source: chapter06/shadow.xml@ 91f0d5b

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Last change on this file since 91f0d5b was 91f0d5b, checked in by Pierre Labastie <pieere@…>, 3 years ago

Fix the rendering of an xref to man pages on the shadow page

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11484 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

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File size: 21.4 KB
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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
8<sect1 id="ch-system-shadow" role="wrap">
9 <?dbhtml filename="shadow.html"?>
10
11 <sect1info condition="script">
12 <productname>shadow</productname>
13 <productnumber>&shadow-version;</productnumber>
14 <address>&shadow-url;</address>
15 </sect1info>
16
17 <title>Shadow-&shadow-version;</title>
18
19 <indexterm zone="ch-system-shadow">
20 <primary sortas="a-Shadow">Shadow</primary>
21 </indexterm>
22
23 <sect2 role="package">
24 <title/>
25
26 <para>The Shadow package contains programs for handling passwords in a secure
27 way.</para>
28
29 <segmentedlist>
30 <segtitle>&buildtime;</segtitle>
31 <segtitle>&diskspace;</segtitle>
32
33 <seglistitem>
34 <seg>&shadow-ch6-sbu;</seg>
35 <seg>&shadow-ch6-du;</seg>
36 </seglistitem>
37 </segmentedlist>
38
39 </sect2>
40
41 <sect2 role="installation">
42 <title>Installation of Shadow</title>
43
44 <note>
45 <para>If you would like to enforce the use of strong passwords, refer to
46 <ulink url="&blfs-book;postlfs/cracklib.html"/> for installing
47 CrackLib prior to building Shadow. Then add
48 <parameter>--with-libcrack</parameter> to the <command>configure</command>
49 command below.</para>
50 </note>
51
52 <para>Disable the installation of the <command>groups</command> program
53 and its man pages, as Coreutils provides a better version. Also
54 Prevent the installation of manual pages that were already installed in
55 <xref linkend="ch-system-man-pages"/>:</para>
56
57<screen><userinput remap="pre">sed -i 's/groups$(EXEEXT) //' src/Makefile.in
58find man -name Makefile.in -exec sed -i 's/groups\.1 / /' {} \;
59find man -name Makefile.in -exec sed -i 's/getspnam\.3 / /' {} \;
60find man -name Makefile.in -exec sed -i 's/passwd\.5 / /' {} \;</userinput></screen>
61
62 <para id="shadow-login_defs">Instead of using the default
63 <emphasis>crypt</emphasis> method, use the more secure
64 <emphasis>SHA-512</emphasis> method of password encryption, which also
65 allows passwords longer than 8 characters. It is also necessary to change
66 the obsolete <filename class="directory">/var/spool/mail</filename> location
67 for user mailboxes that Shadow uses by default to the <filename
68 class="directory">/var/mail</filename> location used currently:</para>
69
70<screen><userinput remap="pre">sed -i -e 's@#ENCRYPT_METHOD DES@ENCRYPT_METHOD SHA512@' \
71 -e 's@/var/spool/mail@/var/mail@' etc/login.defs</userinput></screen>
72
73 <note>
74 <para>If you chose to build Shadow with Cracklib support, run the following:</para>
75
76<screen role="nodump"><userinput>sed -i 's@DICTPATH.*@DICTPATH\t/lib/cracklib/pw_dict@' etc/login.defs</userinput></screen>
77 </note>
78
79 <para>Make a minor change to make the first group number generated
80 by useradd 1000:</para>
81
82<screen><userinput remap="pre">sed -i 's/1000/999/' etc/useradd</userinput></screen>
83
84 <para>Prepare Shadow for compilation:</para>
85
86<screen><userinput remap="configure">./configure --sysconfdir=/etc --with-group-name-max-length=32</userinput></screen>
87
88 <variablelist>
89 <title>The meaning of the configure option:</title>
90
91 <varlistentry>
92 <term><parameter>--with-group-name-max-length=32</parameter></term>
93 <listitem>
94 <para>The maximum user name is 32 characters. Make the maximum
95 group name the same.</para>
96 </listitem>
97 </varlistentry>
98
99 </variablelist>
100
101 <para>Compile the package:</para>
102
103<screen><userinput remap="make">make</userinput></screen>
104
105 <para>This package does not come with a test suite.</para>
106
107 <para>Install the package:</para>
108
109<screen><userinput remap="install">make install</userinput></screen>
110
111 <para>Move a misplaced program to its proper location:</para>
112
113<screen><userinput remap="install">mv -v /usr/bin/passwd /bin</userinput></screen>
114
115 <!-- <para>Move Shadow's libraries to more appropriate locations:</para>
116
117<screen><userinput remap="install">mv -v /lib/libshadow.*a /usr/lib
118rm -v /lib/libshadow.so
119ln -sfv ../../lib/libshadow.so.0 /usr/lib/libshadow.so</userinput></screen> -->
120
121 </sect2>
122
123 <sect2 id="conf-shadow" role="configuration">
124 <title>Configuring Shadow</title>
125
126 <indexterm zone="conf-shadow">
127 <primary sortas="a-Shadow">Shadow</primary>
128 <secondary>configuring</secondary>
129 </indexterm>
130
131 <para>This package contains utilities to add, modify, and delete users and
132 groups; set and change their passwords; and perform other administrative
133 tasks. For a full explanation of what <emphasis>password shadowing</emphasis>
134 means, see the <filename>doc/HOWTO</filename> file within the unpacked
135 source tree. If using Shadow support, keep in mind that programs which need
136 to verify passwords (display managers, FTP programs, pop3 daemons, etc.)
137 must be Shadow-compliant. That is, they need to be able to work with
138 shadowed passwords.</para>
139
140 <para>To enable shadowed passwords, run the following command:</para>
141
142<screen><userinput>pwconv</userinput></screen>
143
144 <para>To enable shadowed group passwords, run:</para>
145
146<screen><userinput>grpconv</userinput></screen>
147
148 <para>Shadow's stock configuration for the <command>useradd</command>
149 utility has a few caveats that need some explanation. First, the default
150 action for the <command>useradd</command> utility is to create the user and
151 a group of the same name as the user. By default the user ID (UID) and
152 group ID (GID) numbers will begin with 1000. This means if you don't pass
153 parameters to <command>useradd</command>, each user will be a member of a
154 unique group on the system. If this behavior is undesirable, you'll need
155 to pass the <parameter>-g</parameter> parameter to
156 <command>useradd</command>. The default parameters are stored in the
157 <filename>/etc/default/useradd</filename> file. You may need to modify two
158 parameters in this file to suit your particular needs.</para>
159
160 <variablelist>
161 <title><filename>/etc/default/useradd</filename> Parameter Explanations</title>
162
163 <varlistentry>
164 <term><parameter>GROUP=1000</parameter></term>
165 <listitem>
166 <para>This parameter sets the beginning of the group numbers used in
167 the /etc/group file. You can modify it to anything you desire. Note
168 that <command>useradd</command> will never reuse a UID or GID. If the
169 number identified in this parameter is used, it will use the next
170 available number after this. Note also that if you don't have a group
171 1000 on your system the first time you use <command>useradd</command>
172 without the <parameter>-g</parameter> parameter, you'll get a message
173 displayed on the terminal that says:
174 <computeroutput>useradd: unknown GID 1000</computeroutput>. You may
175 disregard this message and group number 1000 will be used.</para>
176 </listitem>
177 </varlistentry>
178 <varlistentry>
179 <term><parameter>CREATE_MAIL_SPOOL=yes</parameter></term>
180 <listitem>
181 <para>This parameter causes <command>useradd</command> to create a
182 mailbox file for the newly created user. <command>useradd</command>
183 will make the group ownership of this file to the
184 <systemitem class="groupname">mail</systemitem> group with 0660
185 permissions. If you would prefer that these mailbox files are not
186 created by <command>useradd</command>, issue the following
187 command:</para>
188
189<screen><userinput>sed -i 's/yes/no/' /etc/default/useradd</userinput></screen>
190 </listitem>
191 </varlistentry>
192
193 </variablelist>
194
195
196 </sect2>
197
198 <sect2 role="configuration">
199 <title>Setting the root password</title>
200
201 <para>Choose a password for user <emphasis>root</emphasis> and set it
202 by running:</para>
203
204<screen role="nodump"><userinput>passwd root</userinput></screen>
205
206 </sect2>
207
208 <sect2 id="contents-shadow" role="content">
209 <title>Contents of Shadow</title>
210
211 <segmentedlist>
212 <segtitle>Installed programs</segtitle>
213 <segtitle>Installed directory</segtitle>
214
215 <seglistitem>
216 <seg>chage, chfn, chgpasswd, chpasswd, chsh, expiry, faillog, gpasswd,
217 groupadd, groupdel, groupmems, groupmod, grpck, grpconv, grpunconv,
218 lastlog, login, logoutd, newgidmap, newgrp, newuidmap, newusers,
219 nologin, passwd, pwck, pwconv, pwunconv, sg (link to newgrp), su,
220 useradd, userdel, usermod, vigr (link to vipw), and vipw</seg>
221 <seg>/etc/default</seg>
222 </seglistitem>
223 </segmentedlist>
224
225 <variablelist>
226 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
227 <?dbfo list-presentation="list"?>
228 <?dbhtml list-presentation="table"?>
229
230 <varlistentry id="chage">
231 <term><command>chage</command></term>
232 <listitem>
233 <para>Used to change the maximum number of days between obligatory
234 password changes</para>
235 <indexterm zone="ch-system-shadow chage">
236 <primary sortas="b-chage">chage</primary>
237 </indexterm>
238 </listitem>
239 </varlistentry>
240
241 <varlistentry id="chfn">
242 <term><command>chfn</command></term>
243 <listitem>
244 <para>Used to change a user's full name and other information</para>
245 <indexterm zone="ch-system-shadow chfn">
246 <primary sortas="b-chfn">chfn</primary>
247 </indexterm>
248 </listitem>
249 </varlistentry>
250
251 <varlistentry id="chgpasswd">
252 <term><command>chgpasswd</command></term>
253 <listitem>
254 <para>Used to update group passwords in batch mode</para>
255 <indexterm zone="ch-system-shadow chgpasswd">
256 <primary sortas="b-chgpasswd">chgpasswd</primary>
257 </indexterm>
258 </listitem>
259 </varlistentry>
260
261 <varlistentry id="chpasswd">
262 <term><command>chpasswd</command></term>
263 <listitem>
264 <para>Used to update user passwords in batch mode</para>
265 <indexterm zone="ch-system-shadow chpasswd">
266 <primary sortas="b-chpasswd">chpasswd</primary>
267 </indexterm>
268 </listitem>
269 </varlistentry>
270
271 <varlistentry id="chsh">
272 <term><command>chsh</command></term>
273 <listitem>
274 <para>Used to change a user's default login shell</para>
275 <indexterm zone="ch-system-shadow chsh">
276 <primary sortas="b-chsh">chsh</primary>
277 </indexterm>
278 </listitem>
279 </varlistentry>
280
281 <varlistentry id="expiry">
282 <term><command>expiry</command></term>
283 <listitem>
284 <para>Checks and enforces the current password expiration policy</para>
285 <indexterm zone="ch-system-shadow expiry">
286 <primary sortas="b-expiry">expiry</primary>
287 </indexterm>
288 </listitem>
289 </varlistentry>
290
291 <varlistentry id="faillog">
292 <term><command>faillog</command></term>
293 <listitem>
294 <para>Is used to examine the log of login failures, to set a maximum
295 number of failures before an account is blocked, or to reset the
296 failure count</para>
297 <indexterm zone="ch-system-shadow faillog">
298 <primary sortas="b-faillog">faillog</primary>
299 </indexterm>
300 </listitem>
301 </varlistentry>
302
303 <varlistentry id="gpasswd">
304 <term><command>gpasswd</command></term>
305 <listitem>
306 <para>Is used to add and delete members and administrators to
307 groups</para>
308 <indexterm zone="ch-system-shadow gpasswd">
309 <primary sortas="b-gpasswd">gpasswd</primary>
310 </indexterm>
311 </listitem>
312 </varlistentry>
313
314 <varlistentry id="groupadd">
315 <term><command>groupadd</command></term>
316 <listitem>
317 <para>Creates a group with the given name</para>
318 <indexterm zone="ch-system-shadow groupadd">
319 <primary sortas="b-groupadd">groupadd</primary>
320 </indexterm>
321 </listitem>
322 </varlistentry>
323
324 <varlistentry id="groupdel">
325 <term><command>groupdel</command></term>
326 <listitem>
327 <para>Deletes the group with the given name</para>
328 <indexterm zone="ch-system-shadow groupdel">
329 <primary sortas="b-groupdel">groupdel</primary>
330 </indexterm>
331 </listitem>
332 </varlistentry>
333
334 <varlistentry id="groupmems">
335 <term><command>groupmems</command></term>
336 <listitem>
337 <para>Allows a user to administer his/her own group membership list
338 without the requirement of super user privileges.</para>
339 <indexterm zone="ch-system-shadow groupmems">
340 <primary sortas="b-groupmems">groupmems</primary>
341 </indexterm>
342 </listitem>
343 </varlistentry>
344
345 <varlistentry id="groupmod">
346 <term><command>groupmod</command></term>
347 <listitem>
348 <para>Is used to modify the given group's name or GID</para>
349 <indexterm zone="ch-system-shadow groupmod">
350 <primary sortas="b-groupmod">groupmod</primary>
351 </indexterm>
352 </listitem>
353 </varlistentry>
354
355 <varlistentry id="grpck">
356 <term><command>grpck</command></term>
357 <listitem>
358 <para>Verifies the integrity of the group files
359 <filename>/etc/group</filename> and
360 <filename>/etc/gshadow</filename></para>
361 <indexterm zone="ch-system-shadow grpck">
362 <primary sortas="b-grpck">grpck</primary>
363 </indexterm>
364 </listitem>
365 </varlistentry>
366
367 <varlistentry id="grpconv">
368 <term><command>grpconv</command></term>
369 <listitem>
370 <para>Creates or updates the shadow group file from the normal
371 group file</para>
372 <indexterm zone="ch-system-shadow grpconv">
373 <primary sortas="b-grpconv">grpconv</primary>
374 </indexterm>
375 </listitem>
376 </varlistentry>
377
378 <varlistentry id="grpunconv">
379 <term><command>grpunconv</command></term>
380 <listitem>
381 <para>Updates <filename>/etc/group</filename> from
382 <filename>/etc/gshadow</filename> and then deletes the latter</para>
383 <indexterm zone="ch-system-shadow grpunconv">
384 <primary sortas="b-grpunconv">grpunconv</primary>
385 </indexterm>
386 </listitem>
387 </varlistentry>
388
389 <varlistentry id="lastlog">
390 <term><command>lastlog</command></term>
391 <listitem>
392 <para>Reports the most recent login of all users or of a
393 given user</para>
394 <indexterm zone="ch-system-shadow lastlog">
395 <primary sortas="b-lastlog">lastlog</primary>
396 </indexterm>
397 </listitem>
398 </varlistentry>
399
400 <varlistentry id="login">
401 <term><command>login</command></term>
402 <listitem>
403 <para>Is used by the system to let users sign on</para>
404 <indexterm zone="ch-system-shadow login">
405 <primary sortas="b-login">login</primary>
406 </indexterm>
407 </listitem>
408 </varlistentry>
409
410 <varlistentry id="logoutd">
411 <term><command>logoutd</command></term>
412 <listitem>
413 <para>Is a daemon used to enforce restrictions on log-on time
414 and ports</para>
415 <indexterm zone="ch-system-shadow logoutd">
416 <primary sortas="b-logoutd">logoutd</primary>
417 </indexterm>
418 </listitem>
419 </varlistentry>
420
421 <varlistentry id="newgidmap">
422 <term><command>newgidmap</command></term>
423 <listitem>
424 <para>Is used to set the gid mapping of a user namespace</para>
425 <indexterm zone="ch-system-shadow newgidmap">
426 <primary sortas="b-newgidmap">newgidmap</primary>
427 </indexterm>
428 </listitem>
429 </varlistentry>
430
431 <varlistentry id="newgrp">
432 <term><command>newgrp</command></term>
433 <listitem>
434 <para>Is used to change the current GID during a login session</para>
435 <indexterm zone="ch-system-shadow newgrp">
436 <primary sortas="b-newgrp">newgrp</primary>
437 </indexterm>
438 </listitem>
439 </varlistentry>
440
441 <varlistentry id="newuidmap">
442 <term><command>newuidmap</command></term>
443 <listitem>
444 <para>Is used to set the uid mapping of a user namespace</para>
445 <indexterm zone="ch-system-shadow newuidmap">
446 <primary sortas="b-newuidmap">newuidmap</primary>
447 </indexterm>
448 </listitem>
449 </varlistentry>
450
451 <varlistentry id="newusers">
452 <term><command>newusers</command></term>
453 <listitem>
454 <para>Is used to create or update an entire series of user
455 accounts</para>
456 <indexterm zone="ch-system-shadow newusers">
457 <primary sortas="b-newusers">newusers</primary>
458 </indexterm>
459 </listitem>
460 </varlistentry>
461
462 <varlistentry id="nologin">
463 <term><command>nologin</command></term>
464 <listitem>
465 <para>Displays a message that an account is not available; it is designed
466 to be used as the default shell for accounts that have been
467 disabled</para>
468 <indexterm zone="ch-system-shadow nologin">
469 <primary sortas="b-nologin">nologin</primary>
470 </indexterm>
471 </listitem>
472 </varlistentry>
473
474 <varlistentry id="passwd">
475 <term><command>passwd</command></term>
476 <listitem>
477 <para>Is used to change the password for a user or group account</para>
478 <indexterm zone="ch-system-shadow passwd">
479 <primary sortas="b-passwd">passwd</primary>
480 </indexterm>
481 </listitem>
482 </varlistentry>
483
484 <varlistentry id="pwck">
485 <term><command>pwck</command></term>
486 <listitem>
487 <para>Verifies the integrity of the password files
488 <filename>/etc/passwd</filename> and
489 <filename>/etc/shadow</filename></para>
490 <indexterm zone="ch-system-shadow pwck">
491 <primary sortas="b-pwck">pwck</primary>
492 </indexterm>
493 </listitem>
494 </varlistentry>
495
496 <varlistentry id="pwconv">
497 <term><command>pwconv</command></term>
498 <listitem>
499 <para>Creates or updates the shadow password file from the normal
500 password file</para>
501 <indexterm zone="ch-system-shadow pwconv">
502 <primary sortas="b-pwconv">pwconv</primary>
503 </indexterm>
504 </listitem>
505 </varlistentry>
506
507 <varlistentry id="pwunconv">
508 <term><command>pwunconv</command></term>
509 <listitem>
510 <para>Updates <filename>/etc/passwd</filename> from
511 <filename>/etc/shadow</filename> and then deletes the latter</para>
512 <indexterm zone="ch-system-shadow pwunconv">
513 <primary sortas="b-pwunconv">pwunconv</primary>
514 </indexterm>
515 </listitem>
516 </varlistentry>
517
518 <varlistentry id="sg">
519 <term><command>sg</command></term>
520 <listitem>
521 <para>Executes a given command while the user's GID
522 is set to that of the given group</para>
523 <indexterm zone="ch-system-shadow sg">
524 <primary sortas="b-sg">sg</primary>
525 </indexterm>
526 </listitem>
527 </varlistentry>
528
529 <varlistentry id="su">
530 <term><command>su</command></term>
531 <listitem>
532 <para>Runs a shell with substitute user and group IDs</para>
533 <indexterm zone="ch-system-shadow su">
534 <primary sortas="b-su">su</primary>
535 </indexterm>
536 </listitem>
537 </varlistentry>
538
539 <varlistentry id="useradd">
540 <term><command>useradd</command></term>
541 <listitem>
542 <para>Creates a new user with the given name, or updates the default
543 new-user information</para>
544 <indexterm zone="ch-system-shadow useradd">
545 <primary sortas="b-useradd">useradd</primary>
546 </indexterm>
547 </listitem>
548 </varlistentry>
549
550 <varlistentry id="userdel">
551 <term><command>userdel</command></term>
552 <listitem>
553 <para>Deletes the given user account</para>
554 <indexterm zone="ch-system-shadow userdel">
555 <primary sortas="b-userdel">userdel</primary>
556 </indexterm>
557 </listitem>
558 </varlistentry>
559
560 <varlistentry id="usermod">
561 <term><command>usermod</command></term>
562 <listitem>
563 <para>Is used to modify the given user's login name, User
564 Identification (UID), shell, initial group, home directory, etc.</para>
565 <indexterm zone="ch-system-shadow usermod">
566 <primary sortas="b-usermod">usermod</primary>
567 </indexterm>
568 </listitem>
569 </varlistentry>
570
571 <varlistentry id="vigr">
572 <term><command>vigr</command></term>
573 <listitem>
574 <para>Edits the <filename>/etc/group</filename> or
575 <filename>/etc/gshadow</filename> files</para>
576 <indexterm zone="ch-system-shadow vigr">
577 <primary sortas="b-vigr">vigr</primary>
578 </indexterm>
579 </listitem>
580 </varlistentry>
581
582 <varlistentry id="vipw">
583 <term><command>vipw</command></term>
584 <listitem>
585 <para>Edits the <filename>/etc/passwd</filename> or
586 <filename>/etc/shadow</filename> files</para>
587 <indexterm zone="ch-system-shadow vipw">
588 <primary sortas="b-vipw">vipw</primary>
589 </indexterm>
590 </listitem>
591 </varlistentry>
592
593 </variablelist>
594
595 </sect2>
596
597</sect1>
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