source: networking/netprogs/ntp.xml@ 6c183b5

10.0 10.1 11.0 ken/refactor-virt lazarus qt5new trunk xry111/git-date xry111/git-date-for-trunk xry111/git-date-test
Last change on this file since 6c183b5 was 6c183b5, checked in by Pierre Labastie <pieere@…>, 18 months ago

Add user CFLAGS to CFLAGS=-fcommon

git-svn-id: svn://svn.linuxfromscratch.org/BLFS/trunk/BOOK@23132 af4574ff-66df-0310-9fd7-8a98e5e911e0

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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../../general.ent">
5 %general-entities;
6
7 <!ENTITY ntp-download-http "https://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-4.2/ntp-&ntp-version;.tar.gz">
8 <!ENTITY ntp-download-ftp " ">
9 <!ENTITY ntp-md5sum "783edaf1d68ddf651bde64eda54a579d">
10 <!ENTITY ntp-size "6.7 MB">
11 <!ENTITY ntp-buildsize "119 MB (with tests)">
12 <!ENTITY ntp-time "0.7 SBU (with tests)">
13]>
14
15<sect1 id="ntp" xreflabel="ntp-&ntp-version;">
16 <?dbhtml filename="ntp.html"?>
17
18 <sect1info>
19 <othername>$LastChangedBy$</othername>
20 <date>$Date$</date>
21 </sect1info>
22
23 <title>ntp-&ntp-version;</title>
24
25 <indexterm zone="ntp">
26 <primary sortas="a-ntp">ntp</primary>
27 </indexterm>
28
29 <sect2 role="package">
30 <title>Introduction to ntp</title>
31
32 <para>
33 The <application>ntp</application> package contains a client and server
34 to keep the time synchronized between various computers over
35 a network. This package is the official reference implementation of the
36 NTP protocol.
37 </para>
38
39 &lfs91_checked;
40
41 <bridgehead renderas="sect3">Package Information</bridgehead>
42 <itemizedlist spacing="compact">
43 <listitem>
44 <para>
45 Download (HTTP): <ulink url="&ntp-download-http;"/>
46 </para>
47 </listitem>
48 <listitem>
49 <para>
50 Download (FTP): <ulink url="&ntp-download-ftp;"/>
51 </para>
52 </listitem>
53 <listitem>
54 <para>
55 Download MD5 sum: &ntp-md5sum;
56 </para>
57 </listitem>
58 <listitem>
59 <para>
60 Download size: &ntp-size;
61 </para>
62 </listitem>
63 <listitem>
64 <para>
65 Estimated disk space required: &ntp-buildsize;
66 </para>
67 </listitem>
68 <listitem>
69 <para>
70 Estimated build time: &ntp-time;
71 </para>
72 </listitem>
73 </itemizedlist>
74
75 <bridgehead renderas="sect3">ntp Dependencies</bridgehead>
76
77 <bridgehead renderas="sect4">Required</bridgehead>
78 <para role="required">
79 <xref linkend="perl-io-socket-ssl"/>
80 </para>
81
82<!-- Tested 4.2.8p11 with neither wget nor lynx on system: Not required.
83 <bridgehead renderas="sect4">Recommended</bridgehead>
84 <para role="recommended">
85 <xref role="runtime" linkend="wget"/> (runtime, for
86 <command>update-leap</command>)
87<!- - The download code for update-leap uses the File::Fetch perl module,
88 which may use wget, or lynx, or some core perl modules, so maybe move
89 to optional - ->
90 </para>
91-->
92 <bridgehead renderas="sect4">Optional</bridgehead>
93 <para role="optional">
94 <xref linkend="libcap-pam"/>,
95 <xref linkend="libevent"/>,
96 <ulink url="http://www.thrysoee.dk/editline/">libedit</ulink>, and
97 <ulink url="https://www.gnu.org/software/autogen/">libopts from AutoGen</ulink>
98 </para>
99
100 <para condition="html" role="usernotes">User Notes:
101 <ulink url="&blfs-wiki;/ntp"/></para>
102
103 </sect2>
104
105 <sect2 role="installation">
106 <title>Installation of ntp</title>
107
108 <para>
109 There should be a dedicated user and group to take control
110 of the <command>ntpd</command> daemon after it is
111 started. Issue the following commands as the
112 <systemitem class="username">root</systemitem> user:
113 </para>
114
115<screen role="root"><userinput>groupadd -g 87 ntp &amp;&amp;
116useradd -c "Network Time Protocol" -d /var/lib/ntp -u 87 \
117 -g ntp -s /bin/false ntp</userinput></screen>
118
119<!-- At least one of the issues has been reported upstream. The next para
120 is valid for 4.8.2p10 -->
121 <para>
122 The <command>update-leap</command> command needs to be fixed in order
123 to run properly:
124 </para>
125
126<screen><userinput>sed -e 's/"(\\S+)"/"?([^\\s"]+)"?/' \
127 -i scripts/update-leap/update-leap.in</userinput></screen>
128
129 <para>
130 Install <application>ntp</application> by running
131 the following commands:
132 </para>
133
134<!--
135 Note: Check if -fcommon is still required on versions gtr 4.2.8p14
136 Its a "hack" for gcc-10
137-->
138<screen><userinput>./configure CFLAGS="-O2 -g -fPIC -fcommon $CFLAGS" \
139 --prefix=/usr \
140 --bindir=/usr/sbin \
141 --sysconfdir=/etc \
142 --enable-linuxcaps \
143 --with-lineeditlibs=readline \
144 --docdir=/usr/share/doc/ntp-&ntp-version; &amp;&amp;
145make</userinput></screen>
146
147 <para>
148 To test the results, issue: <command>make check</command>.
149 </para>
150
151 <para>
152 Now, as the <systemitem class="username">root</systemitem> user:
153 </para>
154
155<screen role="root"><userinput>make install &amp;&amp;
156install -v -o ntp -g ntp -d /var/lib/ntp</userinput></screen>
157
158 </sect2>
159
160 <sect2 role="commands">
161 <title>Command Explanations</title>
162
163 <para>
164 <envar>CFLAGS="-O2 -g -fPIC"</envar>: This environment variable
165 is necessary to generate Position Independent Code needed for
166 use in the package libraries.
167 </para>
168
169 <para>
170 <parameter>--bindir=/usr/sbin</parameter>: This parameter places
171 the administrative programs in <filename
172 class="directory">/usr/sbin</filename>.
173 </para>
174
175 <para>
176 <parameter>--enable-linuxcaps</parameter>: ntpd is run as user
177 ntp, so use Linux capabilities for non-root clock control.
178 </para>
179
180 <para>
181 <parameter>--with-lineeditlibs=readline</parameter>: This switch
182 enables <application>Readline</application> support for
183 <command>ntpdc</command> and <command>ntpq</command> programs. If omitted,
184 <application>libedit</application> will be used if installed, otherwise no
185 readline capabilites will be compiled.
186 </para>
187
188 </sect2>
189
190 <sect2 role="configuration">
191 <title>Configuring ntp</title>
192
193 <sect3 id="ntp-config">
194 <title>Config Files</title>
195
196 <para>
197 <filename>/etc/ntp.conf</filename>
198 </para>
199
200 <indexterm zone="ntp ntp-config">
201 <primary sortas="e-etc-ntp.conf">/etc/ntp.conf</primary>
202 </indexterm>
203
204 </sect3>
205
206 <sect3>
207 <title>Configuration Information</title>
208
209 <para>
210 The following configuration file first defines various ntp
211 servers with open access from different continents. Second, it
212 creates a drift file where <command>ntpd</command> stores the
213 frequency offset and a pid file to store the
214 <command>ntpd</command> process ID. Third, it defines the location
215 for the leap-second definition file
216 <filename>/etc/ntp.leapseconds</filename>, that the
217 <command>update-leap</command> script checks and updates, when
218 necessary. This script can be run as a cron job and the
219 <application>ntp</application> developers recommend a frequency of
220 about three weeks for the updates. Since the documentation included
221 with the package is sparse, visit the ntp website at
222 <ulink url="http://www.ntp.org/"/> and
223 <ulink url="http://www.pool.ntp.org/"/> for more information.
224 </para>
225
226<screen role="root"><userinput>cat &gt; /etc/ntp.conf &lt;&lt; "EOF"
227<literal># Asia
228server 0.asia.pool.ntp.org
229
230# Australia
231server 0.oceania.pool.ntp.org
232
233# Europe
234server 0.europe.pool.ntp.org
235
236# North America
237server 0.north-america.pool.ntp.org
238
239# South America
240server 2.south-america.pool.ntp.org
241
242driftfile /var/lib/ntp/ntp.drift
243pidfile /var/run/ntpd.pid
244
245leapfile /var/lib/ntp/ntp.leapseconds</literal>
246EOF</userinput></screen>
247
248 <para>
249 You may wish to add a <quote>Security session</quote>. For
250 explanations, see <ulink url=
251 "https://www.eecis.udel.edu/~mills/ntp/html/accopt.html#restrict"/>.
252 </para>
253
254<screen role="root"><userinput>cat &gt;&gt; /etc/ntp.conf &lt;&lt; "EOF"
255<literal># Security session
256restrict default limited kod nomodify notrap nopeer noquery
257restrict -6 default limited kod nomodify notrap nopeer noquery
258
259restrict 127.0.0.1
260restrict ::1</literal>
261EOF</userinput></screen>
262
263 </sect3>
264
265 <sect3 id="ntp-init">
266 <title>Synchronizing the Time</title>
267
268 <para>
269 There are two options. Option one is to run <command>ntpd</command>
270 continuously and allow it to synchronize the time in a gradual manner.
271 The other option is to run <command>ntpd</command> periodically (using
272 cron) and update the time each time <command>ntpd</command> is
273 scheduled.
274 </para>
275
276 <para>
277 If you choose Option one, then install the
278 <phrase revision="sysv"><filename>/etc/rc.d/init.d/ntp</filename>
279 init script</phrase>
280 <phrase revision="systemd"><filename>ntpd.service</filename>
281 unit</phrase>
282 included in the
283 <xref linkend="bootscripts" revision="sysv"/>
284 <xref linkend="systemd-units" revision="systemd"/> package.
285 </para>
286
287 <indexterm zone="ntp ntp-init" revision="sysv">
288 <primary sortas="f-ntp">ntp</primary>
289 </indexterm>
290
291 <indexterm zone="ntp ntp-init" revision="systemd">
292 <primary sortas="f-ntpd">ntpd.service</primary>
293 </indexterm>
294
295<screen role="root"><userinput>make install-ntpd</userinput></screen>
296
297 <para>
298 If you prefer to run <command>ntpd</command> periodically, add the
299 following command to <systemitem class="username">root</systemitem>'s
300 <filename>crontab</filename>:
301 </para>
302
303<screen><literal>ntpd -q</literal></screen>
304
305 <para revision="sysv">
306 Execute the following command if you would like to set the hardware
307 clock to the current system time at shutdown and reboot:
308 </para>
309
310<screen role="root" revision="sysv"><userinput>ln -v -sf ../init.d/setclock /etc/rc.d/rc0.d/K46setclock &amp;&amp;
311ln -v -sf ../init.d/setclock /etc/rc.d/rc6.d/K46setclock</userinput></screen>
312
313 <para revision="sysv">
314 The other way around is already set up by LFS.
315 </para>
316
317 </sect3>
318
319 </sect2>
320
321 <sect2 role="content">
322 <title>Contents</title>
323
324 <segmentedlist>
325 <segtitle>Installed Programs</segtitle>
326 <segtitle>Installed Libraries</segtitle>
327 <segtitle>Installed Directories</segtitle>
328
329 <seglistitem>
330 <seg>calc_tickadj, ntp-keygen, ntp-wait, ntpd, ntpdate, ntpdc, ntpq,
331 ntptime, ntptrace, sntp, tickadj and update-leap</seg>
332 <seg>None</seg>
333 <seg>/usr/share/ntp,
334 /usr/share/doc/ntp-4.2.8 and
335 /var/lib/ntp</seg>
336 </seglistitem>
337 </segmentedlist>
338
339 <variablelist>
340 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
341 <?dbfo list-presentation="list"?>
342 <?dbhtml list-presentation="table"?>
343
344 <varlistentry id="calc_tickadj">
345 <term><command>calc_tickadj</command></term>
346 <listitem>
347 <para>
348 calculates optimal value for tick given ntp drift file.
349 </para>
350 <indexterm zone="ntp calc_tickadj">
351 <primary sortas="b-calc_tickadj">calc_tickadj</primary>
352 </indexterm>
353 </listitem>
354 </varlistentry>
355
356 <varlistentry id="ntp-keygen">
357 <term><command>ntp-keygen</command></term>
358 <listitem>
359 <para>
360 generates cryptographic data files used by the NTPv4 authentication
361 and identification schemes.
362 </para>
363 <indexterm zone="ntp ntp-keygen">
364 <primary sortas="b-ntp-keygen">ntp-keygen</primary>
365 </indexterm>
366 </listitem>
367 </varlistentry>
368
369 <varlistentry id="ntp-wait">
370 <term><command>ntp-wait</command></term>
371 <listitem>
372 <para>
373 is useful at boot time, to delay the boot sequence until
374 <command>ntpd</command> has set the time.
375 </para>
376 <indexterm zone="ntp ntp-wait">
377 <primary sortas="b-ntp-wait">ntp-wait</primary>
378 </indexterm>
379 </listitem>
380 </varlistentry>
381
382 <varlistentry id="ntpd">
383 <term><command>ntpd</command></term>
384 <listitem>
385 <para>
386 is a ntp daemon that runs in the background and keeps
387 the date and time synchronized based on response from configured
388 ntp servers. It also functions as a ntp server.
389 </para>
390 <indexterm zone="ntp ntpd">
391 <primary sortas="b-ntpd">ntpd</primary>
392 </indexterm>
393 </listitem>
394 </varlistentry>
395
396 <varlistentry id="ntpdate">
397 <term><command>ntpdate</command></term>
398 <listitem>
399 <para>
400 is a client program that sets the date and time based on
401 the response from an ntp server. This command is deprecated.
402 </para>
403 <indexterm zone="ntp ntpdate">
404 <primary sortas="b-ntpdate">ntpdate</primary>
405 </indexterm>
406 </listitem>
407 </varlistentry>
408
409 <varlistentry id="ntpdc">
410 <term><command>ntpdc</command></term>
411 <listitem>
412 <para>
413 is used to query the ntp daemon about its current state
414 and to request changes in that state.
415 </para>
416 <indexterm zone="ntp ntpdc">
417 <primary sortas="b-ntpdc">ntpdc</primary>
418 </indexterm>
419 </listitem>
420 </varlistentry>
421
422 <varlistentry id="ntpq">
423 <term><command>ntpq</command></term>
424 <listitem>
425 <para>
426 is a utility program used to monitor <command>ntpd</command>
427 operations and determine performance.
428 </para>
429 <indexterm zone="ntp ntpq">
430 <primary sortas="b-ntpq">ntpq</primary>
431 </indexterm>
432 </listitem>
433 </varlistentry>
434
435 <varlistentry id="ntptime">
436 <term><command>ntptime</command></term>
437 <listitem>
438 <para>
439 reads and displays time-related kernel variables.
440 </para>
441 <indexterm zone="ntp ntptime">
442 <primary sortas="b-ntptime">ntptime</primary>
443 </indexterm>
444 </listitem>
445 </varlistentry>
446
447 <varlistentry id="ntptrace">
448 <term><command>ntptrace</command></term>
449 <listitem>
450 <para>
451 traces a chain of ntp servers back to the primary source.
452 </para>
453 <indexterm zone="ntp ntptrace">
454 <primary sortas="b-ntptrace">ntptrace</primary>
455 </indexterm>
456 </listitem>
457 </varlistentry>
458
459 <varlistentry id="sntp">
460 <term><command>sntp</command></term>
461 <listitem>
462 <para>
463 is a Simple Network Time Protocol (SNTP) client.
464 </para>
465 <indexterm zone="ntp sntp">
466 <primary sortas="b-sntp">sntp</primary>
467 </indexterm>
468 </listitem>
469 </varlistentry>
470
471 <varlistentry id="tickadj">
472 <term><command>tickadj</command></term>
473 <listitem>
474 <para>
475 reads, and optionally modifies, several timekeeping-related
476 variables in older kernels that do not have support for precision
477 timekeeping.
478 </para>
479 <indexterm zone="ntp tickadj">
480 <primary sortas="b-tickadj">tickadj</primary>
481 </indexterm>
482 </listitem>
483 </varlistentry>
484
485 <varlistentry id="update-leap">
486 <term><command>update-leap</command></term>
487 <listitem>
488 <para>
489 is a script to verify and, if necessary, update the leap-second
490 definition file.
491 </para>
492 <indexterm zone="ntp update-leap">
493 <primary sortas="b-update-leap">update-leap</primary>
494 </indexterm>
495 </listitem>
496 </varlistentry>
497
498 </variablelist>
499
500 </sect2>
501
502</sect1>
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