1LOGIN.DEFS(5) File Formats and Conversions 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.
94 Note: this parameter overrides the MD5_CRYPT_ENAB variable.
96 ENV_HZ (string)
98 If set, it will be used to define the HZ environment variable when
99 a user login. The value must be preceded by HZ=. A common value on
100 Linux is HZ=100.
101 ENV_PATH (string)
103 If set, it will be used to define the PATH environment variable
104 when a regular user login. The value is a colon separated list of
105 paths (for example /bin:/usr/bin) and can be preceded by PATH=. The
106 default value is PATH=/bin:/usr/bin.
107 ENV_SUPATH (string)
109 If set, it will be used to define the PATH environment variable
110 when the superuser login. The value is a colon separated list of
111 paths (for example /sbin:/bin:/usr/sbin:/usr/bin) and can be
112 preceded by PATH=. The default value is
113 PATH=/sbin:/bin:/usr/sbin:/usr/bin.
114 ENV_TZ (string)
116 If set, it will be used to define the TZ environment variable when
117 a user login. The value can be the name of a timezone preceded by
118 TZ= (for example TZ=CST6CDT), or the full path to the file
119 containing the timezone specification (for example /etc/tzname).
120 If a full path is specified but the file does not exist or cannot
122 be read, the default is to use TZ=CST6CDT.
123 ENVIRON_FILE (string)
125 If this file exists and is readable, login environment will be read
126 from it. Every line should be in the form name=value.
127 Lines starting with a # are treated as comment lines and ignored.
129 ERASECHAR (number)
131 Terminal ERASE character (010 = backspace, 0177 = DEL).
132 The value can be prefixed "0" for an octal value, or "0x" for an
134 hexadecimal value.
135 FAIL_DELAY (number)
137 Delay in seconds before being allowed another attempt after a login
138 failure.
139 FAILLOG_ENAB (boolean)
141 Enable logging and display of /var/log/faillog login failure info.
142 FAKE_SHELL (string)
144 If set, login will execute this shell instead of the users' shell
145 specified in /etc/passwd.
146 FTMP_FILE (string)
148 If defined, login failures will be logged in this file in a utmp
149 format.
150 GID_MAX (number), GID_MIN (number)
152 Range of group IDs used for the creation of regular groups by
153 useradd, groupadd, or newusers.
154 The default value for GID_MIN (resp. GID_MAX) is 1000 (resp.
156 60000).
157 HOME_MODE (number)
159 The mode for new home directories. If not specified, the UMASK is
160 used to create the mode.
161 useradd and newusers use this to set the mode of the home directory
163 they create.
164 HUSHLOGIN_FILE (string)
166 If defined, this file can inhibit all the usual chatter during the
167 login sequence. If a full pathname is specified, then hushed mode
168 will be enabled if the user's name or shell are found in the file.
169 If not a full pathname, then hushed mode will be enabled if the
170 file exists in the user's home directory.
171 ISSUE_FILE (string)
173 If defined, this file will be displayed before each login prompt.
174 KILLCHAR (number)
176 Terminal KILL character (025 = CTRL/U).
177 The value can be prefixed "0" for an octal value, or "0x" for an
179 hexadecimal value.
180 LASTLOG_ENAB (boolean)
182 Enable logging and display of /var/log/lastlog login time info.
183 LASTLOG_UID_MAX (number)
185 Highest user ID number for which the lastlog entries should be
186 updated. As higher user IDs are usually tracked by remote user
187 identity and authentication services there is no need to create a
188 huge sparse lastlog file for them.
189 No LASTLOG_UID_MAX option present in the configuration means that
191 there is no user ID limit for writing lastlog entries.
192 LOG_OK_LOGINS (boolean)
194 Enable logging of successful logins.
195 LOG_UNKFAIL_ENAB (boolean)
197 Enable display of unknown usernames when login failures are
198 recorded.
199 Note: logging unknown usernames may be a security issue if an user
201 enter her password instead of her login name.
202 LOGIN_RETRIES (number)
204 Maximum number of login retries in case of bad password.
205 LOGIN_STRING (string)
207 The string used for prompting a password. The default is to use
208 "Password: ", or a translation of that string. If you set this
209 variable, the prompt will not be translated.
210 If the string contains %s, this will be replaced by the user's
212 name.
213 LOGIN_TIMEOUT (number)
215 Max time in seconds for login.
216 MAIL_CHECK_ENAB (boolean)
218 Enable checking and display of mailbox status upon login.
219 You should disable it if the shell startup files already check for
221 mail ("mailx -e" or equivalent).
222 MAIL_DIR (string)
224 The mail spool directory. This is needed to manipulate the mailbox
225 when its corresponding user account is modified or deleted. If not
226 specified, a compile-time default is used.
227 MAIL_FILE (string)
229 Defines the location of the users mail spool files relatively to
230 their home directory.
231 The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
233 userdel to create, move, or delete the user's mail spool.
234 If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
236 environment variable.
237 MAX_MEMBERS_PER_GROUP (number)
239 Maximum members per group entry. When the maximum is reached, a new
240 group entry (line) is started in /etc/group (with the same name,
241 same password, and same GID).
242 The default value is 0, meaning that there are no limits in the
244 number of members in a group.
245 This feature (split group) permits to limit the length of lines in
247 the group file. This is useful to make sure that lines for NIS
248 groups are not larger than 1024 characters.
249 If you need to enforce such limit, you can use 25.
251 Note: split groups may not be supported by all tools (even in the
253 Shadow toolsuite). You should not use this variable unless you
254 really need it.
255 MD5_CRYPT_ENAB (boolean)
257 Indicate if passwords must be encrypted using the MD5-based
258 algorithm. If set to yes, new passwords will be encrypted using the
259 MD5-based algorithm compatible with the one used by recent releases
260 of FreeBSD. It supports passwords of unlimited length and longer
261 salt strings. Set to no if you need to copy encrypted passwords to
262 other systems which don't understand the new algorithm. Default is
263 no.
264 This variable is superseded by the ENCRYPT_METHOD variable or by
266 any command line option used to configure the encryption algorithm.
267 This variable is deprecated. You should use ENCRYPT_METHOD.
269 MOTD_FILE (string)
271 If defined, ":" delimited list of "message of the day" files to be
272 displayed upon login.
273 NOLOGINS_FILE (string)
275 If defined, name of file whose presence will inhibit non-root
276 logins. The contents of this file should be a message indicating
277 why logins are inhibited.
278 OBSCURE_CHECKS_ENAB (boolean)
280 Enable additional checks upon password changes.
281 PASS_ALWAYS_WARN (boolean)
283 Warn about weak passwords (but still allow them) if you are root.
284 PASS_CHANGE_TRIES (number)
286 Maximum number of attempts to change password if rejected (too
287 easy).
288 PASS_MAX_DAYS (number)
290 The maximum number of days a password may be used. If the password
291 is older than this, a password change will be forced. If not
292 specified, -1 will be assumed (which disables the restriction).
293 PASS_MIN_DAYS (number)
295 The minimum number of days allowed between password changes. Any
296 password changes attempted sooner than this will be rejected. If
297 not specified, -1 will be assumed (which disables the restriction).
298 PASS_WARN_AGE (number)
300 The number of days warning given before a password expires. A zero
301 means warning is given only upon the day of expiration, a negative
302 value means no warning is given. If not specified, no warning will
303 be provided.
304 PASS_MAX_DAYS, PASS_MIN_DAYS and PASS_WARN_AGE are only used at the
306 time of account creation. Any changes to these settings won't affect
307 existing accounts.
308 PASS_MAX_LEN (number), PASS_MIN_LEN (number)
310 Number of significant characters in the password for crypt().
311 PASS_MAX_LEN is 8 by default. Don't change unless your crypt() is
312 better. This is ignored if MD5_CRYPT_ENAB set to yes.
313 PORTTIME_CHECKS_ENAB (boolean)
315 Enable checking of time restrictions specified in /etc/porttime.
316 QUOTAS_ENAB (boolean)
318 Enable setting of resource limits from /etc/limits and ulimit,
319 umask, and niceness from the user's passwd gecos field.
320 SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
322 When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines the
323 number of SHA rounds used by the encryption algorithm by default
324 (when the number of rounds is not specified on the command line).
325 With a lot of rounds, it is more difficult to brute forcing the
327 password. But note also that more CPU resources will be needed to
328 authenticate users.
329 If not specified, the libc will choose the default number of rounds
331 (5000).
332 The values must be inside the 1000-999,999,999 range.
334 If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS
336 values is set, then this value will be used.
337 If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value
339 will be used.
340 SULOG_FILE (string)
342 If defined, all su activity is logged to this file.
343 SU_NAME (string)
345 If defined, the command name to display when running "su -". For
346 example, if this is defined as "su" then a "ps" will display the
347 command is "-su". If not defined, then "ps" would display the name
348 of the shell actually being run, e.g. something like "-sh".
349 SU_WHEEL_ONLY (boolean)
351 If yes, the user must be listed as a member of the first gid 0
352 group in /etc/group (called root on most Linux systems) to be able
353 to su to uid 0 accounts. If the group doesn't exist or is empty, no
354 one will be able to su to uid 0.
355 SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
357 If /etc/subuid exists, the commands useradd and newusers (unless
358 the user already have subordinate group IDs) allocate SUB_GID_COUNT
359 unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each
360 new user.
361 The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are
363 respectively 100000, 600100000 and 65536.
364 SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
366 If /etc/subuid exists, the commands useradd and newusers (unless
367 the user already have subordinate user IDs) allocate SUB_UID_COUNT
368 unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each
369 new user.
370 The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are
372 respectively 100000, 600100000 and 65536.
373 SYS_GID_MAX (number), SYS_GID_MIN (number)
375 Range of group IDs used for the creation of system groups by
376 useradd, groupadd, or newusers.
377 The default value for SYS_GID_MIN (resp. SYS_GID_MAX) is 101
379 (resp. GID_MIN-1).
380 SYS_UID_MAX (number), SYS_UID_MIN (number)
382 Range of user IDs used for the creation of system users by useradd
383 or newusers.
384 The default value for SYS_UID_MIN (resp. SYS_UID_MAX) is 101
386 (resp. UID_MIN-1).
387 SYSLOG_SG_ENAB (boolean)
389 Enable "syslog" logging of sg activity.
390 SYSLOG_SU_ENAB (boolean)
392 Enable "syslog" logging of su activity - in addition to sulog file
393 logging.
394 TTYGROUP (string), TTYPERM (string)
396 The terminal permissions: the login tty will be owned by the
397 TTYGROUP group, and the permissions will be set to TTYPERM.
398 By default, the ownership of the terminal is set to the user's
400 primary group and the permissions are set to 0600.
401 TTYGROUP can be either the name of a group or a numeric group
403 identifier.
404 If you have a write program which is "setgid" to a special group
406 which owns the terminals, define TTYGROUP to the group number and
407 TTYPERM to 0620. Otherwise leave TTYGROUP commented out and assign
408 TTYPERM to either 622 or 600.
409 TTYTYPE_FILE (string)
411 If defined, file which maps tty line to TERM environment parameter.
412 Each line of the file is in a format something like "vt100 tty01".
413 UID_MAX (number), UID_MIN (number)
415 Range of user IDs used for the creation of regular users by useradd
416 or newusers.
417 The default value for UID_MIN (resp. UID_MAX) is 1000 (resp.
419 60000).
420 ULIMIT (number)
422 Default ulimit value.
423 UMASK (number)
425 The file mode creation mask is initialized to this value. If not
426 specified, the mask will be initialized to 022.
427 useradd and newusers use this mask to set the mode of the home
429 directory they create if HOME_MODE is not set.
430 It is also used by login to define users' initial umask. Note that
432 this mask can be overridden by the user's GECOS line (if
433 QUOTAS_ENAB is set) or by the specification of a limit with the K
434 identifier in limits(5).
435 USERDEL_CMD (string)
437 If defined, this command is run when removing a user. It should
438 remove any at/cron/print jobs etc. owned by the user to be removed
439 (passed as the first argument).
440 The return code of the script is not taken into account.
442 Here is an example script, which removes the user's cron, at and
444 print jobs:
445 #! /bin/sh
447 # Check for the required argument.
449 if [ $# != 1 ]; then
450 echo "Usage: $0 username"
451 exit 1
452 fi
453 # Remove cron jobs.
455 crontab -r -u $1
456 # Remove at jobs.
458 # Note that it will remove any jobs owned by the same UID,
459 # even if it was shared by a different username.
460 AT_SPOOL_DIR=/var/spool/cron/atjobs
461 find $AT_SPOOL_DIR -name "[^.]*" -type f -user $1 -delete \;
462 # Remove print jobs.
464 lprm $1
465 # All done.
467 exit 0
468 USERGROUPS_ENAB (boolean)
472 Enable setting of the umask group bits to be the same as owner bits
473 (examples: 022 -> 002, 077 -> 007) for non-root users, if the uid
474 is the same as gid, and username is the same as the primary group
475 name.
476 If set to yes, userdel will remove the user's group if it contains
478 no more members, and useradd will create by default a group with
479 the name of the user.
480
482 The following cross references show which programs in the shadow
483 password suite use which parameters.
484 chgpasswd
486 ENCRYPT_METHOD MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
487 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS
488 chpasswd
490 ENCRYPT_METHOD MD5_CRYPT_ENAB SHA_CRYPT_MAX_ROUNDS
491 SHA_CRYPT_MIN_ROUNDS
492 gpasswd
494 ENCRYPT_METHOD MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
495 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS
496 groupadd
498 GID_MAX GID_MIN MAX_MEMBERS_PER_GROUP SYS_GID_MAX SYS_GID_MIN
499 groupdel
501 MAX_MEMBERS_PER_GROUP
502 groupmems
504 MAX_MEMBERS_PER_GROUP
505 groupmod
507 MAX_MEMBERS_PER_GROUP
508 grpck
510 MAX_MEMBERS_PER_GROUP
511 grpconv
513 MAX_MEMBERS_PER_GROUP
514 grpunconv
516 MAX_MEMBERS_PER_GROUP
517 lastlog
519 LASTLOG_UID_MAX
520 newgrp / sg
522 SYSLOG_SG_ENAB
523 newusers
525 ENCRYPT_METHOD GID_MAX GID_MIN MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
526 HOME_MODE PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
527 SHA_CRYPT_MAX_ROUNDS SHA_CRYPT_MIN_ROUNDS SUB_GID_COUNT SUB_GID_MAX
528 SUB_GID_MIN SUB_UID_COUNT SUB_UID_MAX SUB_UID_MIN SYS_GID_MAX
529 SYS_GID_MIN SYS_UID_MAX SYS_UID_MIN UID_MAX UID_MIN UMASK
530 pwck
532 PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
533 pwconv
535 PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
536 useradd
538 CREATE_HOME GID_MAX GID_MIN HOME_MODE LASTLOG_UID_MAX MAIL_DIR
539 MAX_MEMBERS_PER_GROUP PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE
540 SUB_GID_COUNT SUB_GID_MAX SUB_GID_MIN SUB_UID_COUNT SUB_UID_MAX
541 SUB_UID_MIN SYS_GID_MAX SYS_GID_MIN SYS_UID_MAX SYS_UID_MIN UID_MAX
542 UID_MIN UMASK
543 userdel
545 MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP USERDEL_CMD
546 USERGROUPS_ENAB
547 usermod
549 LASTLOG_UID_MAX MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP
550
552 login(1), passwd(1), su(1), passwd(5), shadow(5), pam(8).
553shadow-utils 4.8.1 03/29/2021 LOGIN.DEFS(5)