine, and
389 is the NTP seconds when the file was generated, in decimal digits.
390 This both guarantees uniqueness and simplifies maintenance
391 procedures, since all files can be quickly removed
393 <code>rm</code> <code>ntpkey*</code>
394 command or all files generated
395 at a specific time can be removed by a
397 <kbd>*filestamp</kbd>
399 To further reduce the risk of misconfiguration,
400 the first two lines of a file contain the file name
401 and generation date and time as comments.
403 <p>All files are installed by default in the keys directory
404 <span class="file">/usr/local/etc</span>,
405 which is normally in a shared filesystem
406 in NFS-mounted networks.
407 The actual location of the keys directory
408 and each file can be overridden by configuration commands,
409 but this is not recommended.
410 Normally, the files for each host are generated by that host
411 and used only by that host, although exceptions exist
412 as noted later on this page.
414 <p>Normally, files containing private values,
415 including the host key, sign key and identification parameters,
416 are permitted root read/write-only;
417 while others containing public values are permitted world readable.
418 Alternatively, files containing private values can be encrypted
419 and these files permitted world readable,
420 which simplifies maintenance in shared file systems.
421 Since uniqueness is insured by the hostname and
422 file name extensions, the files for a NFS server and
423 dependent clients can all be installed in the same shared directory.
425 <p>The recommended practice is to keep the file name extensions
426 when installing a file and to install a soft link
427 from the generic names specified elsewhere on this page
428 to the generated files.
429 This allows new file generations to be activated simply
430 by changing the link.
431 If a link is present, ntpd follows it to the file name
432 to extract the filestamp.
433 If a link is not present,
434 <code>ntpd(1ntpdmdoc)</code>
435 extracts the filestamp from the file itself.
436 This allows clients to verify that the file and generation times
439 <code>ntp-keygen</code>
440 program uses the same timestamp extension for all files generated
441 at one time, so each generation is distinct and can be readily
442 recognized in monitoring data.
444 <h5 class="subsubsection">Running the program</h5>
446 <p>The safest way to run the
447 <code>ntp-keygen</code>
448 program is logged in directly as root.
449 The recommended procedure is change to the keys directory,
451 <span class="file">/usr/local/etc</span>,
452 then run the program.
453 When run for the first time,
456 files have been removed,
457 the program generates a RSA host key file and matching RSA-MD5 certificate file,
458 which is all that is necessary in many cases.
459 The program also generates soft links from the generic names
460 to the respective files.
461 If run again, the program uses the same host key file,
462 but generates a new certificate file and link.
464 <p>The host key is used to encrypt the cookie when required and so must be RSA type.
465 By default, the host key is also the sign key used to encrypt signatures.
466 When necessary, a different sign key can be specified and this can be
467 either RSA or DSA type.
468 By default, the message digest type is MD5, but any combination
469 of sign key type and message digest type supported by the OpenSSL library
470 can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2
471 and RIPE160 message digest algorithms.
472 However, the scheme specified in the certificate must be compatible
474 Certificates using any digest algorithm are compatible with RSA sign keys;
475 however, only SHA and SHA1 certificates are compatible with DSA sign keys.
477 <p>Private/public key files and certificates are compatible with
478 other OpenSSL applications and very likely other libraries as well.
479 Certificates or certificate requests derived from them should be compatible
480 with extant industry practice, although some users might find
481 the interpretation of X509v3 extension fields somewhat liberal.
482 However, the identification parameter files, although encoded
483 as the other files, are probably not compatible with anything other than Autokey.
485 <p>Running the program as other than root and using the Unix
488 to assume root may not work properly, since by default the OpenSSL library
489 looks for the random seed file
491 in the user home directory.
492 However, there should be only one
495 in the root directory, so it is convenient to define the
496 <code>$RANDFILE</code>
497 environment variable used by the OpenSSL library as the path to
500 <p>Installing the keys as root might not work in NFS-mounted
501 shared file systems, as NFS clients may not be able to write
502 to the shared keys directory, even as root.
503 In this case, NFS clients can specify the files in another
505 <span class="file">/etc</span>
509 There is no need for one client to read the keys and certificates
510 of other clients or servers, as these data are obtained automatically
511 by the Autokey protocol.
513 <p>Ordinarily, cryptographic files are generated by the host that uses them,
514 but it is possible for a trusted agent (TA) to generate these files
515 for other hosts; however, in such cases files should always be encrypted.
516 The subject name and trusted name default to the hostname
517 of the host generating the files, but can be changed by command line options.
518 It is convenient to designate the owner name and trusted name
519 as the subject and issuer fields, respectively, of the certificate.
520 The owner name is also used for the host and sign key files,
521 while the trusted name is used for the identity files.
523 <p>All files are installed by default in the keys directory
524 <span class="file">/usr/local/etc</span>,
525 which is normally in a shared filesystem
526 in NFS-mounted networks.
527 The actual location of the keys directory
528 and each file can be overridden by configuration commands,
529 but this is not recommended.
530 Normally, the files for each host are generated by that host
531 and used only by that host, although exceptions exist
532 as noted later on this page.
534 <p>Normally, files containing private values,
535 including the host key, sign key and identification parameters,
536 are permitted root read/write-only;
537 while others containing public values are permitted world readable.
538 Alternatively, files containing private values can be encrypted
539 and these files permitted world readable,
540 which simplifies maintenance in shared file systems.
541 Since uniqueness is insured by the hostname and
542 file name extensions, the files for a NFS server and
543 dependent clients can all be installed in the same shared directory.
545 <p>The recommended practice is to keep the file name extensions
546 when installing a file and to install a soft link
547 from the generic names specified elsewhere on this page
548 to the generated files.
549 This allows new file generations to be activated simply
550 by changing the link.
551 If a link is present, ntpd follows it to the file name
552 to extract the filestamp.
553 If a link is not present,
554 <code>ntpd(1ntpdmdoc)</code>
555 extracts the filestamp from the file itself.
556 This allows clients to verify that the file and generation times
559 <code>ntp-keygen</code>
560 program uses the same timestamp extension for all files generated
561 at one time, so each generation is distinct and can be readily
562 recognized in monitoring data.
564 <h5 class="subsubsection">Running the program</h5>
566 <p>The safest way to run the
567 <code>ntp-keygen</code>
568 program is logged in directly as root.
569 The recommended procedure is change to the keys directory,
571 <span class="file">/usr/local/etc</span>,
572 then run the program.
573 When run for the first time,
576 files have been removed,
577 the program generates a RSA host key file and matching RSA-MD5 certificate file,
578 which is all that is necessary in many cases.
579 The program also generates soft links from the generic names
580 to the respective files.
581 If run again, the program uses the same host key file,
582 but generates a new certificate file and link.
584 <p>The host key is used to encrypt the cookie when required and so must be RSA type.
585 By default, the host key is also the sign key used to encrypt signatures.
586 When necessary, a different sign key can be specified and this can be
587 either RSA or DSA type.
588 By default, the message digest type is MD5, but any combination
589 of sign key type and message digest type supported by the OpenSSL library
590 can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2
591 and RIPE160 message digest algorithms.
592 However, the scheme specified in the certificate must be compatible
594 Certificates using any digest algorithm are compatible with RSA sign keys;
595 however, only SHA and SHA1 certificates are compatible with DSA sign keys.
597 <p>Private/public key files and certificates are compatible with
598 other OpenSSL applications and very likely other libraries as well.
599 Certificates or certificate requests derived from them should be compatible
600 with extant industry practice, although some users might find
601 the interpretation of X509v3 extension fields somewhat liberal.
602 However, the identification parameter files, although encoded
603 as the other files, are probably not compatible with anything other than Autokey.
605 <p>Running the program as other than root and using the Unix
608 to assume root may not work properly, since by default the OpenSSL library
609 looks for the random seed file
611 in the user home directory.
612 However, there should be only one
615 in the root directory, so it is convenient to define the
616 <code>$RANDFILE</code>
617 environment variable used by the OpenSSL library as the path to
620 <p>Installing the keys as root might not work in NFS-mounted
621 shared file systems, as NFS clients may not be able to write
622 to the shared keys directory, even as root.
623 In this case, NFS clients can specify the files in another
625 <span class="file">/etc</span>
629 There is no need for one client to read the keys and certificates
630 of other clients or servers, as these data are obtained automatically
631 by the Autokey protocol.
633 <p>Ordinarily, cryptographic files are generated by the host that uses them,
634 but it is possible for a trusted agent (TA) to generate these files
635 for other hosts; however, in such cases files should always be encrypted.
636 The subject name and trusted name default to the hostname
637 of the host generating the files, but can be changed by command line options.
638 It is convenient to designate the owner name and trusted name
639 as the subject and issuer fields, respectively, of the certificate.
640 The owner name is also used for the host and sign key files,
641 while the trusted name is used for the identity files.
645 <p>s Trusted Hosts and Groups
646 Each cryptographic configuration involves selection of a signature scheme
647 and identification scheme, called a cryptotype,
649 <a href="#Authentication-Options">Authentication Options</a>
651 <code>ntp.conf(5)</code>.
652 The default cryptotype uses RSA encryption, MD5 message digest
653 and TC identification.
654 First, configure a NTP subnet including one or more low-stratum
655 trusted hosts from which all other hosts derive synchronization
656 directly or indirectly.
657 Trusted hosts have trusted certificates;
658 all other hosts have nontrusted certificates.
659 These hosts will automatically and dynamically build authoritative
660 certificate trails to one or more trusted hosts.
661 A trusted group is the set of all hosts that have, directly or indirectly,
662 a certificate trail ending at a trusted host.
663 The trail is defined by static configuration file entries
664 or dynamic means described on the
665 <a href="#Automatic-NTP-Configuration-Options">Automatic NTP Configuration Options</a>
667 <code>ntp.conf(5)</code>.
669 <p>On each trusted host as root, change to the keys directory.
670 To insure a fresh fileset, remove all
674 <code>ntp-keygen</code>
676 to generate keys and a trusted certificate.
677 On all other hosts do the same, but leave off the
679 flag to generate keys and nontrusted certificates.
680 When complete, start the NTP daemons beginning at the lowest stratum
681 and working up the tree.
682 It may take some time for Autokey to instantiate the certificate trails
683 throughout the subnet, but setting up the environment is completely automatic.
685 <p>If it is necessary to use a different sign key or different digest/signature
686 scheme than the default, run
687 <code>ntp-keygen</code>
689 <code>-S</code> <kbd>type</kbd>
696 The most often need to do this is when a DSA-signed certificate is used.
697 If it is necessary to use a different certificate scheme than the default,
699 <code>ntp-keygen</code>
701 <code>-c</code> <kbd>scheme</kbd>
706 <code>ntp-keygen</code>
707 is run again without these options, it generates a new certificate
708 using the same scheme and sign key.
710 <p>After setting up the environment it is advisable to update certificates
711 from time to time, if only to extend the validity interval.
713 <code>ntp-keygen</code>
714 with the same flags as before to generate new certificates
716 However, if the host or sign key is changed,
717 <code>ntpd(1ntpdmdoc)</code>
720 <code>ntpd(1ntpdmdoc)</code>
721 is restarted, it loads any new files and restarts the protocol.
722 Other dependent hosts will continue as usual until signatures are refreshed,
723 at which time the protocol is restarted.
725 <h5 class="subsubsection">Identity Schemes</h5>
727 <p>As mentioned on the Autonomous Authentication page,
728 the default TC identity scheme is vulnerable to a middleman attack.
729 However, there are more secure identity schemes available,
730 including PC, IFF, GQ and MV described on the
731 "Identification Schemes"
734 <code>http://www.eecis.udel.edu/%7emills/keygen.html</code>).
735 These schemes are based on a TA, one or more trusted hosts
736 and some number of nontrusted hosts.
737 Trusted hosts prove identity using values provided by the TA,
738 while the remaining hosts prove identity using values provided
739 by a trusted host and certificate trails that end on that host.
740 The name of a trusted host is also the name of its sugroup
741 and also the subject and issuer name on its trusted certificate.
742 The TA is not necessarily a trusted host in this sense, but often is.
744 <p>In some schemes there are separate keys for servers and clients.
745 A server can also be a client of another server,
746 but a client can never be a server for another client.
747 In general, trusted hosts and nontrusted hosts that operate
748 as both server and client have parameter files that contain
749 both server and client keys.
751 only as clients have key files that contain only client keys.
753 <p>The PC scheme supports only one trusted host in the group.
754 On trusted host alice run
755 <code>ntp-keygen</code>
757 <code>-p</code> <kbd>password</kbd>
758 to generate the host key file
759 <span class="file">ntpkey_RSAkey_</span><kbd>alice.filestamp</kbd>
760 and trusted private certificate file
761 <span class="file">ntpkey_RSA-MD5_cert_</span><kbd>alice.filestamp</kbd>.
762 Copy both files to all group hosts;
763 they replace the files which would be generated in other schemes.
764 On each host bob install a soft link from the generic name
765 <span class="file">ntpkey_host_</span><kbd>bob</kbd>
766 to the host key file and soft link
767 <span class="file">ntpkey_cert_</span><kbd>bob</kbd>
768 to the private certificate file.
769 Note the generic links are on bob, but point to files generated
770 by trusted host alice.
771 In this scheme it is not possible to refresh
772 either the keys or certificates without copying them
773 to all other hosts in the group.
775 <p>For the IFF scheme proceed as in the TC scheme to generate keys
776 and certificates for all group hosts, then for every trusted host in the group,
777 generate the IFF parameter file.
778 On trusted host alice run
779 <code>ntp-keygen</code>
782 <code>-p</code> <kbd>password</kbd>
783 to produce her parameter file
784 <span class="file">ntpkey_IFFpar_</span><kbd>alice.filestamp</kbd>,
785 which includes both server and client keys.
786 Copy this file to all group hosts that operate as both servers
787 and clients and install a soft link from the generic
788 <span class="file">ntpkey_iff_</span><kbd>alice</kbd>
790 If there are no hosts restricted to operate only as clients,
791 there is nothing further to do.
792 As the IFF scheme is independent
793 of keys and certificates, these files can be refreshed as needed.
795 <p>If a rogue client has the parameter file, it could masquerade
796 as a legitimate server and present a middleman threat.
797 To eliminate this threat, the client keys can be extracted
798 from the parameter file and distributed to all restricted clients.
799 After generating the parameter file, on alice run
800 <code>ntp-keygen</code>
802 and pipe the output to a file or mail program.
803 Copy or mail this file to all restricted clients.
804 On these clients install a soft link from the generic
805 <span class="file">ntpkey_iff_</span><kbd>alice</kbd>
807 To further protect the integrity of the keys,
808 each file can be encrypted with a secret password.
810 <p>For the GQ scheme proceed as in the TC scheme to generate keys
811 and certificates for all group hosts, then for every trusted host
812 in the group, generate the IFF parameter file.
813 On trusted host alice run
814 <code>ntp-keygen</code>
817 <code>-p</code> <kbd>password</kbd>
818 to produce her parameter file
819 <span class="file">ntpkey_GQpar_</span><kbd>alice.filestamp</kbd>,
820 which includes both server and client keys.
821 Copy this file to all group hosts and install a soft link
823 <span class="file">ntpkey_gq_</span><kbd>alice</kbd>
825 In addition, on each host bob install a soft link
827 <span class="file">ntpkey_gq_</span><kbd>bob</kbd>
829 As the GQ scheme updates the GQ parameters file and certificate
830 at the same time, keys and certificates can be regenerated as needed.
832 <p>For the MV scheme, proceed as in the TC scheme to generate keys
833 and certificates for all group hosts.
834 For illustration assume trish is the TA, alice one of several trusted hosts
835 and bob one of her clients.
837 <code>ntp-keygen</code>
838 <code>-V</code> <kbd>n</kbd>
839 <code>-p</code> <kbd>password</kbd>,
842 is the number of revokable keys (typically 5) to produce
844 <span class="file">ntpkeys_MVpar_</span><kbd>trish.filestamp</kbd>
846 <span class="file">ntpkeys_MVkeyd_</span><kbd>trish.filestamp</kbd>
849 is the key number (0 <
853 Copy the parameter file to alice and install a soft link
855 <span class="file">ntpkey_mv_</span><kbd>alice</kbd>
857 Copy one of the client key files to alice for later distribution
859 It doesn't matter which client key file goes to alice,
860 since they all work the same way.
861 Alice copies the client key file to all of her cliens.
862 On client bob install a soft link from generic
863 <span class="file">ntpkey_mvkey_</span><kbd>bob</kbd>
864 to the client key file.
865 As the MV scheme is independent of keys and certificates,
866 these files can be refreshed as needed.
868 <h5 class="subsubsection">Command Line Options</h5>
871 <dt><code>-c</code> <kbd>scheme</kbd><dd>Select certificate message digest/signature encryption scheme.
874 can be one of the following:
875 . Cm RSA-MD2 , RSA-MD5 , RSA-SHA , RSA-SHA1 , RSA-MDC2 , RSA-RIPEMD160 , DSA-SHA ,
877 <code>DSA-SHA1</code>.
878 Note that RSA schemes must be used with a RSA sign key and DSA
879 schemes must be used with a DSA sign key.
880 The default without this option is
881 <code>RSA-MD5</code>.
882 <br><dt><code>-d</code><dd>Enable debugging.
883 This option displays the cryptographic data produced in eye-friendly billboards.
884 <br><dt><code>-e</code><dd>Write the IFF client keys to the standard output.
885 This is intended for automatic key distribution by mail.
886 <br><dt><code>-G</code><dd>Generate parameters and keys for the GQ identification scheme,
887 obsoleting any that may exist.
888 <br><dt><code>-g</code><dd>Generate keys for the GQ identification scheme
889 using the existing GQ parameters.
890 If the GQ parameters do not yet exist, create them first.
891 <br><dt><code>-H</code><dd>Generate new host keys, obsoleting any that may exist.
892 <br><dt><code>-I</code><dd>Generate parameters for the IFF identification scheme,
893 obsoleting any that may exist.
894 <br><dt><code>-i</code> <kbd>name</kbd><dd>Set the suject name to
896 This is used as the subject field in certificates
897 and in the file name for host and sign keys.
898 <br><dt><code>-M</code><dd>Generate MD5 keys, obsoleting any that may exist.
899 <br><dt><code>-P</code><dd>Generate a private certificate.
900 By default, the program generates public certificates.
901 <br><dt><code>-p</code> <kbd>password</kbd><dd>Encrypt generated files containing private data with
903 and the DES-CBC algorithm.
904 <br><dt><code>-q</code><dd>Set the password for reading files to password.
905 <br><dt><code>-S</code> <code>[RSA | DSA]</code><dd>Generate a new sign key of the designated type,
906 obsoleting any that may exist.
907 By default, the program uses the host key as the sign key.
908 <br><dt><code>-s</code> <kbd>name</kbd><dd>Set the issuer name to
910 This is used for the issuer field in certificates
911 and in the file name for identity files.
912 <br><dt><code>-T</code><dd>Generate a trusted certificate.
913 By default, the program generates a non-trusted certificate.
914 <br><dt><code>-V</code> <kbd>nkeys</kbd><dd>Generate parameters and keys for the Mu-Varadharajan (MV) identification scheme.
917 <h5 class="subsubsection">Random Seed File</h5>
919 <p>All cryptographically sound key generation schemes must have means
920 to randomize the entropy seed used to initialize
921 the internal pseudo-random number generator used
922 by the library routines.
923 The OpenSSL library uses a designated random seed file for this purpose.
924 The file must be available when starting the NTP daemon and
925 <code>ntp-keygen</code>
927 If a site supports OpenSSL or its companion OpenSSH,
928 it is very likely that means to do this are already available.
930 <p>It is important to understand that entropy must be evolved
931 for each generation, for otherwise the random number sequence
932 would be predictable.
933 Various means dependent on external events, such as keystroke intervals,
934 can be used to do this and some systems have built-in entropy sources.
935 Suitable means are described in the OpenSSL software documentation,
936 but are outside the scope of this page.
938 <p>The entropy seed used by the OpenSSL library is contained in a file,
941 which must be available when starting the NTP daemon
943 <code>ntp-keygen</code>
945 The NTP daemon will first look for the file
946 using the path specified by the
947 <code>randfile</code>
950 configuration command.
951 If not specified in this way, or when starting the
952 <code>ntp-keygen</code>
954 the OpenSSL library will look for the file using the path specified
957 environment variable in the user home directory,
958 whether root or some other user.
961 environment variable is not present,
962 the library will look for the
964 file in the user home directory.
965 If the file is not available or cannot be written,
966 the daemon exits with a message to the system log and the program
967 exits with a suitable error message.
969 <h5 class="subsubsection">Cryptographic Data Files</h5>
971 <p>All other file formats begin with two lines.
972 The first contains the file name, including the generated host name
974 The second contains the datestamp in conventional Unix date format.
975 Lines beginning with # are considered comments and ignored by the
976 <code>ntp-keygen</code>
978 <code>ntpd(1ntpdmdoc)</code>
980 Cryptographic values are encoded first using ASN.1 rules,
981 then encrypted if necessary, and finally written PEM-encoded
982 printable ASCII format preceded and followed by MIME content identifier lines.
984 <p>The format of the symmetric keys file is somewhat different
985 than the other files in the interest of backward compatibility.
986 Since DES-CBC is deprecated in NTPv4, the only key format of interest
987 is MD5 alphanumeric strings.
988 Following hte heard the keys are
989 entered one per line in the format
990 <pre class="example"> <kbd>keyno</kbd> <kbd>type</kbd> <kbd>key</kbd>
994 is a positive integer in the range 1-65,535,
996 is the string MD5 defining the key format and
999 which is a printable ASCII string 16 characters or less in length.
1000 Each character is chosen from the 93 printable characters
1001 in the range 0x21 through 0x7f excluding space and the
1005 <p>Note that the keys used by the
1006 <code>ntpq(1ntpqmdoc)</code>
1008 <code>ntpdc(1ntpdcmdoc)</code>
1010 are checked against passwords requested by the programs
1011 and entered by hand, so it is generally appropriate to specify these keys
1012 in human readable ASCII format.
1015 <code>ntp-keygen</code>
1016 program generates a MD5 symmetric keys file
1017 <span class="file">ntpkey_MD5key_</span><kbd>hostname.filestamp</kbd>.
1018 Since the file contains private shared keys,
1019 it should be visible only to root and distributed by secure means
1020 to other subnet hosts.
1021 The NTP daemon loads the file
1022 <span class="file">ntp.keys</span>,
1024 <code>ntp-keygen</code>
1025 installs a soft link from this name to the generated file.
1026 Subsequently, similar soft links must be installed by manual
1027 or automated means on the other subnet hosts.
1028 While this file is not used with the Autokey Version 2 protocol,
1029 it is needed to authenticate some remote configuration commands
1031 <code>ntpq(1ntpqmdoc)</code>
1033 <code>ntpdc(1ntpdcmdoc)</code>
1036 <p>This section was generated by <strong>AutoGen</strong>,
1037 using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntp-keygen</code> program.
1038 This software is released under the NTP license, <http://ntp.org/license>.
1041 <li><a accesskey="1" href="#ntp_002dkeygen-usage">ntp-keygen usage</a>: ntp-keygen help/usage (<span class="option">--help</span>)
1042 <li><a accesskey="2" href="#ntp_002dkeygen-imbits">ntp-keygen imbits</a>: imbits option (-b)
1043 <li><a accesskey="3" href="#ntp_002dkeygen-certificate">ntp-keygen certificate</a>: certificate option (-c)
1044 <li><a accesskey="4" href="#ntp_002dkeygen-cipher">ntp-keygen cipher</a>: cipher option (-C)
1045 <li><a accesskey="5" href="#ntp_002dkeygen-id_002dkey">ntp-keygen id-key</a>: id-key option (-e)
1046 <li><a accesskey="6" href="#ntp_002dkeygen-gq_002dparams">ntp-keygen gq-params</a>: gq-params option (-G)
1047 <li><a accesskey="7" href="#ntp_002dkeygen-host_002dkey">ntp-keygen host-key</a>: host-key option (-H)
1048 <li><a accesskey="8" href="#ntp_002dkeygen-iffkey">ntp-keygen iffkey</a>: iffkey option (-I)
1049 <li><a accesskey="9" href="#ntp_002dkeygen-ident">ntp-keygen ident</a>: ident option (-i)
1050 <li><a href="#ntp_002dkeygen-lifetime">ntp-keygen lifetime</a>: lifetime option (-l)
1051 <li><a href="#ntp_002dkeygen-md5key">ntp-keygen md5key</a>: md5key option (-M)
1052 <li><a href="#ntp_002dkeygen-modulus">ntp-keygen modulus</a>: modulus option (-m)
1053 <li><a href="#ntp_002dkeygen-pvt_002dcert">ntp-keygen pvt-cert</a>: pvt-cert option (-P)
1054 <li><a href="#ntp_002dkeygen-password">ntp-keygen password</a>: password option (-p)
1055 <li><a href="#ntp_002dkeygen-export_002dpasswd">ntp-keygen export-passwd</a>: export-passwd option (-q)
1056 <li><a href="#ntp_002dkeygen-sign_002dkey">ntp-keygen sign-key</a>: sign-key option (-S)
1057 <li><a href="#ntp_002dkeygen-subject_002dname">ntp-keygen subject-name</a>: subject-name option (-s)
1058 <li><a href="#ntp_002dkeygen-trusted_002dcert">ntp-keygen trusted-cert</a>: trusted-cert option (-T)
1059 <li><a href="#ntp_002dkeygen-mv_002dparams">ntp-keygen mv-params</a>: mv-params option (-V)
1060 <li><a href="#ntp_002dkeygen-mv_002dkeys">ntp-keygen mv-keys</a>: mv-keys option (-v)
1061 <li><a href="#ntp_002dkeygen-config">ntp-keygen config</a>: presetting/configuring ntp-keygen
1062 <li><a href="#ntp_002dkeygen-exit-status">ntp-keygen exit status</a>: exit status
1063 <li><a href="#ntp_002dkeygen-Usage">ntp-keygen Usage</a>: Usage
1064 <li><a href="#ntp_002dkeygen-Notes">ntp-keygen Notes</a>: Notes
1065 <li><a href="#ntp_002dkeygen-Bugs">ntp-keygen Bugs</a>: Bugs
1070 <a name="ntp_002dkeygen-usage"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-imbits">ntp-keygen imbits</a>,
1071 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1075 <h4 class="subsection">ntp-keygen help/usage (<span class="option">--help</span>)</h4>
1077 <p><a name="index-ntp_002dkeygen-help-3"></a>
1078 This is the automatically generated usage text for ntp-keygen.
1080 <p>The text printed is the same whether selected with the <code>help</code> option
1081 (<span class="option">--help</span>) or the <code>more-help</code> option (<span class="option">--more-help</span>). <code>more-help</code> will print
1082 the usage text by passing it through a pager program.
1083 <code>more-help</code> is disabled on platforms without a working
1084 <code>fork(2)</code> function. The <code>PAGER</code> environment variable is
1085 used to select the program, defaulting to <span class="file">more</span>. Both will exit
1086 with a status code of 0.
1088 <pre class="example">ntp-keygen (ntp) - Create a NTP host key - Ver. 4.2.8p9-RC
1089 Usage: ntp-keygen [ -<flag> [<val>] | --<name>[{=| }<val>] ]...
1090 Flg Arg Option-Name Description
1091 -b Num imbits identity modulus bits
1092 - it must be in the range:
1094 -c Str certificate certificate scheme
1095 -C Str cipher privatekey cipher
1096 -d no debug-level Increase debug verbosity level
1097 - may appear multiple times
1098 -D Num set-debug-level Set the debug verbosity level
1099 - may appear multiple times
1100 -e no id-key Write IFF or GQ identity keys
1101 -G no gq-params Generate GQ parameters and keys
1102 -H no host-key generate RSA host key
1103 -I no iffkey generate IFF parameters
1104 -i Str ident set Autokey group name
1105 -l Num lifetime set certificate lifetime
1106 -M no md5key generate MD5 keys
1107 -m Num modulus modulus
1108 - it must be in the range:
1110 -P no pvt-cert generate PC private certificate
1111 -p Str password local private password
1112 -q Str export-passwd export IFF or GQ group keys with password
1113 -S Str sign-key generate sign key (RSA or DSA)
1114 -s Str subject-name set host and optionally group name
1115 -T no trusted-cert trusted certificate (TC scheme)
1116 -V Num mv-params generate <num> MV parameters
1117 -v Num mv-keys update <num> MV keys
1118 opt version output version information and exit
1119 -? no help display extended usage information and exit
1120 -! no more-help extended usage information passed thru pager
1121 -> opt save-opts save the option state to a config file
1122 -< Str load-opts load options from a config file
1123 - disabled as '--no-load-opts'
1124 - may appear multiple times
1126 Options are specified by doubled hyphens and their name or by a single
1127 hyphen and the flag character.
1130 The following option preset mechanisms are supported:
1131 - reading file $HOME/.ntprc
1132 - reading file ./.ntprc
1133 - examining environment variables named NTP_KEYGEN_*
1135 Please send bug reports to: <http://bugs.ntp.org, bugs@ntp.org>
1139 <a name="ntp_002dkeygen-imbits"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-certificate">ntp-keygen certificate</a>,
1140 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-usage">ntp-keygen usage</a>,
1141 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1145 <h4 class="subsection">imbits option (-b)</h4>
1147 <p><a name="index-ntp_002dkeygen_002dimbits-4"></a>
1148 This is the “identity modulus bits” option.
1149 This option takes a number argument <span class="file">imbits</span>.
1151 <p class="noindent">This option has some usage constraints. It:
1153 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1156 <p>The number of bits in the identity modulus. The default is 256.
1159 <a name="ntp_002dkeygen-certificate"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-cipher">ntp-keygen cipher</a>,
1160 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-imbits">ntp-keygen imbits</a>,
1161 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1165 <h4 class="subsection">certificate option (-c)</h4>
1167 <p><a name="index-ntp_002dkeygen_002dcertificate-5"></a>
1168 This is the “certificate scheme” option.
1169 This option takes a string argument <span class="file">scheme</span>.
1171 <p class="noindent">This option has some usage constraints. It:
1173 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1177 RSA-MD2, RSA-MD5, RSA-SHA, RSA-SHA1, RSA-MDC2, RSA-RIPEMD160,
1178 DSA-SHA, or DSA-SHA1.
1180 <p>Select the certificate message digest/signature encryption scheme.
1181 Note that RSA schemes must be used with a RSA sign key and DSA
1182 schemes must be used with a DSA sign key. The default without
1183 this option is RSA-MD5.
1186 <a name="ntp_002dkeygen-cipher"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-id_002dkey">ntp-keygen id-key</a>,
1187 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-certificate">ntp-keygen certificate</a>,
1188 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1192 <h4 class="subsection">cipher option (-C)</h4>
1194 <p><a name="index-ntp_002dkeygen_002dcipher-6"></a>
1195 This is the “privatekey cipher” option.
1196 This option takes a string argument <span class="file">cipher</span>.
1198 <p class="noindent">This option has some usage constraints. It:
1200 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1203 <p>Select the cipher which is used to encrypt the files containing
1204 private keys. The default is three-key triple DES in CBC mode,
1205 equivalent to "<code>-C des-ede3-cbc". The openssl tool lists ciphers
1206 available in "openssl -h" output.
1207 </code><div class="node">
1209 <a name="ntp_002dkeygen-id_002dkey"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-gq_002dparams">ntp-keygen gq-params</a>,
1210 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-cipher">ntp-keygen cipher</a>,
1211 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1215 <h4 class="subsection">id-key option (-e)</h4>
1217 <p><a name="index-ntp_002dkeygen_002did_002dkey-7"></a>
1218 This is the “write iff or gq identity keys” option.
1220 <p class="noindent">This option has some usage constraints. It:
1222 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1225 <p>Write the IFF or GQ client keys to the standard output. This is
1226 intended for automatic key distribution by mail.
1229 <a name="ntp_002dkeygen-gq_002dparams"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-host_002dkey">ntp-keygen host-key</a>,
1230 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-id_002dkey">ntp-keygen id-key</a>,
1231 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1235 <h4 class="subsection">gq-params option (-G)</h4>
1237 <p><a name="index-ntp_002dkeygen_002dgq_002dparams-8"></a>
1238 This is the “generate gq parameters and keys” option.
1240 <p class="noindent">This option has some usage constraints. It:
1242 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1245 <p>Generate parameters and keys for the GQ identification scheme,
1246 obsoleting any that may exist.
1249 <a name="ntp_002dkeygen-host_002dkey"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-iffkey">ntp-keygen iffkey</a>,
1250 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-gq_002dparams">ntp-keygen gq-params</a>,
1251 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1255 <h4 class="subsection">host-key option (-H)</h4>
1257 <p><a name="index-ntp_002dkeygen_002dhost_002dkey-9"></a>
1258 This is the “generate rsa host key” option.
1260 <p class="noindent">This option has some usage constraints. It:
1262 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1265 <p>Generate new host keys, obsoleting any that may exist.
1268 <a name="ntp_002dkeygen-iffkey"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-ident">ntp-keygen ident</a>,
1269 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-host_002dkey">ntp-keygen host-key</a>,
1270 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1274 <h4 class="subsection">iffkey option (-I)</h4>
1276 <p><a name="index-ntp_002dkeygen_002diffkey-10"></a>
1277 This is the “generate iff parameters” option.
1279 <p class="noindent">This option has some usage constraints. It:
1281 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1284 <p>Generate parameters for the IFF identification scheme, obsoleting
1288 <a name="ntp_002dkeygen-ident"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-lifetime">ntp-keygen lifetime</a>,
1289 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-iffkey">ntp-keygen iffkey</a>,
1290 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1294 <h4 class="subsection">ident option (-i)</h4>
1296 <p><a name="index-ntp_002dkeygen_002dident-11"></a>
1297 This is the “set autokey group name” option.
1298 This option takes a string argument <span class="file">group</span>.
1300 <p class="noindent">This option has some usage constraints. It:
1302 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1305 <p>Set the optional Autokey group name to name. This is used in
1306 the file name of IFF, GQ, and MV client parameters files. In
1307 that role, the default is the host name if this option is not
1308 provided. The group name, if specified using <code>-i/--ident</code> or
1309 using <code>-s/--subject-name</code> following an '<code>}' character,
1310 is also a part of the self-signed host certificate's subject and
1311 issuer names in the form host
1312 <p>'crypto ident' or 'server ident' configuration in
1313 ntpd's configuration file.
1314 </code><div class="node">
1316 <a name="ntp_002dkeygen-lifetime"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-md5key">ntp-keygen md5key</a>,
1317 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-ident">ntp-keygen ident</a>,
1318 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1322 <h4 class="subsection">lifetime option (-l)</h4>
1324 <p><a name="index-ntp_002dkeygen_002dlifetime-12"></a>
1325 This is the ``set certificate lifetime'' option.
1326 This option takes a number argument <span class="file">lifetime</span>.
1328 <p class="noindent">This option has some usage constraints. It:
1330 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1333 <p>Set the certificate expiration to lifetime days from now.
1336 <a name="ntp_002dkeygen-md5key"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-modulus">ntp-keygen modulus</a>,
1337 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-lifetime">ntp-keygen lifetime</a>,
1338 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1342 <h4 class="subsection">md5key option (-M)</h4>
1344 <p><a name="index-ntp_002dkeygen_002dmd5key-13"></a>
1345 This is the ``generate md5 keys'' option.
1346 Generate MD5 keys, obsoleting any that may exist.
1349 <a name="ntp_002dkeygen-modulus"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-pvt_002dcert">ntp-keygen pvt-cert</a>,
1350 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-md5key">ntp-keygen md5key</a>,
1351 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1355 <h4 class="subsection">modulus option (-m)</h4>
1357 <p><a name="index-ntp_002dkeygen_002dmodulus-14"></a>
1358 This is the ``modulus'' option.
1359 This option takes a number argument <span class="file">modulus</span>.
1361 <p class="noindent">This option has some usage constraints. It:
1363 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1366 <p>The number of bits in the prime modulus. The default is 512.
1369 <a name="ntp_002dkeygen-pvt_002dcert"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-password">ntp-keygen password</a>,
1370 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-modulus">ntp-keygen modulus</a>,
1371 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1375 <h4 class="subsection">pvt-cert option (-P)</h4>
1377 <p><a name="index-ntp_002dkeygen_002dpvt_002dcert-15"></a>
1378 This is the ``generate pc private certificate'' option.
1380 <p class="noindent">This option has some usage constraints. It:
1382 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1385 <p>Generate a private certificate. By default, the program generates
1386 public certificates.
1389 <a name="ntp_002dkeygen-password"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-export_002dpasswd">ntp-keygen export-passwd</a>,
1390 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-pvt_002dcert">ntp-keygen pvt-cert</a>,
1391 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1395 <h4 class="subsection">password option (-p)</h4>
1397 <p><a name="index-ntp_002dkeygen_002dpassword-16"></a>
1398 This is the ``local private password'' option.
1399 This option takes a string argument <span class="file">passwd</span>.
1401 <p class="noindent">This option has some usage constraints. It:
1403 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1406 <p>Local files containing private data are encrypted with the
1407 DES-CBC algorithm and the specified password. The same password
1408 must be specified to the local ntpd via the "crypto pw password"
1409 configuration command. The default password is the local
1413 <a name="ntp_002dkeygen-export_002dpasswd"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-sign_002dkey">ntp-keygen sign-key</a>,
1414 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-password">ntp-keygen password</a>,
1415 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1419 <h4 class="subsection">export-passwd option (-q)</h4>
1421 <p><a name="index-ntp_002dkeygen_002dexport_002dpasswd-17"></a>
1422 This is the ``export iff or gq group keys with password'' option.
1423 This option takes a string argument <span class="file">passwd</span>.
1425 <p class="noindent">This option has some usage constraints. It:
1427 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1430 <p>Export IFF or GQ identity group keys to the standard output,
1431 encrypted with the DES-CBC algorithm and the specified password.
1432 The same password must be specified to the remote ntpd via the
1433 "crypto pw password" configuration command. See also the option
1434 --id-key (-e) for unencrypted exports.
1437 <a name="ntp_002dkeygen-sign_002dkey"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-subject_002dname">ntp-keygen subject-name</a>,
1438 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-export_002dpasswd">ntp-keygen export-passwd</a>,
1439 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1443 <h4 class="subsection">sign-key option (-S)</h4>
1445 <p><a name="index-ntp_002dkeygen_002dsign_002dkey-18"></a>
1446 This is the ``generate sign key (rsa or dsa)'' option.
1447 This option takes a string argument <span class="file">sign</span>.
1449 <p class="noindent">This option has some usage constraints. It:
1451 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1454 <p>Generate a new sign key of the designated type, obsoleting any
1455 that may exist. By default, the program uses the host key as the
1459 <a name="ntp_002dkeygen-subject_002dname"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-trusted_002dcert">ntp-keygen trusted-cert</a>,
1460 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-sign_002dkey">ntp-keygen sign-key</a>,
1461 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1465 <h4 class="subsection">subject-name option (-s)</h4>
1467 <p><a name="index-ntp_002dkeygen_002dsubject_002dname-19"></a>
1468 This is the ``set host and optionally group name'' option.
1469 This option takes a string argument <span class="file">host@group</span>.
1471 <p class="noindent">This option has some usage constraints. It:
1473 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1476 <p>Set the Autokey host name, and optionally, group name specified
1477 following an '<code>}' character. The host name is used in the file
1478 name of generated host and signing certificates, without the
1479 group name. The host name, and if provided, group name are used
1481 <p>fields. Specifying '-s
1482 <p>leaving the host name unchanged while appending
1483 <p>subject and issuer fields, as with -i group. The group name, or
1484 if not provided, the host name are also used in the file names
1485 of IFF, GQ, and MV client parameter files.
1486 </code><div class="node">
1488 <a name="ntp_002dkeygen-trusted_002dcert"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-mv_002dparams">ntp-keygen mv-params</a>,
1489 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-subject_002dname">ntp-keygen subject-name</a>,
1490 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1494 <h4 class="subsection">trusted-cert option (-T)</h4>
1496 <p><a name="index-ntp_002dkeygen_002dtrusted_002dcert-20"></a>
1497 This is the ``trusted certificate (tc scheme)'' option.
1499 <p class="noindent">This option has some usage constraints. It:
1501 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1504 <p>Generate a trusted certificate. By default, the program generates
1505 a non-trusted certificate.
1508 <a name="ntp_002dkeygen-mv_002dparams"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-mv_002dkeys">ntp-keygen mv-keys</a>,
1509 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-trusted_002dcert">ntp-keygen trusted-cert</a>,
1510 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1514 <h4 class="subsection">mv-params option (-V)</h4>
1516 <p><a name="index-ntp_002dkeygen_002dmv_002dparams-21"></a>
1517 This is the ``generate <num> mv parameters'' option.
1518 This option takes a number argument <span class="file">num</span>.
1520 <p class="noindent">This option has some usage constraints. It:
1522 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1525 <p>Generate parameters and keys for the Mu-Varadharajan (MV)
1526 identification scheme.
1529 <a name="ntp_002dkeygen-mv_002dkeys"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-config">ntp-keygen config</a>,
1530 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-mv_002dparams">ntp-keygen mv-params</a>,
1531 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1535 <h4 class="subsection">mv-keys option (-v)</h4>
1537 <p><a name="index-ntp_002dkeygen_002dmv_002dkeys-22"></a>
1538 This is the ``update <num> mv keys'' option.
1539 This option takes a number argument <span class="file">num</span>.
1541 <p class="noindent">This option has some usage constraints. It:
1543 <li>must be compiled in by defining <code>AUTOKEY</code> during the compilation.
1546 <p>This option has no <span class="samp">doc</span> documentation.
1550 <a name="ntp_002dkeygen-config"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-exit-status">ntp-keygen exit status</a>,
1551 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-mv_002dkeys">ntp-keygen mv-keys</a>,
1552 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1556 <h4 class="subsection">presetting/configuring ntp-keygen</h4>
1558 <p>Any option that is not marked as <i>not presettable</i> may be preset by
1559 loading values from configuration ("rc" or "ini") files, and values from environment variables named <code>NTP-KEYGEN</code> and <code>NTP-KEYGEN_<OPTION_NAME></code>. <code><OPTION_NAME></code> must be one of
1560 the options listed above in upper case and segmented with underscores.
1561 The <code>NTP-KEYGEN</code> variable will be tokenized and parsed like
1562 the command line. The remaining variables are tested for existence and their
1563 values are treated like option arguments.
1565 <p class="noindent"><code>libopts</code> will search in 2 places for configuration files:
1570 The environment variables <code>HOME</code>, and <code>PWD</code>
1571 are expanded and replaced when <span class="file">ntp-keygen</span> runs.
1572 For any of these that are plain files, they are simply processed.
1573 For any that are directories, then a file named <span class="file">.ntprc</span> is searched for
1574 within that directory and processed.
1576 <p>Configuration files may be in a wide variety of formats.
1577 The basic format is an option name followed by a value (argument) on the
1578 same line. Values may be separated from the option name with a colon,
1579 equal sign or simply white space. Values may be continued across multiple
1580 lines by escaping the newline with a backslash.
1582 <p>Multiple programs may also share the same initialization file.
1583 Common options are collected at the top, followed by program specific
1584 segments. The segments are separated by lines like:
1585 <pre class="example"> [NTP-KEYGEN]
1587 <p class="noindent">or by
1588 <pre class="example"> <?program ntp-keygen>
1590 <p class="noindent">Do not mix these styles within one configuration file.
1592 <p>Compound values and carefully constructed string values may also be
1593 specified using XML syntax:
1594 <pre class="example"> <option-name>
1595 <sub-opt>...&lt;...&gt;...</sub-opt>
1596 </option-name>
1598 <p class="noindent">yielding an <code>option-name.sub-opt</code> string value of
1599 <pre class="example"> "...<...>..."
1601 <p><code>AutoOpts</code> does not track suboptions. You simply note that it is a
1602 hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching
1603 the associated name/value pair list (see: optionFindValue).
1605 <p>The command line options relating to configuration and/or usage help are:
1607 <h5 class="subsubheading">version (-)</h5>
1609 <p>Print the program version to standard out, optionally with licensing
1610 information, then exit 0. The optional argument specifies how much licensing
1611 detail to provide. The default is to print just the version. The licensing infomation may be selected with an option argument.
1612 Only the first letter of the argument is examined:
1615 <dt><span class="samp">version</span><dd>Only print the version. This is the default.
1616 <br><dt><span class="samp">copyright</span><dd>Name the copyright usage licensing terms.
1617 <br><dt><span class="samp">verbose</span><dd>Print the full copyright usage licensing terms.
1622 <a name="ntp_002dkeygen-exit-status"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-Usage">ntp-keygen Usage</a>,
1623 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-config">ntp-keygen config</a>,
1624 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1628 <h4 class="subsection">ntp-keygen exit status</h4>
1630 <p>One of the following exit values will be returned:
1632 <dt><span class="samp">0 (EXIT_SUCCESS)</span><dd>Successful program execution.
1633 <br><dt><span class="samp">1 (EXIT_FAILURE)</span><dd>The operation failed or the command syntax was not valid.
1634 <br><dt><span class="samp">66 (EX_NOINPUT)</span><dd>A specified configuration file could not be loaded.
1635 <br><dt><span class="samp">70 (EX_SOFTWARE)</span><dd>libopts had an internal operational error. Please report
1636 it to autogen-users@lists.sourceforge.net. Thank you.
1640 <a name="ntp_002dkeygen-Usage"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-Notes">ntp-keygen Notes</a>,
1641 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-exit-status">ntp-keygen exit status</a>,
1642 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1646 <h4 class="subsection">ntp-keygen Usage</h4>
1650 <a name="ntp_002dkeygen-Notes"></a>Next: <a rel="next" accesskey="n" href="#ntp_002dkeygen-Bugs">ntp-keygen Bugs</a>,
1651 Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-Usage">ntp-keygen Usage</a>,
1652 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1656 <h4 class="subsection">ntp-keygen Notes</h4>
1660 <a name="ntp_002dkeygen-Bugs"></a>Previous: <a rel="previous" accesskey="p" href="#ntp_002dkeygen-Notes">ntp-keygen Notes</a>,
1661 Up: <a rel="up" accesskey="u" href="#ntp_002dkeygen-Invocation">ntp-keygen Invocation</a>
1665 <h4 class="subsection">ntp-keygen Bugs</h4>
1669 <a name="Random-Seed-File"></a>Next: <a rel="next" accesskey="n" href="#Cryptographic-Data-Files">Cryptographic Data Files</a>,
1670 Previous: <a rel="previous" accesskey="p" href="#Running-the-Program">Running the Program</a>,
1671 Up: <a rel="up" accesskey="u" href="#Top">Top</a>
1675 <!-- node-name, next, previous, up -->
1676 <h3 class="section">Random Seed File</h3>
1678 <p>All cryptographically sound key generation schemes must have means to
1679 randomize the entropy seed used to initialize the internal
1680 pseudo-random number generator used by the OpenSSL library routines.
1681 If a site supports ssh, it is very likely that means to do this are
1683 The entropy seed used by the OpenSSL library is contained in a file,
1684 usually called <code>.rnd</code>, which must be available when
1685 starting the <code>ntp-keygen</code> program or <code>ntpd</code> daemon.
1687 <p>The OpenSSL library looks for the file using the path specified by the
1688 <code>RANDFILE</code> environment variable in the user home directory, whether root
1690 If the <code>RANDFILE</code> environment variable is not
1691 present, the library looks for the <code>.rnd</code> file in the user home
1693 Since both the <code>ntp-keygen</code> program and <code>ntpd</code> daemon must run
1694 as root, the logical place to put this file is in <code>/.rnd</code> or
1695 <code>/root/.rnd</code>.
1696 If the file is not available or cannot be written, the program exits
1697 with a message to the system log.
1701 <a name="Cryptographic-Data-Files"></a>Previous: <a rel="previous" accesskey="p" href="#Random-Seed-File">Random Seed File</a>,
1702 Up: <a rel="up" accesskey="u" href="#Top">Top</a>
1706 <!-- node-name, next, previous, up -->
1707 <h3 class="section">Cryptographic Data Files</h3>
1709 <p>File and link names are in the <code>form ntpkey_key_name.fstamp</code>,
1710 where <code>key</code> is the key or parameter type,
1711 <code>name</code> is the host or group name and
1712 <code>fstamp</code> is the filestamp (NTP seconds) when the file was created).
1713 By convention, key names in generated file names include both upper and
1714 lower case characters, while key names in generated link names include
1715 only lower case characters. The filestamp is not used in generated link
1718 <p>The key name is a string defining the cryptographic key type.
1719 Key types include public/private keys host and sign, certificate cert
1720 and several challenge/response key types.
1721 By convention, client files used for
1722 challenges have a par subtype, as in the IFF challenge IFFpar, while
1723 server files for responses have a key subtype, as in the GQ response
1726 <p>All files begin with two nonencrypted lines. The first line contains
1727 the file name in the format <code>ntpkey_key_host.fstamp</code>.
1728 The second line contains the datestamp in conventional Unix date format.
1729 Lines beginning with <code>#</code> are ignored.
1731 <p>The remainder of the file contains cryptographic data encoded first
1732 using ASN.1 rules, then encrypted using the DES-CBC algorithm with
1733 given password and finally written in PEM-encoded printable ASCII text
1734 preceded and followed by MIME content identifier lines.
1736 <p>The format of the symmetric keys file, ordinarily named <code>ntp.keys</code>,
1737 is somewhat different than the other files in the interest of backward
1739 Ordinarily, the file is generated by this program, but
1740 it can be constructed and edited using an ordinary text editor.
1742 <pre class="example"> # ntpkey_MD5key_hms.local.3564038757
1743 # Sun Dec 9 02:45:57 2012
1745 1 MD5 "]!ghT%O;3)WJ,/Nc:>I # MD5 key
1746 2 MD5 lu+H^tF46BKR-6~pV_5 # MD5 key
1747 3 MD5 :lnoVsE%Yz*avh%EtNC # MD5 key
1748 4 MD5 |fdZrf0sF~^V # MD5 key
1749 5 MD5 IyAG>O"y"LmCRS!*bHC # MD5 key
1750 6 MD5 ">e\A # MD5 key
1751 7 MD5 c9x=M'CfLxax9v)PV-si # MD5 key
1752 8 MD5 E|=jvFVov?Bn|Ev=&aK\ # MD5 key
1753 9 MD5 T!c4UT&`(m$+m+B6,`Q0 # MD5 key
1754 10 MD5 JVF/1=)=IFbHbJQz..Cd # MD5 key
1755 11 SHA1 6dea311109529e436c2b4fccae9bc753c16d1b48 # SHA1 key
1756 12 SHA1 7076f373d86c4848c59ff8046e49cb7d614ec394 # SHA1 key
1757 13 SHA1 5f48b1b60591eb01b7cf1d33b7774f08d20262d3 # SHA1 key
1758 14 SHA1 eed5ab9d9497319ec60cf3781d52607e76720178 # SHA1 key
1759 15 SHA1 f283562611a04c964da8126296f5f8e58c3f85de # SHA1 key
1760 16 SHA1 1930da171297dd63549af50b29449de17dcf341f # SHA1 key
1761 17 SHA1 fee892110358cd4382322b889869e750db8e8a8f # SHA1 key
1762 18 SHA1 b5520c9fadd7ad3fd8bfa061c8821b65d029bb37 # SHA1 key
1763 19 SHA1 8c74fb440ec80f453ec6aaa62b9baed0ab723b92 # SHA1 key
1764 20 SHA1 6bc05f734306a189326000970c19b3910f403795 # SHA1 key
1766 <p>Figure 1. Typical Symmetric Key File
1768 <p>Figure 1 shows a typical symmetric keys file used by the reference
1770 Each line of the file contains three fields, first an
1771 integer between 1 and 65534, inclusive, representing the key identifier
1772 used in the server and peer configuration commands.
1773 Next is the key type for the message digest algorithm,
1774 which in the absence of the
1775 OpenSSL library must be MD5 to designate the MD5 message digest
1777 If the OpenSSL library is installed, the key type can be any
1778 message digest algorithm supported by that library.
1780 compatibility with FIPS 140-2 is required, the key type must be either
1782 The key type can be changed using an ASCII text editor.
1784 <p>An MD5 key consists of a printable ASCII string less than or equal to
1785 16 characters and terminated by whitespace or a # character.
1787 key consists of a hex-encoded ASCII string of 40 characters, which is
1788 truncated as necessary.
1790 <p>Note that the keys used by the <code>ntpq</code> and <code>ntpdc</code> programs are
1791 checked against passwords requested by the programs and entered by hand,
1793 is generally appropriate to specify these keys in human readable ASCII
1796 <p>The <code>ntp-keygen</code> program generates a MD5 symmetric keys file
1797 <code>ntpkey_MD5key_hostname.filestamp</code>.
1798 Since the file contains private
1799 shared keys, it should be visible only to root and distributed by
1800 secure means to other subnet hosts.
1801 The NTP daemon loads the file <code>ntp.keys</code>, so <code>ntp-keygen</code>
1802 installs a soft link from this name to the generated file.
1803 Subsequently, similar soft links must be installed by
1804 manual or automated means on the other subnet hosts.
1806 not used with the Autokey Version 2 protocol, it is needed to
1807 authenticate some remote configuration commands used by the <code>ntpq</code> and
1808 <code>ntpdc</code> utilities.