1LOGIN.DEFS(5) File Formats and Configuration LOGIN.DEFS(5)
2
6 login.defs - shadow password suite configuration
7
9 The /etc/login.defs file defines the site-specific configuration for
10 the shadow password suite. This file is required. Absence of this file
11 will not prevent system operation, but will probably result in
12 undesirable operation.
13 This file is a readable text file, each line of the file describing one
15 configuration parameter. The lines consist of a configuration name and
16 value, separated by whitespace. Blank lines and comment lines are
17 ignored. Comments are introduced with a "#" pound sign and the pound
18 sign must be the first non-white character of the line.
19 Parameter values may be of four types: strings, booleans, numbers, and
21 long numbers. A string is comprised of any printable characters. A
22 boolean should be either the value yes or no. An undefined boolean
23 parameter or one with a value other than these will be given a no
24 value. Numbers (both regular and long) may be either decimal values,
25 octal values (precede the value with 0) or hexadecimal values (precede
26 the value with 0x). The maximum value of the regular and long numeric
27 parameters is machine-dependent.
28 Please note that the parameters in this configuration file control the
30 behavior of the tools from the shadow-utils component. None of these
31 tools uses the PAM mechanism, and the utilities that use PAM (such as
32 the passwd command) should be configured elsewhere. The only values
33 that affect PAM modules are ENCRYPT_METHOD and SHA_CRYPT_MAX_ROUNDS for
34 pam_unix module, FAIL_DELAY for pam_faildelay module, and UMASK for
35 pam_umask module. Refer to pam(8) for more information.
36 The following configuration items are provided:
38 CHFN_AUTH (boolean)
40 If yes, the chfn program will require authentication before making
41 any changes, unless run by the superuser.
42 CHFN_RESTRICT (string)
44 This parameter specifies which values in the gecos field of the
45 /etc/passwd file may be changed by regular users using the chfn
46 program. It can be any combination of letters f, r, w, h, for Full
47 name, Room number, Work phone, and Home phone, respectively. For
48 backward compatibility, yes is equivalent to rwh and no is
49 equivalent to frwh. If not specified, only the superuser can make
50 any changes. The most restrictive setting is better achieved by not
51 installing chfn SUID.
52 CHSH_AUTH (boolean)
54 If yes, the chsh program will require authentication before making
55 any changes, unless run by the superuser.
56 CONSOLE (string)
58 If defined, either full pathname of a file containing device names
59 (one per line) or a ":" delimited list of device names. Root logins
60 will be allowed only upon these devices.
61 If not defined, root will be allowed on any device.
63 The device should be specified without the /dev/ prefix.
65 CONSOLE_GROUPS (string)
67 List of groups to add to the user's supplementary groups set when
68 logging in on the console (as determined by the CONSOLE setting).
69 Default is none.
70 Use with caution - it is possible for users to gain permanent
72 access to these groups, even when not logged in on the console.
73 CREATE_HOME (boolean)
75 Indicate if a home directory should be created by default for new
76 users.
77 This setting does not apply to system users, and can be overridden
79 on the command line.
80 DEFAULT_HOME (boolean)
82 Indicate if login is allowed if we can't cd to the home directory.
83 Default is no.
84 If set to yes, the user will login in the root (/) directory if it
86 is not possible to cd to her home directory.
87 ENCRYPT_METHOD (string)
89 This defines the system default encryption algorithm for encrypting
90 passwords (if no algorithm are specified on the command line).
91 It can take one of these values: DES (default), MD5, SHA256,
93 SHA512. MD5 and DES should not be used for new hashes, see crypt(5)
94 for recommendations.
95 Note: this parameter overrides the MD5_CRYPT_ENAB variable.
97 ENV_HZ (string)
99 If set, it will be used to define the HZ environment variable when
100 a user login. The value must be preceded by HZ=. A common value on
101 Linux is HZ=100.
102 ENV_PATH (string)
104 If set, it will be used to define the PATH environment variable
105 when a regular user login. The value is a colon separated list of
106 paths (for example /bin:/usr/bin) and can be preceded by PATH=. The
107 default value is PATH=/bin:/usr/bin.
108 ENV_SUPATH (string)
110 If set, it will be used to define the PATH environment variable
111 when the superuser login. The value is a colon separated list of
112 paths (for example /sbin:/bin:/usr/sbin:/usr/bin) and can be
113 preceded by PATH=. The default value is
114 PATH=/sbin:/bin:/usr/sbin:/usr/bin.
115 ENV_TZ (string)
117 If set, it will be used to define the TZ environment variable when
118 a user login. The value can be the name of a timezone preceded by
119 TZ= (for example TZ=CST6CDT), or the full path to the file
120 containing the timezone specification (for example /etc/tzname).
121 If a full path is specified but the file does not exist or cannot
123 be read, the default is to use TZ=CST6CDT.
124 ENVIRON_FILE (string)
126 If this file exists and is readable, login environment will be read
127 from it. Every line should be in the form name=value.
128 Lines starting with a # are treated as comment lines and ignored.
130 ERASECHAR (number)
132 Terminal ERASE character (010 = backspace, 0177 = DEL).
133 The value can be prefixed "0" for an octal value, or "0x" for an
135 hexadecimal value.
136 FAIL_DELAY (number)
138 Delay in seconds before being allowed another attempt after a login
139 failure.
140 FAILLOG_ENAB (boolean)
142 Enable logging and display of /var/log/faillog login failure info.
143 FAKE_SHELL (string)
145 If set, login will execute this shell instead of the users' shell
146 specified in /etc/passwd.
147 FTMP_FILE (string)
149 If defined, login failures will be logged in this file in a utmp
150 format.
151 GID_MAX (number), GID_MIN (number)
153 Range of group IDs used for the creation of regular groups by
154 useradd, groupadd, or newusers.
155 The default value for GID_MIN (resp. GID_MAX) is 1000 (resp.
157 60000).
158 HMAC_CRYPTO_ALGO (string)
160 Used to select the HMAC cryptography algorithm that the
161 pam_timestamp module is going to use to calculate the keyed-hash
162 message authentication code.
163 Note: Check hmac(3) to see the possible algorithms that are
165 available in your system.
166 HOME_MODE (number)
168 The mode for new home directories. If not specified, the UMASK is
169 used to create the mode.
170 useradd and newusers use this to set the mode of the home directory
172 they create.
173 HUSHLOGIN_FILE (string)
175 If defined, this file can inhibit all the usual chatter during the
176 login sequence. If a full pathname is specified, then hushed mode
177 will be enabled if the user's name or shell are found in the file.
178 If not a full pathname, then hushed mode will be enabled if the
179 file exists in the user's home directory.
180 ISSUE_FILE (string)
182 If defined, this file will be displayed before each login prompt.
183 KILLCHAR (number)
185 Terminal KILL character (025 = CTRL/U).
186 The value can be prefixed "0" for an octal value, or "0x" for an
188 hexadecimal value.
189 LASTLOG_ENAB (boolean)
191 Enable logging and display of /var/log/lastlog login time info.
192 LASTLOG_UID_MAX (number)
194 Highest user ID number for which the lastlog entries should be
195 updated. As higher user IDs are usually tracked by remote user
196 identity and authentication services there is no need to create a
197 huge sparse lastlog file for them.
198 No LASTLOG_UID_MAX option present in the configuration means that
200 there is no user ID limit for writing lastlog entries.
201 LOG_OK_LOGINS (boolean)
203 Enable logging of successful logins.
204 LOG_UNKFAIL_ENAB (boolean)
206 Enable display of unknown usernames when login failures are
207 recorded.
208 Note: logging unknown usernames may be a security issue if an user
210 enter her password instead of her login name.
211 LOGIN_RETRIES (number)
213 Maximum number of login retries in case of bad password.
214 LOGIN_STRING (string)
216 The string used for prompting a password. The default is to use
217 "Password: ", or a translation of that string. If you set this
218 variable, the prompt will not be translated.
219 If the string contains %s, this will be replaced by the user's
221 name.
222 LOGIN_TIMEOUT (number)
224 Max time in seconds for login.
225 MAIL_CHECK_ENAB (boolean)
227 Enable checking and display of mailbox status upon login.
228 You should disable it if the shell startup files already check for
230 mail ("mailx -e" or equivalent).
231 MAIL_DIR (string)
233 The mail spool directory. This is needed to manipulate the mailbox
234 when its corresponding user account is modified or deleted. If not
235 specified, a compile-time default is used. The parameter
236 CREATE_MAIL_SPOOL in /etc/default/useradd determines whether the
237 mail spool should be created.
238 MAIL_FILE (string)
240 Defines the location of the users mail spool files relatively to
241 their home directory.
242 The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
244 userdel to create, move, or delete the user's mail spool.
245 If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
247 environment variable.
248 MAX_MEMBERS_PER_GROUP (number)
250 Maximum members per group entry. When the maximum is reached, a new
251 group entry (line) is started in /etc/group (with the same name,
252 same password, and same GID).
253 The default value is 0, meaning that there are no limits in the
255 number of members in a group.
256 This feature (split group) permits to limit the length of lines in
258 the group file. This is useful to make sure that lines for NIS
259 groups are not larger than 1024 characters.
260 If you need to enforce such limit, you can use 25.
262 Note: split groups may not be supported by all tools (even in the
264 Shadow toolsuite). You should not use this variable unless you
265 really need it.
266 MD5_CRYPT_ENAB (boolean)
268 Indicate if passwords must be encrypted using the MD5-based
269 algorithm. If set to yes, new passwords will be encrypted using the
270 MD5-based algorithm compatible with the one used by recent releases
271 of FreeBSD. It supports passwords of unlimited length and longer
272 salt strings. Set to no if you need to copy encrypted passwords to
273 other systems which don't understand the new algorithm. Default is
274 no.
275 This variable is superseded by the ENCRYPT_METHOD variable or by
277 any command line option used to configure the encryption algorithm.
278 This variable is deprecated. You should use ENCRYPT_METHOD.
280 MOTD_FILE (string)
282 If defined, ":" delimited list of "message of the day" files to be
283 displayed upon login.
284 NOLOGINS_FILE (string)
286 If defined, name of file whose presence will inhibit non-root
287 logins. The contents of this file should be a message indicating
288 why logins are inhibited.
289 NONEXISTENT (string)
291 If a system account intentionally does not have a home directory
292 that exists, this string can be provided in the /etc/passwd entry
293 for the account to indicate this. The result is that pwck will not
294 emit a spurious warning for this account.
295 OBSCURE_CHECKS_ENAB (boolean)
297 Enable additional checks upon password changes.
298 PASS_ALWAYS_WARN (boolean)
300 Warn about weak passwords (but still allow them) if you are root.
301 PASS_CHANGE_TRIES (number)
303 Maximum number of attempts to change password if rejected (too
304 easy).
305 PASS_MAX_DAYS (number)
307 The maximum number of days a password may be used. If the password
308 is older than this, a password change will be forced. If not
309 specified, -1 will be assumed (which disables the restriction).
310 PASS_MIN_DAYS (number)
312 The minimum number of days allowed between password changes. Any
313 password changes attempted sooner than this will be rejected. If
314 not specified, 0 will be assumed (which disables the restriction).
315 PASS_WARN_AGE (number)
317 The number of days warning given before a password expires. A zero
318 means warning is given only upon the day of expiration, a negative
319 value means no warning is given. If not specified, no warning will
320 be provided.
321 PASS_MAX_DAYS, PASS_MIN_DAYS and PASS_WARN_AGE are only used at the
323 time of account creation. Any changes to these settings won't affect
324 existing accounts.
325 PASS_MAX_LEN (number), PASS_MIN_LEN (number)
327 Number of significant characters in the password for crypt().
328 PASS_MAX_LEN is 8 by default. Don't change unless your crypt() is
329 better. This is ignored if MD5_CRYPT_ENAB set to yes.
330 PORTTIME_CHECKS_ENAB (boolean)
332 Enable checking of time restrictions specified in /etc/porttime.
333 QUOTAS_ENAB (boolean)
335 Enable setting of resource limits from /etc/limits and ulimit,
336 umask, and niceness from the user's passwd gecos field.
337 SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
339 When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines the
340 number of SHA rounds used by the encryption algorithm by default
341 (when the number of rounds is not specified on the command line).
342 With a lot of rounds, it is more difficult to brute forcing the
344 password. But note also that more CPU resources will be needed to
345 authenticate users.
346 If not specified, the libc will choose the default number of rounds
348 (5000), which is orders of magnitude too low for modern hardware.
349 The values must be inside the 1000-999,999,999 range.
351 If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS
353 values is set, then this value will be used.
354 If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value
356 will be used.
357 SULOG_FILE (string)
359 If defined, all su activity is logged to this file.
360 SU_NAME (string)
362 If defined, the command name to display when running "su -". For
363 example, if this is defined as "su" then a "ps" will display the
364 command is "-su". If not defined, then "ps" would display the name
365 of the shell actually being run, e.g. something like "-sh".
366 SU_WHEEL_ONLY (boolean)
368 If yes, the user must be listed as a member of the first gid 0
369 group in /etc/group (called root on most Linux systems) to be able
370 to su to uid 0 accounts. If the group doesn't exist or is empty, no
371 one will be able to su to uid 0.
372 SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
374 If /etc/subuid exists, the commands useradd and newusers (unless
375 the user already have subordinate group IDs) allocate SUB_GID_COUNT
376 unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each
377 new user.
378 The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are
380 respectively 100000, 600100000 and 65536.
381 SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
383 If /etc/subuid exists, the commands useradd and newusers (unless
384 the user already have subordinate user IDs) allocate SUB_UID_COUNT
385 unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each
386 new user.
387 The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are
389 respectively 100000, 600100000 and 65536.
390 SYS_GID_MAX (number), SYS_GID_MIN (number)
392 Range of group IDs used for the creation of system groups by
393 useradd, groupadd, or newusers.
394 The default value for SYS_GID_MIN (resp. SYS_GID_MAX) is 101
396 (resp. GID_MIN-1).
397 SYS_UID_MAX (number), SYS_UID_MIN (number)
399 Range of user IDs used for the creation of system users by useradd
400 or newusers.
401 The default value for SYS_UID_MIN (resp. SYS_UID_MAX) is 101
403 (resp. UID_MIN-1).
404 SYSLOG_SG_ENAB (boolean)
406 Enable "syslog" logging of sg activity.
407 SYSLOG_SU_ENAB (boolean)
409 Enable "syslog" logging of su activity - in addition to sulog file
410 logging.
411 TTYGROUP (string), TTYPERM (string)
413 The terminal permissions: the login tty will be owned by the
414 TTYGROUP group, and the permissions will be set to TTYPERM.
415 TTYGROUP can be either the name of a group or a numeric group
417 identifier.
418 If TTYGROUP is not defined, then the group ownership of the
420 terminal is set to the user's primary group. If TTYPERM is not
421 defined, then the permissions are set to 0600.
422 If you have a write program which is "setgid" to a special group
424 which owns the terminals, define TTYGROUP to the group number and
425 TTYPERM to 0620. Otherwise leave TTYGROUP commented out and assign
426 TTYPERM to either 622 or 600.
427 TTYTYPE_FILE (string)
429 If defined, file which maps tty line to TERM environment parameter.
430 Each line of the file is in a format something like "vt100 tty01".
431 UID_MAX (number), UID_MIN (number)
433 Range of user IDs used for the creation of regular users by useradd
434 or newusers.
435 The default value for UID_MIN (resp. UID_MAX) is 1000 (resp.
437 60000).
438 ULIMIT (number)
440 Default ulimit value.
441 UMASK (number)
443 The file mode creation mask is initialized to this value. If not
444 specified, the mask will be initialized to 022.
445 useradd and newusers use this mask to set the mode of the home
447 directory they create if HOME_MODE is not set.
448 It is also used by login to define users' initial umask. Note that
450 this mask can be overridden by the user's GECOS line (if
451 QUOTAS_ENAB is set) or by the specification of a limit with the K
452 identifier in limits(5).
453 USERDEL_CMD (string)
455 If defined, this command is run when removing a user. It should
456 remove any at/cron/print jobs etc. owned by the user to be removed
457 (passed as the first argument).
458 The return code of the script is not taken into account.
460 Here is an example script, which removes the user's cron, at and
462 print jobs:
463 #! /bin/sh
465 # Check for the required argument.
467 if [ $# != 1 ]; then
468 echo "Usage: $0 username"
469 exit 1
470 fi
471 # Remove cron jobs.
473 crontab -r -u $1
474 # Remove at jobs.
476 # Note that it will remove any jobs owned by the same UID,
477 # even if it was shared by a different username.
478 AT_SPOOL_DIR=/var/spool/cron/atjobs
479 find $AT_SPOOL_DIR -name "[^.]*" -type f -user $1 -delete \;
480 # Remove print jobs.
482 lprm $1
483 # All done.
485 exit 0
486 USERGROUPS_ENAB (boolean)
490 Enable setting of the umask group bits to be the same as owner bits
491 (examples: 022 -> 002, 077 -> 007) for non-root users, if the uid
492 is the same as gid, and username is the same as the primary group
493 name.
494 If set to yes, userdel will remove the user's group if it contains
496 no more members, and useradd will create by default a group with
497 the name of the user.
498
500 The following cross references show which programs in the shadow
501 password suite use which parameters.
502 chgpasswd
504 ENCRYPT_METHOD MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
505 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS
506 chpasswd
508 ENCRYPT_METHOD MD5_CRYPT_ENAB SHA_CRYPT_MAX_ROUNDS
509 SHA_CRYPT_MIN_ROUNDS
510 gpasswd
512 ENCRYPT_METHOD MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
513 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS
514 groupadd
516 GID_MAX GID_MIN MAX_MEMBERS_PER_GROUP SYS_GID_MAX SYS_GID_MIN
517 groupdel
519 MAX_MEMBERS_PER_GROUP
520 groupmems
522 MAX_MEMBERS_PER_GROUP
523 groupmod
525 MAX_MEMBERS_PER_GROUP
526 grpck
528 MAX_MEMBERS_PER_GROUP
529 grpconv
531 MAX_MEMBERS_PER_GROUP
532 grpunconv
534 MAX_MEMBERS_PER_GROUP
535 lastlog
537 LASTLOG_UID_MAX
538 newgrp / sg
540 SYSLOG_SG_ENAB
541 newusers
543 ENCRYPT_METHOD GID_MAX GID_MIN MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
544 HOME_MODE PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
545 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS SUB_GID_COUNT SUB_GID_MAX
546 SUB_GID_MIN SUB_UID_COUNT SUB_UID_MAX SUB_UID_MIN SYS_GID_MAX
547 SYS_GID_MIN SYS_UID_MAX SYS_UID_MIN UID_MAX UID_MIN UMASK
548 pwck
550 PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
551 pwconv
553 PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
554 useradd
556 CREATE_HOME GID_MAX GID_MIN HOME_MODE LASTLOG_UID_MAX MAIL_DIR
557 MAX_MEMBERS_PER_GROUP PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
558 SUB_GID_COUNT SUB_GID_MAX SUB_GID_MIN SUB_UID_COUNT SUB_UID_MAX
559 SUB_UID_MIN SYS_GID_MAX SYS_GID_MIN SYS_UID_MAX SYS_UID_MIN UID_MAX
560 UID_MIN UMASK
561 userdel
563 MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP USERDEL_CMD
564 USERGROUPS_ENAB
565 usermod
567 LASTLOG_UID_MAX MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP
568
570 login(1), passwd(1), su(1), passwd(5), shadow(5), pam(8).
571shadow-utils 4.14.0 10/03/2023 LOGIN.DEFS(5)