1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Created by GNU Texinfo 6.6, http://www.gnu.org/software/texinfo/ --> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 6<title>Ntp-keygen User’s Manual</title> 7 8<meta name="description" content="Ntp-keygen User’s Manual"> 9<meta name="keywords" content="Ntp-keygen User’s Manual"> 10<meta name="resource-type" content="document"> 11<meta name="distribution" content="global"> 12<meta name="Generator" content="makeinfo"> 13<link href="#Top" rel="start" title="Top"> 14<link href="dir.html#Top" rel="up" title="(dir)"> 15<style type="text/css"> 16<!-- 17a.summary-letter {text-decoration: none} 18blockquote.indentedblock {margin-right: 0em} 19div.display {margin-left: 3.2em} 20div.example {margin-left: 3.2em} 21div.lisp {margin-left: 3.2em} 22kbd {font-style: oblique} 23pre.display {font-family: inherit} 24pre.format {font-family: inherit} 25pre.menu-comment {font-family: serif} 26pre.menu-preformatted {font-family: serif} 27span.nolinebreak {white-space: nowrap} 28span.roman {font-family: initial; font-weight: normal} 29span.sansserif {font-family: sans-serif; font-weight: normal} 30ul.no-bullet {list-style: none} 31--> 32</style> 33 34 35</head> 36 37<body lang="en"> 38<h1 class="settitle" align="center">Ntp-keygen User’s Manual</h1> 39 40 41 42 43 44<span id="SEC_Overview"></span> 45<h2 class="shortcontents-heading">Short Table of Contents</h2> 46 47<div class="shortcontents"> 48<ul class="no-bullet"> 49<li><a id="stoc-Description-1" href="#toc-Description-1">1 Description</a></li> 50</ul> 51</div> 52 53 54<table class="menu" border="0" cellspacing="0"> 55<tr><td align="left" valign="top">• <a href="#Description" accesskey="1">Description</a></td><td> </td><td align="left" valign="top"> 56</td></tr> 57<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Invocation" accesskey="2">ntp-keygen Invocation</a></td><td> </td><td align="left" valign="top">Invoking ntp-keygen 58</td></tr> 59<tr><td align="left" valign="top">• <a href="#Running-the-Program" accesskey="3">Running the Program</a></td><td> </td><td align="left" valign="top"> 60</td></tr> 61<tr><td align="left" valign="top">• <a href="#Random-Seed-File" accesskey="4">Random Seed File</a></td><td> </td><td align="left" valign="top"> 62</td></tr> 63<tr><td align="left" valign="top">• <a href="#Cryptographic-Data-Files" accesskey="5">Cryptographic Data Files</a></td><td> </td><td align="left" valign="top"> 64</td></tr> 65</table> 66 67<span id="Top"></span><div class="header"> 68<p> 69Next: <a href="#Description" accesskey="n" rel="next">Description</a>, Previous: <a href="dir.html#Top" accesskey="p" rel="prev">(dir)</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> </p> 70</div> 71<span id="NTP-Key-Generation-Program-User-Manual"></span><h1 class="top">NTP Key Generation Program User Manual</h1> 72 73<p>This document describes the use of the NTP Project’s <code>ntp-keygen</code> 74program, that generates cryptographic data files used by the NTPv4 75authentication and identity schemes. 76It can generate message digest keys used in symmetric key cryptography and, 77if the OpenSSL software 78library has been installed, it can generate host keys, sign keys, 79certificates, and identity keys and parameters used by the Autokey 80public key cryptography. 81The message digest keys file is generated in a 82format compatible with NTPv3. 83All other files are in PEM-encoded 84printable ASCII format so they can be embedded as MIME attachments in 85mail to other sites. 86</p> 87<p>This document applies to version 4.2.8p17 of <code>ntp-keygen</code>. 88</p> 89<table class="menu" border="0" cellspacing="0"> 90<tr><td align="left" valign="top">• <a href="#Description" accesskey="1">Description</a></td><td> </td><td align="left" valign="top"> 91</td></tr> 92</table> 93 94<hr> 95<span id="Description"></span><div class="header"> 96<p> 97Next: <a href="#Running-the-Program" accesskey="n" rel="next">Running the Program</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p> 98</div> 99<span id="Description-1"></span><h2 class="chapter">1 Description</h2> 100 101<p>This program generates cryptographic data files used by the NTPv4 102authentication and identity schemes. It can generate message digest 103keys used in symmetric key cryptography and, if the OpenSSL software 104library has been installed, it can generate host keys, sign keys, 105certificates, and identity keys and parameters used by the Autokey 106public key cryptography. The message digest keys file is generated in a 107format compatible with NTPv3. All other files are in PEM-encoded 108printable ASCII format so they can be embedded as MIME attachments in 109mail to other sites. 110</p> 111<p>When used to generate message digest keys, the program produces a file 112containing ten pseudo-random printable ASCII strings suitable for the 113MD5 message digest algorithm included in the distribution. 114If the 115OpenSSL library is installed, it produces an additional ten hex-encoded 116random bit strings suitable for the SHA1 and other message digest 117algorithms. 118The message digest keys file must be distributed and stored 119using secure means beyond the scope of NTP itself. 120Besides the keys 121used for ordinary NTP associations, additional keys can be defined as 122passwords for the ntpq and ntpdc utility programs. 123</p> 124<p>The remaining generated files are compatible with other OpenSSL 125applications and other Public Key Infrastructure (PKI) resources. 126Certificates generated by this program are compatible with extant 127industry practice, although some users might find the interpretation of 128X509v3 extension fields somewhat liberal. 129However, the identity keys 130are probably not compatible with anything other than Autokey. 131</p> 132<p>Some files used by this program are encrypted using a private password. 133The <code>-p</code> option specifies the password for local encrypted files and the 134<code>-q</code> option the password for encrypted files sent to remote sites. 135If no password is specified, the host name returned by the Unix 136<code>gethostname()</code> function, normally the DNS name of the host, is used. 137</p> 138<p>The <kbd>pw</kbd> option of the <code>crypto</code> configuration command 139specifies the read password for previously encrypted local files. 140This must match the local password used by this program. 141If not specified, the host name is used. 142Thus, if files are generated by this program without password, 143they can be read back by ntpd without password, but only on the same 144host. 145</p> 146<p>Normally, encrypted files for each host are generated by that host and 147used only by that host, although exceptions exist as noted later on 148this page. 149The symmetric keys file, normally called <code>ntp.keys</code>, is 150usually installed in <code>/etc</code>. 151Other files and links are usually installed 152in <code>/usr/local/etc</code>, which is normally in a shared filesystem in 153NFS-mounted networks and cannot be changed by shared clients. 154The location of the keys directory can be changed by the keysdir 155configuration command in such cases. 156Normally, this is in <code>/etc</code>. 157</p> 158<p>This program directs commentary and error messages to the standard 159error stream <code>stderr</code> and remote files to the standard output stream 160<code>stdout</code> where they can be piped to other applications or redirected to 161files. 162The names used for generated files and links all begin with the 163string <code>ntpkey</code> and include the file type, 164generating host and filestamp, 165as described in the <a href="#Cryptographic-Data-Files">Cryptographic Data Files</a> section below. 166</p> 167<table class="menu" border="0" cellspacing="0"> 168<tr><td align="left" valign="top">• <a href="#Running-the-Program" accesskey="1">Running the Program</a></td><td> </td><td align="left" valign="top"> 169</td></tr> 170<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Invocation" accesskey="2">Invoking ntp-keygen</a></td><td> </td><td align="left" valign="top"> 171</td></tr> 172<tr><td align="left" valign="top">• <a href="#Random-Seed-File" accesskey="3">Random Seed File</a></td><td> </td><td align="left" valign="top"> 173</td></tr> 174<tr><td align="left" valign="top">• <a href="#Cryptographic-Data-Files" accesskey="4">Cryptographic Data Files</a></td><td> </td><td align="left" valign="top"> 175</td></tr> 176</table> 177 178<hr> 179<span id="Running-the-Program"></span><div class="header"> 180<p> 181Next: <a href="#Random-Seed-File" accesskey="n" rel="next">Random Seed File</a>, Previous: <a href="#Description" accesskey="p" rel="prev">Description</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p> 182</div> 183<span id="Running-the-Program-1"></span><h3 class="section">1.1 Running the Program</h3> 184 185<p>To test and gain experience with Autokey concepts, log in as root and 186change to the keys directory, usually <code>/usr/local/etc</code>. 187When run for the 188first time, or if all files with names beginning <code>ntpkey</code>] have been 189removed, use the <code>ntp-keygen</code> command without arguments to generate a 190default RSA host key and matching RSA-MD5 certificate with expiration 191date one year hence. 192If run again without options, the program uses the 193existing keys and parameters and generates only a new certificate with 194new expiration date one year hence. 195</p> 196<p>Run the command on as many hosts as necessary. 197Designate one of them as the trusted host (TH) using <code>ntp-keygen</code> 198with the <code>-T</code> option and configure 199it to synchronize from reliable Internet servers. 200Then configure the other hosts to synchronize to the TH directly or indirectly. 201A certificate trail is created when Autokey asks the immediately 202ascendant host towards the TH to sign its certificate, which is then 203provided to the immediately descendant host on request. 204All group hosts should have acyclic certificate trails ending on the TH. 205</p> 206<p>The host key is used to encrypt the cookie when required and so must be 207RSA type. 208By default, the host key is also the sign key used to encrypt signatures. 209A different sign key can be assigned using the <code>-S</code> option 210and this can be either RSA or DSA type. 211By default, the signature 212message digest type is MD5, but any combination of sign key type and 213message digest type supported by the OpenSSL library can be specified 214using the <code>-c</code> option. 215</p> 216<p>The rules say cryptographic media should be generated with proventic 217filestamps, which means the host should already be synchronized before 218this program is run. 219This of course creates a chicken-and-egg problem 220when the host is started for the first time. 221Accordingly, the host time 222should be set by some other means, such as eyeball-and-wristwatch, at 223least so that the certificate lifetime is within the current year. 224After that and when the host is synchronized to a proventic source, the 225certificate should be re-generated. 226</p> 227<p>Additional information on trusted groups and identity schemes is on the 228Autokey Public-Key Authentication page. 229</p> 230<hr> 231<span id="ntp_002dkeygen-Invocation"></span><div class="header"> 232<p> 233Next: <a href="#Random-Seed-File" accesskey="n" rel="next">Random Seed File</a>, Previous: <a href="#Running-the-Program" accesskey="p" rel="prev">Running the Program</a>, Up: <a href="#Description" accesskey="u" rel="up">Description</a> </p> 234</div> 235<span id="Invoking-ntp_002dkeygen"></span><h3 class="section">1.2 Invoking ntp-keygen</h3> 236<span id="index-ntp_002dkeygen"></span> 237<span id="index-Create-a-NTP-host-key"></span> 238 239 240 241<p>This program generates cryptographic data files used by the NTPv4 242authentication and identification schemes. 243It can generate message digest keys used in symmetric key cryptography and, 244if the OpenSSL software library has been installed, it can generate host keys, 245signing keys, certificates, and identity keys and parameters used in Autokey 246public key cryptography. 247These files are used for cookie encryption, 248digital signature, and challenge/response identification algorithms 249compatible with the Internet standard security infrastructure. 250</p> 251<p>The message digest symmetric keys file is generated in a format 252compatible with NTPv3. 253All other files are in PEM-encoded printable ASCII format, 254so they can be embedded as MIME attachments in email to other sites 255and certificate authorities. 256By default, files are not encrypted. 257</p> 258<p>When used to generate message digest symmetric keys, the program 259produces a file containing ten pseudo-random printable ASCII strings 260suitable for the MD5 message digest algorithm included in the 261distribution. 262If the OpenSSL library is installed, it produces an additional ten 263hex-encoded random bit strings suitable for SHA1, AES-128-CMAC, and 264other message digest algorithms. 265The message digest symmetric keys file must be distributed and stored 266using secure means beyond the scope of NTP itself. 267Besides the keys used for ordinary NTP associations, additional keys 268can be defined as passwords for the 269<code>ntpq(1ntpqmdoc)</code> 270and 271<code>ntpdc(1ntpdcmdoc)</code> 272utility programs. 273</p> 274<p>The remaining generated files are compatible with other OpenSSL 275applications and other Public Key Infrastructure (PKI) resources. 276Certificates generated by this program are compatible with extant 277industry practice, although some users might find the interpretation of 278X509v3 extension fields somewhat liberal. 279However, the identity keys are probably not compatible with anything 280other than Autokey. 281</p> 282<p>Some files used by this program are encrypted using a private password. 283The 284<code>-p</code> 285option specifies the read password for local encrypted files and the 286<code>-q</code> 287option the write password for encrypted files sent to remote sites. 288If no password is specified, the host name returned by the Unix 289<code>hostname(1)</code> 290command, normally the DNS name of the host, is used as the the default read 291password, for convenience. 292The 293<code>ntp-keygen</code> 294program prompts for the password if it reads an encrypted file 295and the password is missing or incorrect. 296If an encrypted file is read successfully and 297no write password is specified, the read password is used 298as the write password by default. 299</p> 300<p>The 301<code>pw</code> 302option of the 303<code>crypto</code> 304<code>ntpd(1ntpdmdoc)</code> 305configuration command specifies the read 306password for previously encrypted local files. 307This must match the local read password used by this program. 308If not specified, the host name is used. 309Thus, if files are generated by this program without an explicit password, 310they can be read back by 311<code>ntpd(1ntpdmdoc)</code> 312without specifying an explicit password but only on the same host. 313If the write password used for encryption is specified as the host name, 314these files can be read by that host with no explicit password. 315</p> 316<p>Normally, encrypted files for each host are generated by that host and 317used only by that host, although exceptions exist as noted later on 318this page. 319The symmetric keys file, normally called 320<samp>ntp.keys</samp>, 321is usually installed in 322<samp>/etc</samp>. 323Other files and links are usually installed in 324<samp>/usr/local/etc</samp>, 325which is normally in a shared filesystem in 326NFS-mounted networks and cannot be changed by shared clients. 327In these cases, NFS clients can specify the files in another 328directory such as 329<samp>/etc</samp> 330using the 331<code>keysdir</code> 332<code>ntpd(1ntpdmdoc)</code> 333configuration file command. 334</p> 335<p>This program directs commentary and error messages to the standard 336error stream 337<samp>stderr</samp> 338and remote files to the standard output stream 339<samp>stdout</samp> 340where they can be piped to other applications or redirected to files. 341The names used for generated files and links all begin with the 342string 343<samp>ntpkey*</samp> 344and include the file type, generating host and filestamp, 345as described in the 346<a href="#Cryptographic-Data-Files">Cryptographic Data Files</a> 347section below. 348</p> 349<table class="menu" border="0" cellspacing="0"> 350<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-usage" accesskey="1">ntp-keygen help/usage (<samp>--help</samp>)</a></td><td> </td><td align="left" valign="top"> 351</td></tr> 352<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-imbits" accesskey="2">imbits option (-b)</a></td><td> </td><td align="left" valign="top"> 353</td></tr> 354<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-certificate" accesskey="3">certificate option (-c)</a></td><td> </td><td align="left" valign="top"> 355</td></tr> 356<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-cipher" accesskey="4">cipher option (-C)</a></td><td> </td><td align="left" valign="top"> 357</td></tr> 358<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-id_002dkey" accesskey="5">id-key option (-e)</a></td><td> </td><td align="left" valign="top"> 359</td></tr> 360<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-gq_002dparams" accesskey="6">gq-params option (-G)</a></td><td> </td><td align="left" valign="top"> 361</td></tr> 362<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-host_002dkey" accesskey="7">host-key option (-H)</a></td><td> </td><td align="left" valign="top"> 363</td></tr> 364<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-iffkey" accesskey="8">iffkey option (-I)</a></td><td> </td><td align="left" valign="top"> 365</td></tr> 366<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-ident" accesskey="9">ident option (-i)</a></td><td> </td><td align="left" valign="top"> 367</td></tr> 368<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-lifetime">lifetime option (-l)</a></td><td> </td><td align="left" valign="top"> 369</td></tr> 370<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-modulus">modulus option (-m)</a></td><td> </td><td align="left" valign="top"> 371</td></tr> 372<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-md5key">md5key option (-M)</a></td><td> </td><td align="left" valign="top"> 373</td></tr> 374<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-pvt_002dcert">pvt-cert option (-P)</a></td><td> </td><td align="left" valign="top"> 375</td></tr> 376<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-password">password option (-p)</a></td><td> </td><td align="left" valign="top"> 377</td></tr> 378<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-export_002dpasswd">export-passwd option (-q)</a></td><td> </td><td align="left" valign="top"> 379</td></tr> 380<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-subject_002dname">subject-name option (-s)</a></td><td> </td><td align="left" valign="top"> 381</td></tr> 382<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-sign_002dkey">sign-key option (-S)</a></td><td> </td><td align="left" valign="top"> 383</td></tr> 384<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-trusted_002dcert">trusted-cert option (-T)</a></td><td> </td><td align="left" valign="top"> 385</td></tr> 386<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-mv_002dparams">mv-params option (-V)</a></td><td> </td><td align="left" valign="top"> 387</td></tr> 388<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-mv_002dkeys">mv-keys option (-v)</a></td><td> </td><td align="left" valign="top"> 389</td></tr> 390<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-config">presetting/configuring ntp-keygen</a></td><td> </td><td align="left" valign="top"> 391</td></tr> 392<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-exit-status">ntp-keygen exit status</a></td><td> </td><td align="left" valign="top"> 393</td></tr> 394<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Usage">ntp-keygen Usage</a></td><td> </td><td align="left" valign="top"> 395</td></tr> 396<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Notes">ntp-keygen Notes</a></td><td> </td><td align="left" valign="top"> 397</td></tr> 398<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Bugs">ntp-keygen Bugs</a></td><td> </td><td align="left" valign="top"> 399</td></tr> 400</table> 401 402<span id="Running-the-Program-2"></span><h4 class="subsection">1.2.1 Running the Program</h4> 403<p>The safest way to run the 404<code>ntp-keygen</code> 405program is logged in directly as root. 406The recommended procedure is change to the 407<kbd>keys</kbd> 408directory, usually 409<samp>/usr/local/etc</samp>, 410then run the program. 411</p> 412<p>To test and gain experience with Autokey concepts, log in as root and 413change to the 414<kbd>keys</kbd> 415directory, usually 416<samp>/usr/local/etc</samp>. 417When run for the first time, or if all files with names beginning with 418<samp>ntpkey*</samp> 419have been removed, use the 420<code>ntp-keygen</code> 421command without arguments to generate a default 422<code>RSA</code> 423host key and matching 424<code>RSA-MD5</code> 425certificate file with expiration date one year hence, 426which is all that is necessary in many cases. 427The program also generates soft links from the generic names 428to the respective files. 429If run again without options, the program uses the 430existing keys and parameters and generates a new certificate file with 431new expiration date one year hence, and soft link. 432</p> 433<p>The host key is used to encrypt the cookie when required and so must be 434<code>RSA</code> 435type. 436By default, the host key is also the sign key used to encrypt signatures. 437When necessary, a different sign key can be specified and this can be 438either 439<code>RSA</code> 440or 441<code>DSA</code> 442type. 443By default, the message digest type is 444<code>MD5</code>, 445but any combination 446of sign key type and message digest type supported by the OpenSSL library 447can be specified, including those using the 448<code>AES128CMAC</code>, <code>MD2</code>, <code>MD5</code>, <code>MDC2</code>, <code>SHA</code>, <code>SHA1</code> 449and 450<code>RIPE160</code> 451message digest algorithms. 452However, the scheme specified in the certificate must be compatible 453with the sign key. 454Certificates using any digest algorithm are compatible with 455<code>RSA</code> 456sign keys; 457however, only 458<code>SHA</code> 459and 460<code>SHA1</code> 461certificates are compatible with 462<code>DSA</code> 463sign keys. 464</p> 465<p>Private/public key files and certificates are compatible with 466other OpenSSL applications and very likely other libraries as well. 467Certificates or certificate requests derived from them should be compatible 468with extant industry practice, although some users might find 469the interpretation of X509v3 extension fields somewhat liberal. 470However, the identification parameter files, although encoded 471as the other files, are probably not compatible with anything other than Autokey. 472</p> 473<p>Running the program as other than root and using the Unix 474<code>su(1)</code> 475command 476to assume root may not work properly, since by default the OpenSSL library 477looks for the random seed file 478<samp>.rnd</samp> 479in the user home directory. 480However, there should be only one 481<samp>.rnd</samp>, 482most conveniently 483in the root directory, so it is convenient to define the 484.Ev RANDFILE 485environment variable used by the OpenSSL library as the path to 486<samp>.rnd</samp>. 487</p> 488<p>Installing the keys as root might not work in NFS-mounted 489shared file systems, as NFS clients may not be able to write 490to the shared keys directory, even as root. 491In this case, NFS clients can specify the files in another 492directory such as 493<samp>/etc</samp> 494using the 495<code>keysdir</code> 496<code>ntpd(1ntpdmdoc)</code> 497configuration file command. 498There is no need for one client to read the keys and certificates 499of other clients or servers, as these data are obtained automatically 500by the Autokey protocol. 501</p> 502<p>Ordinarily, cryptographic files are generated by the host that uses them, 503but it is possible for a trusted agent (TA) to generate these files 504for other hosts; however, in such cases files should always be encrypted. 505The subject name and trusted name default to the hostname 506of the host generating the files, but can be changed by command line options. 507It is convenient to designate the owner name and trusted name 508as the subject and issuer fields, respectively, of the certificate. 509The owner name is also used for the host and sign key files, 510while the trusted name is used for the identity files. 511</p> 512<p>All files are installed by default in the keys directory 513<samp>/usr/local/etc</samp>, 514which is normally in a shared filesystem 515in NFS-mounted networks. 516The actual location of the keys directory 517and each file can be overridden by configuration commands, 518but this is not recommended. 519Normally, the files for each host are generated by that host 520and used only by that host, although exceptions exist 521as noted later on this page. 522</p> 523<p>Normally, files containing private values, 524including the host key, sign key and identification parameters, 525are permitted root read/write-only; 526while others containing public values are permitted world readable. 527Alternatively, files containing private values can be encrypted 528and these files permitted world readable, 529which simplifies maintenance in shared file systems. 530Since uniqueness is insured by the 531<kbd>hostname</kbd> 532and 533<kbd>filestamp</kbd> 534file name extensions, the files for an NTP server and 535dependent clients can all be installed in the same shared directory. 536</p> 537<p>The recommended practice is to keep the file name extensions 538when installing a file and to install a soft link 539from the generic names specified elsewhere on this page 540to the generated files. 541This allows new file generations to be activated simply 542by changing the link. 543If a link is present, 544<code>ntpd(1ntpdmdoc)</code> 545follows it to the file name to extract the 546<kbd>filestamp</kbd>. 547If a link is not present, 548<code>ntpd(1ntpdmdoc)</code> 549extracts the 550<kbd>filestamp</kbd> 551from the file itself. 552This allows clients to verify that the file and generation times 553are always current. 554The 555<code>ntp-keygen</code> 556program uses the same 557<kbd>filestamp</kbd> 558extension for all files generated 559at one time, so each generation is distinct and can be readily 560recognized in monitoring data. 561</p> 562<p>Run the command on as many hosts as necessary. 563Designate one of them as the trusted host (TH) using 564<code>ntp-keygen</code> 565with the 566<code>-T</code> 567option and configure it to synchronize from reliable Internet servers. 568Then configure the other hosts to synchronize to the TH directly or 569indirectly. 570A certificate trail is created when Autokey asks the immediately 571ascendant host towards the TH to sign its certificate, which is then 572provided to the immediately descendant host on request. 573All group hosts should have acyclic certificate trails ending on the TH. 574</p> 575<p>The host key is used to encrypt the cookie when required and so must be 576RSA type. 577By default, the host key is also the sign key used to encrypt 578signatures. 579A different sign key can be assigned using the 580<code>-S</code> 581option and this can be either 582<code>RSA</code> 583or 584<code>DSA</code> 585type. 586By default, the signature 587message digest type is 588<code>MD5</code>, 589but any combination of sign key type and 590message digest type supported by the OpenSSL library can be specified 591using the 592<code>-c</code> 593option. 594</p> 595<p>The rules say cryptographic media should be generated with proventic 596filestamps, which means the host should already be synchronized before 597this program is run. 598This of course creates a chicken-and-egg problem 599when the host is started for the first time. 600Accordingly, the host time 601should be set by some other means, such as eyeball-and-wristwatch, at 602least so that the certificate lifetime is within the current year. 603After that and when the host is synchronized to a proventic source, the 604certificate should be re-generated. 605</p> 606<p>Additional information on trusted groups and identity schemes is on the 607“Autokey Public-Key Authentication” 608page. 609</p> 610<p>File names begin with the prefix 611<samp>ntpkey</samp>_ 612and end with the suffix 613<samp>_</samp><kbd>hostname</kbd>. <kbd>filestamp</kbd>, 614where 615<kbd>hostname</kbd> 616is the owner name, usually the string returned 617by the Unix 618<code>hostname(1)</code> 619command, and 620<kbd>filestamp</kbd> 621is the NTP seconds when the file was generated, in decimal digits. 622This both guarantees uniqueness and simplifies maintenance 623procedures, since all files can be quickly removed 624by a 625<code>rm</code> <samp>ntpkey*</samp> 626command or all files generated 627at a specific time can be removed by a 628<code>rm</code> <samp>*</samp><kbd>filestamp</kbd> 629command. 630To further reduce the risk of misconfiguration, 631the first two lines of a file contain the file name 632and generation date and time as comments. 633</p> 634<span id="Trusted-Hosts-and-Groups"></span><h4 class="subsubsection">1.2.1.1 Trusted Hosts and Groups</h4> 635<p>Each cryptographic configuration involves selection of a signature scheme 636and identification scheme, called a cryptotype, 637as explained in the 638‘Authentication Options’ 639section of 640<code>ntp.conf(5)</code>. 641The default cryptotype uses 642<code>RSA</code> 643encryption, 644<code>MD5</code> 645message digest 646and 647<code>TC</code> 648identification. 649First, configure a NTP subnet including one or more low-stratum 650trusted hosts from which all other hosts derive synchronization 651directly or indirectly. 652Trusted hosts have trusted certificates; 653all other hosts have nontrusted certificates. 654These hosts will automatically and dynamically build authoritative 655certificate trails to one or more trusted hosts. 656A trusted group is the set of all hosts that have, directly or indirectly, 657a certificate trail ending at a trusted host. 658The trail is defined by static configuration file entries 659or dynamic means described on the 660‘Automatic NTP Configuration Options’ 661section of 662<code>ntp.conf(5)</code>. 663</p> 664<p>On each trusted host as root, change to the keys directory. 665To insure a fresh fileset, remove all 666<samp>ntpkey</samp> 667files. 668Then run 669<code>ntp-keygen</code> 670<code>-T</code> 671to generate keys and a trusted certificate. 672On all other hosts do the same, but leave off the 673<code>-T</code> 674flag to generate keys and nontrusted certificates. 675When complete, start the NTP daemons beginning at the lowest stratum 676and working up the tree. 677It may take some time for Autokey to instantiate the certificate trails 678throughout the subnet, but setting up the environment is completely automatic. 679</p> 680<p>If it is necessary to use a different sign key or different digest/signature 681scheme than the default, run 682<code>ntp-keygen</code> 683with the 684<code>-S</code> <kbd>type</kbd> 685option, where 686<kbd>type</kbd> 687is either 688<code>RSA</code> 689or 690<code>DSA</code>. 691The most frequent need to do this is when a 692<code>DSA</code>-signed 693certificate is used. 694If it is necessary to use a different certificate scheme than the default, 695run 696<code>ntp-keygen</code> 697with the 698<code>-c</code> <kbd>scheme</kbd> 699option and selected 700<kbd>scheme</kbd> 701as needed. 702If 703<code>ntp-keygen</code> 704is run again without these options, it generates a new certificate 705using the same scheme and sign key, and soft link. 706</p> 707<p>After setting up the environment it is advisable to update certificates 708from time to time, if only to extend the validity interval. 709Simply run 710<code>ntp-keygen</code> 711with the same flags as before to generate new certificates 712using existing keys, and soft links. 713However, if the host or sign key is changed, 714<code>ntpd(1ntpdmdoc)</code> 715should be restarted. 716When 717<code>ntpd(1ntpdmdoc)</code> 718is restarted, it loads any new files and restarts the protocol. 719Other dependent hosts will continue as usual until signatures are refreshed, 720at which time the protocol is restarted. 721</p> 722<span id="Identity-Schemes"></span><h4 class="subsubsection">1.2.1.2 Identity Schemes</h4> 723<p>As mentioned on the Autonomous Authentication page, 724the default 725<code>TC</code> 726identity scheme is vulnerable to a middleman attack. 727However, there are more secure identity schemes available, 728including 729<code>PC</code>, <code>IFF</code>, <code>GQ</code> 730and 731<code>MV</code> 732schemes described below. 733These schemes are based on a TA, one or more trusted hosts 734and some number of nontrusted hosts. 735Trusted hosts prove identity using values provided by the TA, 736while the remaining hosts prove identity using values provided 737by a trusted host and certificate trails that end on that host. 738The name of a trusted host is also the name of its sugroup 739and also the subject and issuer name on its trusted certificate. 740The TA is not necessarily a trusted host in this sense, but often is. 741</p> 742<p>In some schemes there are separate keys for servers and clients. 743A server can also be a client of another server, 744but a client can never be a server for another client. 745In general, trusted hosts and nontrusted hosts that operate 746as both server and client have parameter files that contain 747both server and client keys. 748Hosts that operate 749only as clients have key files that contain only client keys. 750</p> 751<p>The PC scheme supports only one trusted host in the group. 752On trusted host alice run 753<code>ntp-keygen</code> 754<code>-P</code> 755<code>-p</code> <kbd>password</kbd> 756to generate the host key file 757<samp>ntpkey</samp>_ <code>RSA</code> <samp>key_alice.</samp> <kbd>filestamp</kbd> 758and trusted private certificate file 759<samp>ntpkey</samp>_ <code>RSA-MD5</code> <code>_</code> <samp>cert_alice.</samp> <kbd>filestamp</kbd>, 760and soft links. 761Copy both files to all group hosts; 762they replace the files which would be generated in other schemes. 763On each host 764<kbd>bob</kbd> 765install a soft link from the generic name 766<samp>ntpkey_host_</samp><kbd>bob</kbd> 767to the host key file and soft link 768<samp>ntpkey_cert_</samp><kbd>bob</kbd> 769to the private certificate file. 770Note the generic links are on bob, but point to files generated 771by trusted host alice. 772In this scheme it is not possible to refresh 773either the keys or certificates without copying them 774to all other hosts in the group, and recreating the soft links. 775</p> 776<p>For the 777<code>IFF</code> 778scheme proceed as in the 779<code>TC</code> 780scheme to generate keys 781and certificates for all group hosts, then for every trusted host in the group, 782generate the 783<code>IFF</code> 784parameter file. 785On trusted host alice run 786<code>ntp-keygen</code> 787<code>-T</code> 788<code>-I</code> 789<code>-p</code> <kbd>password</kbd> 790to produce her parameter file 791<samp>ntpkey_IFFpar_alice.</samp><kbd>filestamp</kbd>, 792which includes both server and client keys. 793Copy this file to all group hosts that operate as both servers 794and clients and install a soft link from the generic 795<samp>ntpkey_iff_alice</samp> 796to this file. 797If there are no hosts restricted to operate only as clients, 798there is nothing further to do. 799As the 800<code>IFF</code> 801scheme is independent 802of keys and certificates, these files can be refreshed as needed. 803</p> 804<p>If a rogue client has the parameter file, it could masquerade 805as a legitimate server and present a middleman threat. 806To eliminate this threat, the client keys can be extracted 807from the parameter file and distributed to all restricted clients. 808After generating the parameter file, on alice run 809<code>ntp-keygen</code> 810<code>-e</code> 811and pipe the output to a file or email program. 812Copy or email this file to all restricted clients. 813On these clients install a soft link from the generic 814<samp>ntpkey_iff_alice</samp> 815to this file. 816To further protect the integrity of the keys, 817each file can be encrypted with a secret password. 818</p> 819<p>For the 820<code>GQ</code> 821scheme proceed as in the 822<code>TC</code> 823scheme to generate keys 824and certificates for all group hosts, then for every trusted host 825in the group, generate the 826<code>IFF</code> 827parameter file. 828On trusted host alice run 829<code>ntp-keygen</code> 830<code>-T</code> 831<code>-G</code> 832<code>-p</code> <kbd>password</kbd> 833to produce her parameter file 834<samp>ntpkey_GQpar_alice.</samp><kbd>filestamp</kbd>, 835which includes both server and client keys. 836Copy this file to all group hosts and install a soft link 837from the generic 838<samp>ntpkey_gq_alice</samp> 839to this file. 840In addition, on each host 841<kbd>bob</kbd> 842install a soft link 843from generic 844<samp>ntpkey_gq_</samp><kbd>bob</kbd> 845to this file. 846As the 847<code>GQ</code> 848scheme updates the 849<code>GQ</code> 850parameters file and certificate 851at the same time, keys and certificates can be regenerated as needed. 852</p> 853<p>For the 854<code>MV</code> 855scheme, proceed as in the 856<code>TC</code> 857scheme to generate keys 858and certificates for all group hosts. 859For illustration assume trish is the TA, alice one of several trusted hosts 860and bob one of her clients. 861On TA trish run 862<code>ntp-keygen</code> 863<code>-V</code> <kbd>n</kbd> 864<code>-p</code> <kbd>password</kbd>, 865where 866<kbd>n</kbd> 867is the number of revokable keys (typically 5) to produce 868the parameter file 869<samp>ntpkeys_MVpar_trish.</samp><kbd>filestamp</kbd> 870and client key files 871<samp>ntpkeys_MVkey</samp><kbd>d</kbd> <kbd>_</kbd> <samp>trish.</samp> <kbd>filestamp</kbd> 872where 873<kbd>d</kbd> 874is the key number (0 < 875<kbd>d</kbd> 876< 877<kbd>n</kbd>). 878Copy the parameter file to alice and install a soft link 879from the generic 880<samp>ntpkey_mv_alice</samp> 881to this file. 882Copy one of the client key files to alice for later distribution 883to her clients. 884It does not matter which client key file goes to alice, 885since they all work the same way. 886Alice copies the client key file to all of her clients. 887On client bob install a soft link from generic 888<samp>ntpkey_mvkey_bob</samp> 889to the client key file. 890As the 891<code>MV</code> 892scheme is independent of keys and certificates, 893these files can be refreshed as needed. 894</p> 895<span id="Command-Line-Options"></span><h4 class="subsubsection">1.2.1.3 Command Line Options</h4> 896<dl compact="compact"> 897<dt><code>-b</code> <code>--imbits</code>= <kbd>modulus</kbd></dt> 898<dd><p>Set the number of bits in the identity modulus for generating identity keys to 899<kbd>modulus</kbd> 900bits. 901The number of bits in the identity modulus defaults to 256, but can be set to 902values from 256 to 2048 (32 to 256 octets). 903Use the larger moduli with caution, as this can consume considerable computing 904resources and increases the size of authenticated packets. 905</p></dd> 906<dt><code>-c</code> <code>--certificate</code>= <kbd>scheme</kbd></dt> 907<dd><p>Select certificate signature encryption/message digest scheme. 908The 909<kbd>scheme</kbd> 910can be one of the following: 911<code>RSA-MD2</code>, <code>RSA-MD5</code>, <code>RSA-MDC2</code>, <code>RSA-SHA</code>, <code>RSA-SHA1</code>, <code>RSA-RIPEMD160</code>, <code>DSA-SHA</code>, 912or 913<code>DSA-SHA1</code>. 914Note that 915<code>RSA</code> 916schemes must be used with an 917<code>RSA</code> 918sign key and 919<code>DSA</code> 920schemes must be used with a 921<code>DSA</code> 922sign key. 923The default without this option is 924<code>RSA-MD5</code>. 925If compatibility with FIPS 140-2 is required, either the 926<code>DSA-SHA</code> 927or 928<code>DSA-SHA1</code> 929scheme must be used. 930</p></dd> 931<dt><code>-C</code> <code>--cipher</code>= <kbd>cipher</kbd></dt> 932<dd><p>Select the OpenSSL cipher to encrypt the files containing private keys. 933The default without this option is three-key triple DES in CBC mode, 934<code>des-ede3-cbc</code>. 935The 936<code>openssl</code> <code>-h</code> 937command provided with OpenSSL displays available ciphers. 938</p></dd> 939<dt><code>-d</code> <code>--debug-level</code></dt> 940<dd><p>Increase debugging verbosity level. 941This option displays the cryptographic data produced in eye-friendly billboards. 942</p></dd> 943<dt><code>-D</code> <code>--set-debug-level</code>= <kbd>level</kbd></dt> 944<dd><p>Set the debugging verbosity to 945<kbd>level</kbd>. 946This option displays the cryptographic data produced in eye-friendly billboards. 947</p></dd> 948<dt><code>-e</code> <code>--id-key</code></dt> 949<dd><p>Write the 950<code>IFF</code> 951or 952<code>GQ</code> 953public parameters from the 954<kbd>IFFkey</kbd> <kbd>or</kbd> <kbd>GQkey</kbd> 955client keys file previously specified 956as unencrypted data to the standard output stream 957<samp>stdout</samp>. 958This is intended for automatic key distribution by email. 959</p></dd> 960<dt><code>-G</code> <code>--gq-params</code></dt> 961<dd><p>Generate a new encrypted 962<code>GQ</code> 963parameters and key file for the Guillou-Quisquater (GQ) identity scheme. 964This option is mutually exclusive with the 965<code>-I</code> 966and 967<code>-V</code> 968options. 969</p></dd> 970<dt><code>-H</code> <code>--host-key</code></dt> 971<dd><p>Generate a new encrypted 972<code>RSA</code> 973public/private host key file. 974</p></dd> 975<dt><code>-I</code> <code>--iffkey</code></dt> 976<dd><p>Generate a new encrypted 977<code>IFF</code> 978key file for the Schnorr (IFF) identity scheme. 979This option is mutually exclusive with the 980<code>-G</code> 981and 982Fl V 983options. 984</p></dd> 985<dt><code>-i</code> <code>--ident</code>= <kbd>group</kbd></dt> 986<dd><p>Set the optional Autokey group name to 987<kbd>group</kbd>. 988This is used in the identity scheme parameter file names of 989<code>IFF</code>, <code>GQ</code>, 990and 991<code>MV</code> 992client parameters files. 993In that role, the default is the host name if no group is provided. 994The group name, if specified using 995<code>-i</code> 996or 997<code>-s</code> 998following an 999‘@’ 1000character, is also used in certificate subject and issuer names in the form 1001<kbd>host</kbd> <kbd>@</kbd> <kbd>group</kbd> 1002and should match the group specified via 1003<code>crypto</code> <code>ident</code> 1004or 1005<code>server</code> <code>ident</code> 1006in the ntpd configuration file. 1007</p></dd> 1008<dt><code>-l</code> <code>--lifetime</code>= <kbd>days</kbd></dt> 1009<dd><p>Set the lifetime for certificate expiration to 1010<kbd>days</kbd>. 1011The default lifetime is one year (365 days). 1012</p></dd> 1013<dt><code>-m</code> <code>--modulus</code>= <kbd>bits</kbd></dt> 1014<dd><p>Set the number of bits in the prime modulus for generating files to 1015<kbd>bits</kbd>. 1016The modulus defaults to 512, but can be set from 256 to 2048 (32 to 256 octets). 1017Use the larger moduli with caution, as this can consume considerable computing 1018resources and increases the size of authenticated packets. 1019</p></dd> 1020<dt><code>-M</code> <code>--md5key</code></dt> 1021<dd><p>Generate a new symmetric keys file containing 10 1022<code>MD5</code> 1023keys, and if OpenSSL is available, 10 1024<code>SHA</code> 1025keys. 1026An 1027<code>MD5</code> 1028key is a string of 20 random printable ASCII characters, while a 1029<code>SHA</code> 1030key is a string of 40 random hex digits. 1031The file can be edited using a text editor to change the key type or key content. 1032This option is mutually exclusive with all other options. 1033</p></dd> 1034<dt><code>-p</code> <code>--password</code>= <kbd>passwd</kbd></dt> 1035<dd><p>Set the password for reading and writing encrypted files to 1036<kbd>passwd</kbd>. 1037These include the host, sign and identify key files. 1038By default, the password is the string returned by the Unix 1039<code>hostname</code> 1040command. 1041</p></dd> 1042<dt><code>-P</code> <code>--pvt-cert</code></dt> 1043<dd><p>Generate a new private certificate used by the 1044<code>PC</code> 1045identity scheme. 1046By default, the program generates public certificates. 1047Note: the PC identity scheme is not recommended for new installations. 1048</p></dd> 1049<dt><code>-q</code> <code>--export-passwd</code>= <kbd>passwd</kbd></dt> 1050<dd><p>Set the password for writing encrypted 1051<code>IFF</code>, <code>GQ</code> <code>and</code> <code>MV</code> 1052identity files redirected to 1053<samp>stdout</samp> 1054to 1055<kbd>passwd</kbd>. 1056In effect, these files are decrypted with the 1057<code>-p</code> 1058password, then encrypted with the 1059<code>-q</code> 1060password. 1061By default, the password is the string returned by the Unix 1062<code>hostname</code> 1063command. 1064</p></dd> 1065<dt><code>-s</code> <code>--subject-key</code>= <code>[host]</code> <code>[@ <kbd>group</kbd>]</code></dt> 1066<dd><p>Specify the Autokey host name, where 1067<kbd>host</kbd> 1068is the optional host name and 1069<kbd>group</kbd> 1070is the optional group name. 1071The host name, and if provided, group name are used in 1072<kbd>host</kbd> <kbd>@</kbd> <kbd>group</kbd> 1073form as certificate subject and issuer. 1074Specifying 1075<code>-s</code> <code>-@</code> <kbd>group</kbd> 1076is allowed, and results in leaving the host name unchanged, as with 1077<code>-i</code> <kbd>group</kbd>. 1078The group name, or if no group is provided, the host name are also used in the 1079file names of 1080<code>IFF</code>, <code>GQ</code>, 1081and 1082<code>MV</code> 1083identity scheme client parameter files. 1084If 1085<kbd>host</kbd> 1086is not specified, the default host name is the string returned by the Unix 1087<code>hostname</code> 1088command. 1089</p></dd> 1090<dt><code>-S</code> <code>--sign-key</code>= <code>[<code>RSA</code> | <code>DSA</code>]</code></dt> 1091<dd><p>Generate a new encrypted public/private sign key file of the specified type. 1092By default, the sign key is the host key and has the same type. 1093If compatibility with FIPS 140-2 is required, the sign key type must be 1094<code>DSA</code>. 1095</p></dd> 1096<dt><code>-T</code> <code>--trusted-cert</code></dt> 1097<dd><p>Generate a trusted certificate. 1098By default, the program generates a non-trusted certificate. 1099</p></dd> 1100<dt><code>-V</code> <code>--mv-params</code> <kbd>nkeys</kbd></dt> 1101<dd><p>Generate 1102<kbd>nkeys</kbd> 1103encrypted server keys and parameters for the Mu-Varadharajan (MV) 1104identity scheme. 1105This option is mutually exclusive with the 1106<code>-I</code> 1107and 1108<code>-G</code> 1109options. 1110Note: support for this option should be considered a work in progress. 1111</p></dd> 1112</dl> 1113 1114<span id="Random-Seed-File-1"></span><h4 class="subsubsection">1.2.1.4 Random Seed File</h4> 1115<p>All cryptographically sound key generation schemes must have means 1116to randomize the entropy seed used to initialize 1117the internal pseudo-random number generator used 1118by the library routines. 1119The OpenSSL library uses a designated random seed file for this purpose. 1120The file must be available when starting the NTP daemon and 1121<code>ntp-keygen</code> 1122program. 1123If a site supports OpenSSL or its companion OpenSSH, 1124it is very likely that means to do this are already available. 1125</p> 1126<p>It is important to understand that entropy must be evolved 1127for each generation, for otherwise the random number sequence 1128would be predictable. 1129Various means dependent on external events, such as keystroke intervals, 1130can be used to do this and some systems have built-in entropy sources. 1131Suitable means are described in the OpenSSL software documentation, 1132but are outside the scope of this page. 1133</p> 1134<p>The entropy seed used by the OpenSSL library is contained in a file, 1135usually called 1136<samp>.rnd</samp>, 1137which must be available when starting the NTP daemon 1138or the 1139<code>ntp-keygen</code> 1140program. 1141The NTP daemon will first look for the file 1142using the path specified by the 1143<code>randfile</code> 1144subcommand of the 1145<code>crypto</code> 1146configuration command. 1147If not specified in this way, or when starting the 1148<code>ntp-keygen</code> 1149program, 1150the OpenSSL library will look for the file using the path specified 1151by the 1152.Ev RANDFILE 1153environment variable in the user home directory, 1154whether root or some other user. 1155If the 1156.Ev RANDFILE 1157environment variable is not present, 1158the library will look for the 1159<samp>.rnd</samp> 1160file in the user home directory. 1161Since both the 1162<code>ntp-keygen</code> 1163program and 1164<code>ntpd(1ntpdmdoc)</code> 1165daemon must run as root, the logical place to put this file is in 1166<samp>/.rnd</samp> 1167or 1168<samp>/root/.rnd</samp>. 1169If the file is not available or cannot be written, 1170the daemon exits with a message to the system log and the program 1171exits with a suitable error message. 1172</p> 1173<span id="Cryptographic-Data-Files-1"></span><h4 class="subsubsection">1.2.1.5 Cryptographic Data Files</h4> 1174<p>All file formats begin with two nonencrypted lines. 1175The first line contains the file name, including the generated host name 1176and filestamp, in the format 1177<samp>ntpkey_</samp><kbd>key</kbd> <kbd>_</kbd> <kbd>name</kbd>. <kbd>filestamp</kbd>, 1178where 1179<kbd>key</kbd> 1180is the key or parameter type, 1181<kbd>name</kbd> 1182is the host or group name and 1183<kbd>filestamp</kbd> 1184is the filestamp (NTP seconds) when the file was created. 1185By convention, 1186<kbd>key</kbd> 1187names in generated file names include both upper and lower case 1188characters, while 1189<kbd>key</kbd> 1190names in generated link names include only lower case characters. 1191The filestamp is not used in generated link names. 1192The second line contains the datestamp in conventional Unix 1193<samp>date</samp> 1194format. 1195Lines beginning with 1196‘#’ 1197are considered comments and ignored by the 1198<code>ntp-keygen</code> 1199program and 1200<code>ntpd(1ntpdmdoc)</code> 1201daemon. 1202</p> 1203<p>The remainder of the file contains cryptographic data, encoded first using ASN.1 1204rules, then encrypted if necessary, and finally written in PEM-encoded 1205printable ASCII text, preceded and followed by MIME content identifier lines. 1206</p> 1207<p>The format of the symmetric keys file, ordinarily named 1208<samp>ntp.keys</samp>, 1209is somewhat different than the other files in the interest of backward compatibility. 1210Ordinarily, the file is generated by this program, but it can be constructed 1211and edited using an ordinary text editor. 1212</p><pre class="verbatim"># ntpkey_MD5key_bk.ntp.org.3595864945 1213# Thu Dec 12 19:22:25 2013 1214 12151 MD5 L";Nw<\`.I<f4U0)247"i # MD5 key 12162 MD5 &>l0%XXK9O'51VwV<xq~ # MD5 key 12173 MD5 lb4zLW~d^!K:]RsD'qb6 # MD5 key 12184 MD5 Yue:tL[+vR)M\`n~bY,'? # MD5 key 12195 MD5 B;fx'Kgr/&4ZTbL6=RxA # MD5 key 12206 MD5 4eYwa\`o@}3i@@@@V@@..R9!l # MD5 key 12217 MD5 \`A.([h+;wTQ|xfi%Sn_! # MD5 key 12228 MD5 45:V,r4]l6y^JH6"Sh?F # MD5 key 12239 MD5 3-5vcn*6l29DS?Xdsg)* # MD5 key 122410 MD5 2late4Me # MD5 key 122511 SHA1 a27872d3030a9025b8446c751b4551a7629af65c # SHA1 key 122612 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74 # SHA1 key 122713 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9 # SHA1 key 122814 SHA a5332809c8878dd3a5b918819108a111509aeceb # SHA key 122915 MD2 2fe16c88c760ff2f16d4267e36c1aa6c926e6964 # MD2 key 123016 MD4 b2691811dc19cfc0e2f9bcacd74213f29812183d # MD4 key 123117 MD5 e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c # MD5 key 123218 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc # MDC2 key 123319 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2 # RIPEMD160 key 123420 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878 # AES128CMAC key 1235</pre><div class="example"> 1236<pre class="example">Figure 1. Typical Symmetric Key File 1237</pre></div> 1238 1239<p>Figure 1 shows a typical symmetric keys file used by the reference 1240implementation. 1241Following the header the keys are entered one per line in the format 1242</p><div class="example"> 1243<pre class="example"><kbd>keyno</kbd> <kbd>type</kbd> <kbd>key</kbd> 1244</pre></div> 1245<p>where 1246<kbd>keyno</kbd> 1247is a positive integer in the range 1-65535; 1248<kbd>type</kbd> 1249is the key type for the message digest algorithm, which in the absence of the 1250OpenSSL library must be 1251<code>MD5</code> 1252to designate the MD5 message digest algorithm; 1253if the OpenSSL library is installed, the key type can be any 1254message digest algorithm supported by that library; 1255however, if compatibility with FIPS 140-2 is required, 1256the key type must be either 1257<code>SHA</code> 1258or 1259<code>SHA1</code>; 1260<kbd>key</kbd> 1261is the key itself, 1262which is a printable ASCII string 20 characters or less in length: 1263each character is chosen from the 93 printable characters 1264in the range 0x21 through 0x7e ( 1265‘’! 1266through 1267‘~’ 1268) excluding space and the 1269‘#’ 1270character, and terminated by whitespace or a 1271‘#’ 1272character. 1273An OpenSSL key consists of a hex-encoded ASCII string of 40 characters, which 1274is truncated as necessary. 1275</p> 1276<p>Note that the keys used by the 1277<code>ntpq(1ntpqmdoc)</code> 1278and 1279<code>ntpdc(1ntpdcmdoc)</code> 1280programs 1281are checked against passwords requested by the programs 1282and entered by hand, so it is generally appropriate to specify these keys 1283in human readable ASCII format. 1284</p> 1285<p>The 1286<code>ntp-keygen</code> 1287program generates a symmetric keys file 1288<samp>ntpkey_MD5key_</samp><kbd>hostname</kbd>. <kbd>filestamp</kbd>. 1289Since the file contains private shared keys, 1290it should be visible only to root and distributed by secure means 1291to other subnet hosts. 1292The NTP daemon loads the file 1293<samp>ntp.keys</samp>, 1294so 1295<code>ntp-keygen</code> 1296installs a soft link from this name to the generated file. 1297Subsequently, similar soft links must be installed by manual 1298or automated means on the other subnet hosts. 1299While this file is not used with the Autokey Version 2 protocol, 1300it is needed to authenticate some remote configuration commands 1301used by the 1302<code>ntpq(1ntpqmdoc)</code> 1303and 1304<code>ntpdc(1ntpdcmdoc)</code> 1305utilities. 1306</p> 1307<p>This section was generated by <strong>AutoGen</strong>, 1308using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntp-keygen</code> program. 1309This software is released under the NTP license, <http://ntp.org/license>. 1310</p> 1311<table class="menu" border="0" cellspacing="0"> 1312<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-usage" accesskey="1">ntp-keygen usage</a></td><td> </td><td align="left" valign="top">ntp-keygen help/usage (<samp>--help</samp>) 1313</td></tr> 1314<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-imbits" accesskey="2">ntp-keygen imbits</a></td><td> </td><td align="left" valign="top">imbits option (-b) 1315</td></tr> 1316<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-certificate" accesskey="3">ntp-keygen certificate</a></td><td> </td><td align="left" valign="top">certificate option (-c) 1317</td></tr> 1318<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-cipher" accesskey="4">ntp-keygen cipher</a></td><td> </td><td align="left" valign="top">cipher option (-C) 1319</td></tr> 1320<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-id_002dkey" accesskey="5">ntp-keygen id-key</a></td><td> </td><td align="left" valign="top">id-key option (-e) 1321</td></tr> 1322<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-gq_002dparams" accesskey="6">ntp-keygen gq-params</a></td><td> </td><td align="left" valign="top">gq-params option (-G) 1323</td></tr> 1324<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-host_002dkey" accesskey="7">ntp-keygen host-key</a></td><td> </td><td align="left" valign="top">host-key option (-H) 1325</td></tr> 1326<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-iffkey" accesskey="8">ntp-keygen iffkey</a></td><td> </td><td align="left" valign="top">iffkey option (-I) 1327</td></tr> 1328<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-ident" accesskey="9">ntp-keygen ident</a></td><td> </td><td align="left" valign="top">ident option (-i) 1329</td></tr> 1330<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-lifetime">ntp-keygen lifetime</a></td><td> </td><td align="left" valign="top">lifetime option (-l) 1331</td></tr> 1332<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-modulus">ntp-keygen modulus</a></td><td> </td><td align="left" valign="top">modulus option (-m) 1333</td></tr> 1334<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-md5key">ntp-keygen md5key</a></td><td> </td><td align="left" valign="top">md5key option (-M) 1335</td></tr> 1336<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-pvt_002dcert">ntp-keygen pvt-cert</a></td><td> </td><td align="left" valign="top">pvt-cert option (-P) 1337</td></tr> 1338<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-password">ntp-keygen password</a></td><td> </td><td align="left" valign="top">password option (-p) 1339</td></tr> 1340<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-export_002dpasswd">ntp-keygen export-passwd</a></td><td> </td><td align="left" valign="top">export-passwd option (-q) 1341</td></tr> 1342<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-subject_002dname">ntp-keygen subject-name</a></td><td> </td><td align="left" valign="top">subject-name option (-s) 1343</td></tr> 1344<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-sign_002dkey">ntp-keygen sign-key</a></td><td> </td><td align="left" valign="top">sign-key option (-S) 1345</td></tr> 1346<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-trusted_002dcert">ntp-keygen trusted-cert</a></td><td> </td><td align="left" valign="top">trusted-cert option (-T) 1347</td></tr> 1348<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-mv_002dparams">ntp-keygen mv-params</a></td><td> </td><td align="left" valign="top">mv-params option (-V) 1349</td></tr> 1350<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-mv_002dkeys">ntp-keygen mv-keys</a></td><td> </td><td align="left" valign="top">mv-keys option (-v) 1351</td></tr> 1352<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-config">ntp-keygen config</a></td><td> </td><td align="left" valign="top">presetting/configuring ntp-keygen 1353</td></tr> 1354<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-exit-status">ntp-keygen exit status</a></td><td> </td><td align="left" valign="top">exit status 1355</td></tr> 1356<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Usage">ntp-keygen Usage</a></td><td> </td><td align="left" valign="top">Usage 1357</td></tr> 1358<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Notes">ntp-keygen Notes</a></td><td> </td><td align="left" valign="top">Notes 1359</td></tr> 1360<tr><td align="left" valign="top">• <a href="#ntp_002dkeygen-Bugs">ntp-keygen Bugs</a></td><td> </td><td align="left" valign="top">Bugs 1361</td></tr> 1362</table> 1363 1364<hr> 1365<span id="ntp_002dkeygen-usage"></span><div class="header"> 1366<p> 1367Next: <a href="#ntp_002dkeygen-imbits" accesskey="n" rel="next">ntp-keygen imbits</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1368</div> 1369<span id="ntp_002dkeygen-help_002fusage-_0028_002d_002dhelp_0029"></span><h4 class="subsection">1.2.2 ntp-keygen help/usage (<samp>--help</samp>)</h4> 1370<span id="index-ntp_002dkeygen-help"></span> 1371 1372<p>This is the automatically generated usage text for ntp-keygen. 1373</p> 1374<p>The text printed is the same whether selected with the <code>help</code> option 1375(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>). <code>more-help</code> will print 1376the usage text by passing it through a pager program. 1377<code>more-help</code> is disabled on platforms without a working 1378<code>fork(2)</code> function. The <code>PAGER</code> environment variable is 1379used to select the program, defaulting to <samp>more</samp>. Both will exit 1380with a status code of 0. 1381</p> 1382<div class="example"> 1383<pre class="example">ntp-keygen (ntp) - Create a NTP host key - Ver. 4.2.8p17 1384Usage: ntp-keygen [ -<flag> [<val>] | --<name>[{=| }<val>] ]... 1385 Flg Arg Option-Name Description 1386 -b Num imbits identity modulus bits 1387 - it must be in the range: 1388 256 to 2048 1389 -c Str certificate certificate scheme 1390 -C Str cipher privatekey cipher 1391 -d no debug-level Increase debug verbosity level 1392 - may appear multiple times 1393 -D Num set-debug-level Set the debug verbosity level 1394 - may appear multiple times 1395 -e no id-key Write IFF or GQ identity keys 1396 -G no gq-params Generate GQ parameters and keys 1397 -H no host-key generate RSA host key 1398 -I no iffkey generate IFF parameters 1399 -i Str ident set Autokey group name 1400 -l Num lifetime set certificate lifetime 1401 -m Num modulus prime modulus 1402 - it must be in the range: 1403 256 to 2048 1404 -M no md5key generate symmetric keys 1405 -P no pvt-cert generate PC private certificate 1406 -p Str password local private password 1407 -q Str export-passwd export IFF or GQ group keys with password 1408 -s Str subject-name set host and optionally group name 1409 -S Str sign-key generate sign key (RSA or DSA) 1410 -T no trusted-cert trusted certificate (TC scheme) 1411 -V Num mv-params generate <num> MV parameters 1412 -v Num mv-keys update <num> MV keys 1413 opt version output version information and exit 1414 -? no help display extended usage information and exit 1415 -! no more-help extended usage information passed thru pager 1416 -> opt save-opts save the option state to a config file 1417 -< Str load-opts load options from a config file 1418 - disabled as '--no-load-opts' 1419 - may appear multiple times 1420 1421Options are specified by doubled hyphens and their name or by a single 1422hyphen and the flag character. 1423 1424 1425The following option preset mechanisms are supported: 1426 - reading file $HOME/.ntprc 1427 - reading file ./.ntprc 1428 - examining environment variables named NTP_KEYGEN_* 1429 1430Please send bug reports to: <https://bugs.ntp.org, bugs@ntp.org> 1431</pre></div> 1432 1433<hr> 1434<span id="ntp_002dkeygen-imbits"></span><div class="header"> 1435<p> 1436Next: <a href="#ntp_002dkeygen-certificate" accesskey="n" rel="next">ntp-keygen certificate</a>, Previous: <a href="#ntp_002dkeygen-usage" accesskey="p" rel="prev">ntp-keygen usage</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1437</div> 1438<span id="imbits-option-_0028_002db_0029"></span><h4 class="subsection">1.2.3 imbits option (-b)</h4> 1439<span id="index-ntp_002dkeygen_002dimbits"></span> 1440 1441<p>This is the “identity modulus bits” option. 1442This option takes a number argument <samp>imbits</samp>. 1443</p> 1444<p>This option has some usage constraints. It: 1445</p><ul> 1446<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1447</li></ul> 1448 1449<p>The number of bits in the identity modulus. The default is 512. 1450</p><hr> 1451<span id="ntp_002dkeygen-certificate"></span><div class="header"> 1452<p> 1453Next: <a href="#ntp_002dkeygen-cipher" accesskey="n" rel="next">ntp-keygen cipher</a>, Previous: <a href="#ntp_002dkeygen-imbits" accesskey="p" rel="prev">ntp-keygen imbits</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1454</div> 1455<span id="certificate-option-_0028_002dc_0029"></span><h4 class="subsection">1.2.4 certificate option (-c)</h4> 1456<span id="index-ntp_002dkeygen_002dcertificate"></span> 1457 1458<p>This is the “certificate scheme” option. 1459This option takes a string argument <samp>scheme</samp>. 1460</p> 1461<p>This option has some usage constraints. It: 1462</p><ul> 1463<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1464</li></ul> 1465 1466<p>scheme is one of 1467RSA-MD2, RSA-MD5, RSA-MDC2, RSA-SHA, RSA-SHA1, RSA-RIPEMD160, 1468DSA-SHA, or DSA-SHA1. 1469</p> 1470<p>Select the certificate signature encryption/message digest scheme. 1471Note that RSA schemes must be used with a RSA sign key and DSA 1472schemes must be used with a DSA sign key. The default without 1473this option is RSA-MD5. 1474</p><hr> 1475<span id="ntp_002dkeygen-cipher"></span><div class="header"> 1476<p> 1477Next: <a href="#ntp_002dkeygen-id_002dkey" accesskey="n" rel="next">ntp-keygen id-key</a>, Previous: <a href="#ntp_002dkeygen-certificate" accesskey="p" rel="prev">ntp-keygen certificate</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1478</div> 1479<span id="cipher-option-_0028_002dC_0029"></span><h4 class="subsection">1.2.5 cipher option (-C)</h4> 1480<span id="index-ntp_002dkeygen_002dcipher"></span> 1481 1482<p>This is the “privatekey cipher” option. 1483This option takes a string argument <samp>cipher</samp>. 1484</p> 1485<p>This option has some usage constraints. It: 1486</p><ul> 1487<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1488</li></ul> 1489 1490<p>Select the cipher which is used to encrypt the files containing 1491private keys. The default is three-key triple DES in CBC mode, 1492equivalent to "<code>-C des-ede3-cbc</code>". The openssl tool lists ciphers 1493available in "<code>openssl -h</code>" output. 1494</p><hr> 1495<span id="ntp_002dkeygen-id_002dkey"></span><div class="header"> 1496<p> 1497Next: <a href="#ntp_002dkeygen-gq_002dparams" accesskey="n" rel="next">ntp-keygen gq-params</a>, Previous: <a href="#ntp_002dkeygen-cipher" accesskey="p" rel="prev">ntp-keygen cipher</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1498</div> 1499<span id="id_002dkey-option-_0028_002de_0029"></span><h4 class="subsection">1.2.6 id-key option (-e)</h4> 1500<span id="index-ntp_002dkeygen_002did_002dkey"></span> 1501 1502<p>This is the “write iff or gq identity keys” option. 1503</p> 1504<p>This option has some usage constraints. It: 1505</p><ul> 1506<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1507</li></ul> 1508 1509<p>Write the public parameters from the IFF or GQ client keys to 1510the standard output. 1511This is intended for automatic key distribution by email. 1512</p><hr> 1513<span id="ntp_002dkeygen-gq_002dparams"></span><div class="header"> 1514<p> 1515Next: <a href="#ntp_002dkeygen-host_002dkey" accesskey="n" rel="next">ntp-keygen host-key</a>, Previous: <a href="#ntp_002dkeygen-id_002dkey" accesskey="p" rel="prev">ntp-keygen id-key</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1516</div> 1517<span id="gq_002dparams-option-_0028_002dG_0029"></span><h4 class="subsection">1.2.7 gq-params option (-G)</h4> 1518<span id="index-ntp_002dkeygen_002dgq_002dparams"></span> 1519 1520<p>This is the “generate gq parameters and keys” option. 1521</p> 1522<p>This option has some usage constraints. It: 1523</p><ul> 1524<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1525</li></ul> 1526 1527<p>Generate parameters and keys for the GQ identification scheme, 1528obsoleting any that may exist. 1529</p><hr> 1530<span id="ntp_002dkeygen-host_002dkey"></span><div class="header"> 1531<p> 1532Next: <a href="#ntp_002dkeygen-iffkey" accesskey="n" rel="next">ntp-keygen iffkey</a>, Previous: <a href="#ntp_002dkeygen-gq_002dparams" accesskey="p" rel="prev">ntp-keygen gq-params</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1533</div> 1534<span id="host_002dkey-option-_0028_002dH_0029"></span><h4 class="subsection">1.2.8 host-key option (-H)</h4> 1535<span id="index-ntp_002dkeygen_002dhost_002dkey"></span> 1536 1537<p>This is the “generate rsa host key” option. 1538</p> 1539<p>This option has some usage constraints. It: 1540</p><ul> 1541<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1542</li></ul> 1543 1544<p>Generate new host keys, obsoleting any that may exist. 1545</p><hr> 1546<span id="ntp_002dkeygen-iffkey"></span><div class="header"> 1547<p> 1548Next: <a href="#ntp_002dkeygen-ident" accesskey="n" rel="next">ntp-keygen ident</a>, Previous: <a href="#ntp_002dkeygen-host_002dkey" accesskey="p" rel="prev">ntp-keygen host-key</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1549</div> 1550<span id="iffkey-option-_0028_002dI_0029"></span><h4 class="subsection">1.2.9 iffkey option (-I)</h4> 1551<span id="index-ntp_002dkeygen_002diffkey"></span> 1552 1553<p>This is the “generate iff parameters” option. 1554</p> 1555<p>This option has some usage constraints. It: 1556</p><ul> 1557<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1558</li></ul> 1559 1560<p>Generate parameters for the IFF identification scheme, obsoleting 1561any that may exist. 1562</p><hr> 1563<span id="ntp_002dkeygen-ident"></span><div class="header"> 1564<p> 1565Next: <a href="#ntp_002dkeygen-lifetime" accesskey="n" rel="next">ntp-keygen lifetime</a>, Previous: <a href="#ntp_002dkeygen-iffkey" accesskey="p" rel="prev">ntp-keygen iffkey</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1566</div> 1567<span id="ident-option-_0028_002di_0029"></span><h4 class="subsection">1.2.10 ident option (-i)</h4> 1568<span id="index-ntp_002dkeygen_002dident"></span> 1569 1570<p>This is the “set autokey group name” option. 1571This option takes a string argument <samp>group</samp>. 1572</p> 1573<p>This option has some usage constraints. It: 1574</p><ul> 1575<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1576</li></ul> 1577 1578<p>Set the optional Autokey group name to name. This is used in 1579the file name of IFF, GQ, and MV client parameters files. In 1580that role, the default is the host name if this option is not 1581provided. The group name, if specified using <code>-i/--ident</code> or 1582using <code>-s/--subject-name</code> following an ’<code>@</code>’ character, 1583is also a part of the self-signed host certificate subject and 1584issuer names in the form <code>host@group</code> and should match the 1585’<code>crypto ident</code>’ or ’<code>server ident</code>’ configuration in the 1586<code>ntpd</code> configuration file. 1587</p><hr> 1588<span id="ntp_002dkeygen-lifetime"></span><div class="header"> 1589<p> 1590Next: <a href="#ntp_002dkeygen-modulus" accesskey="n" rel="next">ntp-keygen modulus</a>, Previous: <a href="#ntp_002dkeygen-ident" accesskey="p" rel="prev">ntp-keygen ident</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1591</div> 1592<span id="lifetime-option-_0028_002dl_0029"></span><h4 class="subsection">1.2.11 lifetime option (-l)</h4> 1593<span id="index-ntp_002dkeygen_002dlifetime"></span> 1594 1595<p>This is the “set certificate lifetime” option. 1596This option takes a number argument <samp>lifetime</samp>. 1597</p> 1598<p>This option has some usage constraints. It: 1599</p><ul> 1600<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1601</li></ul> 1602 1603<p>Set the certificate expiration to lifetime days from now. 1604</p><hr> 1605<span id="ntp_002dkeygen-modulus"></span><div class="header"> 1606<p> 1607Next: <a href="#ntp_002dkeygen-md5key" accesskey="n" rel="next">ntp-keygen md5key</a>, Previous: <a href="#ntp_002dkeygen-lifetime" accesskey="p" rel="prev">ntp-keygen lifetime</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1608</div> 1609<span id="modulus-option-_0028_002dm_0029"></span><h4 class="subsection">1.2.12 modulus option (-m)</h4> 1610<span id="index-ntp_002dkeygen_002dmodulus"></span> 1611 1612<p>This is the “prime modulus” option. 1613This option takes a number argument <samp>modulus</samp>. 1614</p> 1615<p>This option has some usage constraints. It: 1616</p><ul> 1617<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1618</li></ul> 1619 1620<p>The number of bits in the prime modulus. The default is 512. 1621</p><hr> 1622<span id="ntp_002dkeygen-md5key"></span><div class="header"> 1623<p> 1624Next: <a href="#ntp_002dkeygen-pvt_002dcert" accesskey="n" rel="next">ntp-keygen pvt-cert</a>, Previous: <a href="#ntp_002dkeygen-modulus" accesskey="p" rel="prev">ntp-keygen modulus</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1625</div> 1626<span id="md5key-option-_0028_002dM_0029"></span><h4 class="subsection">1.2.13 md5key option (-M)</h4> 1627<span id="index-ntp_002dkeygen_002dmd5key"></span> 1628 1629<p>This is the “generate symmetric keys” option. 1630Generate symmetric keys, obsoleting any that may exist. 1631</p><hr> 1632<span id="ntp_002dkeygen-pvt_002dcert"></span><div class="header"> 1633<p> 1634Next: <a href="#ntp_002dkeygen-password" accesskey="n" rel="next">ntp-keygen password</a>, Previous: <a href="#ntp_002dkeygen-md5key" accesskey="p" rel="prev">ntp-keygen md5key</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1635</div> 1636<span id="pvt_002dcert-option-_0028_002dP_0029"></span><h4 class="subsection">1.2.14 pvt-cert option (-P)</h4> 1637<span id="index-ntp_002dkeygen_002dpvt_002dcert"></span> 1638 1639<p>This is the “generate pc private certificate” option. 1640</p> 1641<p>This option has some usage constraints. It: 1642</p><ul> 1643<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1644</li></ul> 1645 1646<p>Generate a private certificate. By default, the program generates 1647public certificates. 1648</p><hr> 1649<span id="ntp_002dkeygen-password"></span><div class="header"> 1650<p> 1651Next: <a href="#ntp_002dkeygen-export_002dpasswd" accesskey="n" rel="next">ntp-keygen export-passwd</a>, Previous: <a href="#ntp_002dkeygen-pvt_002dcert" accesskey="p" rel="prev">ntp-keygen pvt-cert</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1652</div> 1653<span id="password-option-_0028_002dp_0029"></span><h4 class="subsection">1.2.15 password option (-p)</h4> 1654<span id="index-ntp_002dkeygen_002dpassword"></span> 1655 1656<p>This is the “local private password” option. 1657This option takes a string argument <samp>passwd</samp>. 1658</p> 1659<p>This option has some usage constraints. It: 1660</p><ul> 1661<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1662</li></ul> 1663 1664<p>Local files containing private data are encrypted with the 1665DES-CBC algorithm and the specified password. The same password 1666must be specified to the local ntpd via the "crypto pw password" 1667configuration command. The default password is the local 1668hostname. 1669</p><hr> 1670<span id="ntp_002dkeygen-export_002dpasswd"></span><div class="header"> 1671<p> 1672Next: <a href="#ntp_002dkeygen-subject_002dname" accesskey="n" rel="next">ntp-keygen subject-name</a>, Previous: <a href="#ntp_002dkeygen-password" accesskey="p" rel="prev">ntp-keygen password</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1673</div> 1674<span id="export_002dpasswd-option-_0028_002dq_0029"></span><h4 class="subsection">1.2.16 export-passwd option (-q)</h4> 1675<span id="index-ntp_002dkeygen_002dexport_002dpasswd"></span> 1676 1677<p>This is the “export iff or gq group keys with password” option. 1678This option takes a string argument <samp>passwd</samp>. 1679</p> 1680<p>This option has some usage constraints. It: 1681</p><ul> 1682<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1683</li></ul> 1684 1685<p>Export IFF or GQ identity group keys to the standard output, 1686encrypted with the DES-CBC algorithm and the specified password. 1687The same password must be specified to the remote ntpd via the 1688"crypto pw password" configuration command. See also the option 1689–id-key (-e) for unencrypted exports. 1690</p><hr> 1691<span id="ntp_002dkeygen-subject_002dname"></span><div class="header"> 1692<p> 1693Next: <a href="#ntp_002dkeygen-sign_002dkey" accesskey="n" rel="next">ntp-keygen sign-key</a>, Previous: <a href="#ntp_002dkeygen-export_002dpasswd" accesskey="p" rel="prev">ntp-keygen export-passwd</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1694</div> 1695<span id="subject_002dname-option-_0028_002ds_0029"></span><h4 class="subsection">1.2.17 subject-name option (-s)</h4> 1696<span id="index-ntp_002dkeygen_002dsubject_002dname"></span> 1697 1698<p>This is the “set host and optionally group name” option. 1699This option takes a string argument <samp>host@group</samp>. 1700</p> 1701<p>This option has some usage constraints. It: 1702</p><ul> 1703<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1704</li></ul> 1705 1706<p>Set the Autokey host name, and optionally, group name specified 1707following an ’<code>@</code>’ character. The host name is used in the file 1708name of generated host and signing certificates, without the 1709group name. The host name, and if provided, group name are used 1710in <code>host@group</code> form for the host certificate subject and issuer 1711fields. Specifying ’<code>-s @group</code>’ is allowed, and results in 1712leaving the host name unchanged while appending <code>@group</code> to the 1713subject and issuer fields, as with <code>-i group</code>. The group name, or 1714if not provided, the host name are also used in the file names 1715of IFF, GQ, and MV client parameter files. 1716</p><hr> 1717<span id="ntp_002dkeygen-sign_002dkey"></span><div class="header"> 1718<p> 1719Next: <a href="#ntp_002dkeygen-trusted_002dcert" accesskey="n" rel="next">ntp-keygen trusted-cert</a>, Previous: <a href="#ntp_002dkeygen-subject_002dname" accesskey="p" rel="prev">ntp-keygen subject-name</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1720</div> 1721<span id="sign_002dkey-option-_0028_002dS_0029"></span><h4 class="subsection">1.2.18 sign-key option (-S)</h4> 1722<span id="index-ntp_002dkeygen_002dsign_002dkey"></span> 1723 1724<p>This is the “generate sign key (rsa or dsa)” option. 1725This option takes a string argument <samp>sign</samp>. 1726</p> 1727<p>This option has some usage constraints. It: 1728</p><ul> 1729<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1730</li></ul> 1731 1732<p>Generate a new sign key of the designated type, obsoleting any 1733that may exist. By default, the program uses the host key as the 1734sign key. 1735</p><hr> 1736<span id="ntp_002dkeygen-trusted_002dcert"></span><div class="header"> 1737<p> 1738Next: <a href="#ntp_002dkeygen-mv_002dparams" accesskey="n" rel="next">ntp-keygen mv-params</a>, Previous: <a href="#ntp_002dkeygen-sign_002dkey" accesskey="p" rel="prev">ntp-keygen sign-key</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1739</div> 1740<span id="trusted_002dcert-option-_0028_002dT_0029"></span><h4 class="subsection">1.2.19 trusted-cert option (-T)</h4> 1741<span id="index-ntp_002dkeygen_002dtrusted_002dcert"></span> 1742 1743<p>This is the “trusted certificate (tc scheme)” option. 1744</p> 1745<p>This option has some usage constraints. It: 1746</p><ul> 1747<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1748</li></ul> 1749 1750<p>Generate a trusted certificate. By default, the program generates 1751a non-trusted certificate. 1752</p><hr> 1753<span id="ntp_002dkeygen-mv_002dparams"></span><div class="header"> 1754<p> 1755Next: <a href="#ntp_002dkeygen-mv_002dkeys" accesskey="n" rel="next">ntp-keygen mv-keys</a>, Previous: <a href="#ntp_002dkeygen-trusted_002dcert" accesskey="p" rel="prev">ntp-keygen trusted-cert</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1756</div> 1757<span id="mv_002dparams-option-_0028_002dV_0029"></span><h4 class="subsection">1.2.20 mv-params option (-V)</h4> 1758<span id="index-ntp_002dkeygen_002dmv_002dparams"></span> 1759 1760<p>This is the “generate <num> mv parameters” option. 1761This option takes a number argument <samp>num</samp>. 1762</p> 1763<p>This option has some usage constraints. It: 1764</p><ul> 1765<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1766</li></ul> 1767 1768<p>Generate parameters and keys for the Mu-Varadharajan (MV) 1769identification scheme. 1770</p><hr> 1771<span id="ntp_002dkeygen-mv_002dkeys"></span><div class="header"> 1772<p> 1773Next: <a href="#ntp_002dkeygen-config" accesskey="n" rel="next">ntp-keygen config</a>, Previous: <a href="#ntp_002dkeygen-mv_002dparams" accesskey="p" rel="prev">ntp-keygen mv-params</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1774</div> 1775<span id="mv_002dkeys-option-_0028_002dv_0029"></span><h4 class="subsection">1.2.21 mv-keys option (-v)</h4> 1776<span id="index-ntp_002dkeygen_002dmv_002dkeys"></span> 1777 1778<p>This is the “update <num> mv keys” option. 1779This option takes a number argument <samp>num</samp>. 1780</p> 1781<p>This option has some usage constraints. It: 1782</p><ul> 1783<li> must be compiled in by defining <code>AUTOKEY</code> during the compilation. 1784</li></ul> 1785 1786<p>This option has no ‘<samp>doc</samp>’ documentation. 1787</p> 1788 1789<hr> 1790<span id="ntp_002dkeygen-config"></span><div class="header"> 1791<p> 1792Next: <a href="#ntp_002dkeygen-exit-status" accesskey="n" rel="next">ntp-keygen exit status</a>, Previous: <a href="#ntp_002dkeygen-mv_002dkeys" accesskey="p" rel="prev">ntp-keygen mv-keys</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1793</div> 1794<span id="presetting_002fconfiguring-ntp_002dkeygen"></span><h4 class="subsection">1.2.22 presetting/configuring ntp-keygen</h4> 1795 1796<p>Any option that is not marked as <i>not presettable</i> may be preset by 1797loading 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 1798the options listed above in upper case and segmented with underscores. 1799The <code>NTP-KEYGEN</code> variable will be tokenized and parsed like 1800the command line. The remaining variables are tested for existence and their 1801values are treated like option arguments. 1802</p> 1803 1804<p><code>libopts</code> will search in 2 places for configuration files: 1805</p><ul> 1806<li> $HOME 1807</li><li> $PWD 1808</li></ul> 1809<p>The environment variables <code>HOME</code>, and <code>PWD</code> 1810are expanded and replaced when <samp>ntp-keygen</samp> runs. 1811For any of these that are plain files, they are simply processed. 1812For any that are directories, then a file named <samp>.ntprc</samp> is searched for 1813within that directory and processed. 1814</p> 1815<p>Configuration files may be in a wide variety of formats. 1816The basic format is an option name followed by a value (argument) on the 1817same line. Values may be separated from the option name with a colon, 1818equal sign or simply white space. Values may be continued across multiple 1819lines by escaping the newline with a backslash. 1820</p> 1821<p>Multiple programs may also share the same initialization file. 1822Common options are collected at the top, followed by program specific 1823segments. The segments are separated by lines like: 1824</p><div class="example"> 1825<pre class="example">[NTP-KEYGEN] 1826</pre></div> 1827<p>or by 1828</p><div class="example"> 1829<pre class="example"><?program ntp-keygen> 1830</pre></div> 1831<p>Do not mix these styles within one configuration file. 1832</p> 1833<p>Compound values and carefully constructed string values may also be 1834specified using XML syntax: 1835</p><div class="example"> 1836<pre class="example"><option-name> 1837 <sub-opt>...&lt;...&gt;...</sub-opt> 1838</option-name> 1839</pre></div> 1840<p>yielding an <code>option-name.sub-opt</code> string value of 1841</p><div class="example"> 1842<pre class="example">"...<...>..." 1843</pre></div> 1844<p><code>AutoOpts</code> does not track suboptions. You simply note that it is a 1845hierarchicly valued option. <code>AutoOpts</code> does provide a means for searching 1846the associated name/value pair list (see: optionFindValue). 1847</p> 1848<p>The command line options relating to configuration and/or usage help are: 1849</p> 1850<span id="version-_0028_002d_0029"></span><h4 class="subsubheading">version (-)</h4> 1851 1852<p>Print the program version to standard out, optionally with licensing 1853information, then exit 0. The optional argument specifies how much licensing 1854detail to provide. The default is to print just the version. The licensing information may be selected with an option argument. 1855Only the first letter of the argument is examined: 1856</p> 1857<dl compact="compact"> 1858<dt>‘<samp>version</samp>’</dt> 1859<dd><p>Only print the version. This is the default. 1860</p></dd> 1861<dt>‘<samp>copyright</samp>’</dt> 1862<dd><p>Name the copyright usage licensing terms. 1863</p></dd> 1864<dt>‘<samp>verbose</samp>’</dt> 1865<dd><p>Print the full copyright usage licensing terms. 1866</p></dd> 1867</dl> 1868 1869<hr> 1870<span id="ntp_002dkeygen-exit-status"></span><div class="header"> 1871<p> 1872Next: <a href="#ntp_002dkeygen-Usage" accesskey="n" rel="next">ntp-keygen Usage</a>, Previous: <a href="#ntp_002dkeygen-config" accesskey="p" rel="prev">ntp-keygen config</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1873</div> 1874<span id="ntp_002dkeygen-exit-status-1"></span><h4 class="subsection">1.2.23 ntp-keygen exit status</h4> 1875 1876<p>One of the following exit values will be returned: 1877</p><dl compact="compact"> 1878<dt>‘<samp>0 (EXIT_SUCCESS)</samp>’</dt> 1879<dd><p>Successful program execution. 1880</p></dd> 1881<dt>‘<samp>1 (EXIT_FAILURE)</samp>’</dt> 1882<dd><p>The operation failed or the command syntax was not valid. 1883</p></dd> 1884<dt>‘<samp>66 (EX_NOINPUT)</samp>’</dt> 1885<dd><p>A specified configuration file could not be loaded. 1886</p></dd> 1887<dt>‘<samp>70 (EX_SOFTWARE)</samp>’</dt> 1888<dd><p>libopts had an internal operational error. Please report 1889it to autogen-users@lists.sourceforge.net. Thank you. 1890</p></dd> 1891</dl> 1892<hr> 1893<span id="ntp_002dkeygen-Usage"></span><div class="header"> 1894<p> 1895Next: <a href="#ntp_002dkeygen-Notes" accesskey="n" rel="next">ntp-keygen Notes</a>, Previous: <a href="#ntp_002dkeygen-exit-status" accesskey="p" rel="prev">ntp-keygen exit status</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1896</div> 1897<span id="ntp_002dkeygen-Usage-1"></span><h4 class="subsection">1.2.24 ntp-keygen Usage</h4> 1898<hr> 1899<span id="ntp_002dkeygen-Notes"></span><div class="header"> 1900<p> 1901Next: <a href="#ntp_002dkeygen-Bugs" accesskey="n" rel="next">ntp-keygen Bugs</a>, Previous: <a href="#ntp_002dkeygen-Usage" accesskey="p" rel="prev">ntp-keygen Usage</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1902</div> 1903<span id="ntp_002dkeygen-Notes-1"></span><h4 class="subsection">1.2.25 ntp-keygen Notes</h4> 1904<hr> 1905<span id="ntp_002dkeygen-Bugs"></span><div class="header"> 1906<p> 1907Previous: <a href="#ntp_002dkeygen-Notes" accesskey="p" rel="prev">ntp-keygen Notes</a>, Up: <a href="#ntp_002dkeygen-Invocation" accesskey="u" rel="up">ntp-keygen Invocation</a> </p> 1908</div> 1909<span id="ntp_002dkeygen-Bugs-1"></span><h4 class="subsection">1.2.26 ntp-keygen Bugs</h4> 1910 1911<hr> 1912<span id="Random-Seed-File"></span><div class="header"> 1913<p> 1914Next: <a href="#Cryptographic-Data-Files" accesskey="n" rel="next">Cryptographic Data Files</a>, Previous: <a href="#Running-the-Program" accesskey="p" rel="prev">Running the Program</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p> 1915</div> 1916<span id="Random-Seed-File-2"></span><h3 class="section">1.3 Random Seed File</h3> 1917 1918<p>All cryptographically sound key generation schemes must have means to 1919randomize the entropy seed used to initialize the internal 1920pseudo-random number generator used by the OpenSSL library routines. 1921If a site supports ssh, it is very likely that means to do this are 1922already available. 1923The entropy seed used by the OpenSSL library is contained in a file, 1924usually called <code>.rnd</code>, which must be available when 1925starting the <code>ntp-keygen</code> program or <code>ntpd</code> daemon. 1926</p> 1927<p>The OpenSSL library looks for the file using the path specified by the 1928<code>RANDFILE</code> environment variable in the user home directory, whether root 1929or some other user. 1930If the <code>RANDFILE</code> environment variable is not 1931present, the library looks for the <code>.rnd</code> file in the user home 1932directory. 1933Since both the <code>ntp-keygen</code> program and <code>ntpd</code> daemon must run 1934as root, the logical place to put this file is in <code>/.rnd</code> or 1935<code>/root/.rnd</code>. 1936If the file is not available or cannot be written, the program exits 1937with a message to the system log. 1938</p> 1939<hr> 1940<span id="Cryptographic-Data-Files"></span><div class="header"> 1941<p> 1942Previous: <a href="#Random-Seed-File" accesskey="p" rel="prev">Random Seed File</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> </p> 1943</div> 1944<span id="Cryptographic-Data-Files-2"></span><h3 class="section">1.4 Cryptographic Data Files</h3> 1945 1946<p>File and link names are in the <code>form ntpkey_key_name.fstamp</code>, 1947where <code>key</code> is the key or parameter type, 1948<code>name</code> is the host or group name and 1949<code>fstamp</code> is the filestamp (NTP seconds) when the file was created). 1950By convention, key names in generated file names include both upper and 1951lower case characters, while key names in generated link names include 1952only lower case characters. The filestamp is not used in generated link 1953names. 1954</p> 1955<p>The key name is a string defining the cryptographic key type. 1956Key types include public/private keys host and sign, certificate cert 1957and several challenge/response key types. 1958By convention, client files used for 1959challenges have a par subtype, as in the IFF challenge IFFpar, while 1960server files for responses have a key subtype, as in the GQ response 1961GQkey. 1962</p> 1963<p>All files begin with two nonencrypted lines. The first line contains 1964the file name in the format <code>ntpkey_key_host.fstamp</code>. 1965The second line contains the datestamp in conventional Unix date format. 1966Lines beginning with <code>#</code> are ignored. 1967</p> 1968<p>The remainder of the file contains cryptographic data encoded first 1969using ASN.1 rules, then encrypted using the DES-CBC algorithm with 1970given password and finally written in PEM-encoded printable ASCII text 1971preceded and followed by MIME content identifier lines. 1972</p> 1973<p>The format of the symmetric keys file, ordinarily named <code>ntp.keys</code>, 1974is somewhat different than the other files in the interest of backward 1975compatibility. 1976Ordinarily, the file is generated by this program, but 1977it can be constructed and edited using an ordinary text editor. 1978</p> 1979<div class="example"> 1980<pre class="example"># ntpkey_MD5key_hms.local.3564038757 1981# Sun Dec 9 02:45:57 2012 1982 1983 1 MD5 "]!ghT%O;3)WJ,/Nc:>I # MD5 key 1984 2 MD5 lu+H^tF46BKR-6~pV_5 # MD5 key 1985 3 MD5 :lnoVsE%Yz*avh%EtNC # MD5 key 1986 4 MD5 |fdZrf0sF~;w-i^V # MD5 key 1987 5 MD5 IyAG>O"y"LmCRS!*bHC # MD5 key 1988 6 MD5 ">e\A>hT/661ri52,,H # MD5 key 1989 7 MD5 c9x=M'CfLxax9v)PV-si # MD5 key 1990 8 MD5 E|=jvFVov?Bn|Ev=&aK\ # MD5 key 1991 9 MD5 T!c4UT&`(m$+m+B6,`Q0 # MD5 key 199210 MD5 JVF/1=)=IFbHbJQz..Cd # MD5 key 199311 SHA1 6dea311109529e436c2b4fccae9bc753c16d1b48 # SHA1 key 199412 SHA1 7076f373d86c4848c59ff8046e49cb7d614ec394 # SHA1 key 199513 SHA1 5f48b1b60591eb01b7cf1d33b7774f08d20262d3 # SHA1 key 199614 SHA1 eed5ab9d9497319ec60cf3781d52607e76720178 # SHA1 key 199715 SHA1 f283562611a04c964da8126296f5f8e58c3f85de # SHA1 key 199816 SHA1 1930da171297dd63549af50b29449de17dcf341f # SHA1 key 199917 SHA1 fee892110358cd4382322b889869e750db8e8a8f # SHA1 key 200018 SHA1 b5520c9fadd7ad3fd8bfa061c8821b65d029bb37 # SHA1 key 200119 SHA1 8c74fb440ec80f453ec6aaa62b9baed0ab723b92 # SHA1 key 200220 SHA1 6bc05f734306a189326000970c19b3910f403795 # SHA1 key 2003</pre></div> 2004 2005<p>Figure 1. Typical Symmetric Key File 2006</p> 2007<p>Figure 1 shows a typical symmetric keys file used by the reference 2008implementation. 2009Each line of the file contains three fields, first an 2010integer between 1 and 65535, inclusive, representing the key identifier 2011used in the server and peer configuration commands. 2012Next is the key type for the message digest algorithm, 2013which in the absence of the 2014OpenSSL library must be MD5 to designate the MD5 message digest 2015algorithm. 2016If the OpenSSL library is installed, the key type can be any 2017message digest algorithm supported by that library. 2018However, if 2019compatibility with FIPS 140-2 is required, the key type must be either 2020SHA or SHA1. 2021The key type can be changed using an ASCII text editor. 2022</p> 2023<p>An MD5 key consists of a printable ASCII string less than or equal to 202416 characters and terminated by whitespace or a # character. 2025An OpenSSL 2026key consists of a hex-encoded ASCII string of 40 characters, which is 2027truncated as necessary. 2028</p> 2029<p>Note that the keys used by the <code>ntpq</code> and <code>ntpdc</code> programs are 2030checked against passwords requested by the programs and entered by hand, 2031so it 2032is generally appropriate to specify these keys in human readable ASCII 2033format. 2034</p> 2035<p>The <code>ntp-keygen</code> program generates a MD5 symmetric keys file 2036<code>ntpkey_MD5key_hostname.filestamp</code>. 2037Since the file contains private 2038shared keys, it should be visible only to root and distributed by 2039secure means to other subnet hosts. 2040The NTP daemon loads the file <code>ntp.keys</code>, so <code>ntp-keygen</code> 2041installs a soft link from this name to the generated file. 2042Subsequently, similar soft links must be installed by 2043manual or automated means on the other subnet hosts. 2044While this file is 2045not used with the Autokey Version 2 protocol, it is needed to 2046authenticate some remote configuration commands used by the <code>ntpq</code> and 2047<code>ntpdc</code> utilities. 2048</p><hr> 2049 2050 2051 2052</body> 2053</html> 2054