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login.defs


DESCRIPTION

       The /etc/login.defs file defines the site-specific configuration for
       the shadow password suite. This file is required. Absence of this file
       will not prevent system operation, but will probably result in
       undesirable operation.

       This file is a readable text file, each line of the file describing one
       configuration parameter. The lines consist of a configuration name and
       value, separated by whitespace. Blank lines and comment lines are
       ignored. Comments are introduced with a "#" pound sign and the pound
       sign must be the first non-white character of the line.

       Parameter values may be of four types: strings, booleans, numbers, and
       long numbers. A string is comprised of any printable characters. A
       boolean should be either the value yes or no. An undefined boolean
       parameter or one with a value other than these will be given a no
       value. Numbers (both regular and long) may be either decimal values,
       octal values (precede the value with 0) or hexadecimal values (precede
       the value with 0x). The maximum value of the regular and long numeric
       parameters is machine-dependent.

       Please note that the parameters in this configuration file control the
       behavior of the tools from the shadow-utils component. None of these
       tools uses the PAM mechanism, and the utilities that use PAM (such as
       the passwd command) should be configured elsewhere. The only values
       that affect PAM modules are ENCRYPT_METHOD and SHA_CRYPT_MAX_ROUNDS for
       pam_unix module, FAIL_DELAY for pam_faildelay module, and UMASK for
       pam_umask module. Refer to pam(8) for more information.

       The following configuration items are provided:

       CHFN_AUTH (boolean)
           If yes, the chfn program will require authentication before making
           any changes, unless run by the superuser.

       CHFN_RESTRICT (string)
           This parameter specifies which values in the gecos field of the
           /etc/passwd file may be changed by regular users using the chfn
           program. It can be any combination of letters f, r, w, h, for Full
           name, Room number, Work phone, and Home phone, respectively. For
           backward compatibility, yes is equivalent to rwh and no is
           equivalent to frwh. If not specified, only the superuser can make
           any changes. The most restrictive setting is better achieved by not
           installing chfn SUID.

       CHSH_AUTH (boolean)
           If yes, the chsh program will require authentication before making
           any changes, unless run by the superuser.

       CONSOLE (string)
           If defined, either full pathname of a file containing device names
           (one per line) or a ":" delimited list of device names. Root logins

       CREATE_HOME (boolean)
           Indicate if a home directory should be created by default for new
           users.

           This setting does not apply to system users, and can be overridden
           on the command line.

       DEFAULT_HOME (boolean)
           Indicate if login is allowed if we can't cd to the home directory.
           Default is no.

           If set to yes, the user will login in the root (/) directory if it
           is not possible to cd to her home directory.

       ENCRYPT_METHOD (string)
           This defines the system default encryption algorithm for encrypting
           passwords (if no algorithm are specified on the command line).

           It can take one of these values: DES (default), MD5, SHA256,
           SHA512.

           Note: this parameter overrides the MD5_CRYPT_ENAB variable.

       ENV_HZ (string)
           If set, it will be used to define the HZ environment variable when
           a user login. The value must be preceded by HZ=. A common value on
           Linux is HZ=100.

       ENV_PATH (string)
           If set, it will be used to define the PATH environment variable
           when a regular user login. The value is a colon separated list of
           paths (for example /bin:/usr/bin) and can be preceded by PATH=. The
           default value is PATH=/bin:/usr/bin.

       ENV_SUPATH (string)
           If set, it will be used to define the PATH environment variable
           when the superuser login. The value is a colon separated list of
           paths (for example /sbin:/bin:/usr/sbin:/usr/bin) and can be
           preceded by PATH=. The default value is
           PATH=/sbin:/bin:/usr/sbin:/usr/bin.

       ENV_TZ (string)
           If set, it will be used to define the TZ environment variable when
           a user login. The value can be the name of a timezone preceded by
           TZ= (for example TZ=CST6CDT), or the full path to the file
           containing the timezone specification (for example /etc/tzname).

           If a full path is specified but the file does not exist or cannot
           be read, the default is to use TZ=CST6CDT.

       ENVIRON_FILE (string)
           If this file exists and is readable, login environment will be read

       FAILLOG_ENAB (boolean)
           Enable logging and display of /var/log/faillog login failure info.

       FAKE_SHELL (string)
           If set, login will execute this shell instead of the users' shell
           specified in /etc/passwd.

       FTMP_FILE (string)
           If defined, login failures will be logged in this file in a utmp
           format.

       GID_MAX (number), GID_MIN (number)
           Range of group IDs used for the creation of regular groups by
           useradd, groupadd, or newusers.

           The default value for GID_MIN (resp.  GID_MAX) is 1000 (resp.
           60000).

       HUSHLOGIN_FILE (string)
           If defined, this file can inhibit all the usual chatter during the
           login sequence. If a full pathname is specified, then hushed mode
           will be enabled if the user's name or shell are found in the file.
           If not a full pathname, then hushed mode will be enabled if the
           file exists in the user's home directory.

       ISSUE_FILE (string)
           If defined, this file will be displayed before each login prompt.

       KILLCHAR (number)
           Terminal KILL character (025 = CTRL/U).

           The value can be prefixed "0" for an octal value, or "0x" for an
           hexadecimal value.

       LASTLOG_ENAB (boolean)
           Enable logging and display of /var/log/lastlog login time info.

       LOG_OK_LOGINS (boolean)
           Enable logging of successful logins.

       LOG_UNKFAIL_ENAB (boolean)
           Enable display of unknown usernames when login failures are
           recorded.

           Note: logging unknown usernames may be a security issue if an user
           enter her password instead of her login name.

       LOGIN_RETRIES (number)
           Maximum number of login retries in case of bad password.

       LOGIN_STRING (string)
           The string used for prompting a password. The default is to use

       MAIL_DIR (string)
           The mail spool directory. This is needed to manipulate the mailbox
           when its corresponding user account is modified or deleted. If not
           specified, a compile-time default is used.

       MAIL_FILE (string)
           Defines the location of the users mail spool files relatively to
           their home directory.

       The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
       userdel to create, move, or delete the user's mail spool.

       If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
       environment variable.

       MAX_MEMBERS_PER_GROUP (number)
           Maximum members per group entry. When the maximum is reached, a new
           group entry (line) is started in /etc/group (with the same name,
           same password, and same GID).

           The default value is 0, meaning that there are no limits in the
           number of members in a group.

           This feature (split group) permits to limit the length of lines in
           the group file. This is useful to make sure that lines for NIS
           groups are not larger than 1024 characters.

           If you need to enforce such limit, you can use 25.

           Note: split groups may not be supported by all tools (even in the
           Shadow toolsuite). You should not use this variable unless you
           really need it.

       MD5_CRYPT_ENAB (boolean)
           Indicate if passwords must be encrypted using the MD5-based
           algorithm. If set to yes, new passwords will be encrypted using the
           MD5-based algorithm compatible with the one used by recent releases
           of FreeBSD. It supports passwords of unlimited length and longer
           salt strings. Set to no if you need to copy encrypted passwords to
           other systems which don't understand the new algorithm. Default is
           no.

           This variable is superseded by the ENCRYPT_METHOD variable or by
           any command line option used to configure the encryption algorithm.

           This variable is deprecated. You should use ENCRYPT_METHOD.

       MOTD_FILE (string)
           If defined, ":" delimited list of "message of the day" files to be
           displayed upon login.


       PASS_MAX_DAYS (number)
           The maximum number of days a password may be used. If the password
           is older than this, a password change will be forced. If not
           specified, -1 will be assumed (which disables the restriction).

       PASS_MIN_DAYS (number)
           The minimum number of days allowed between password changes. Any
           password changes attempted sooner than this will be rejected. If
           not specified, -1 will be assumed (which disables the restriction).

       PASS_WARN_AGE (number)
           The number of days warning given before a password expires. A zero
           means warning is given only upon the day of expiration, a negative
           value means no warning is given. If not specified, no warning will
           be provided.

       PASS_MAX_DAYS, PASS_MIN_DAYS and PASS_WARN_AGE are only used at the
       time of account creation. Any changes to these settings won't affect
       existing accounts.

       PASS_MAX_LEN (number), PASS_MIN_LEN (number)
           Number of significant characters in the password for crypt().
           PASS_MAX_LEN is 8 by default. Don't change unless your crypt() is
           better. This is ignored if MD5_CRYPT_ENAB set to yes.

       PORTTIME_CHECKS_ENAB (boolean)
           Enable checking of time restrictions specified in /etc/porttime.

       QUOTAS_ENAB (boolean)
           Enable setting of resource limits from /etc/limits and ulimit,
           umask, and niceness from the user's passwd gecos field.

       SHA_CRYPT_MIN_ROUNDS (number), SHA_CRYPT_MAX_ROUNDS (number)
           When ENCRYPT_METHOD is set to SHA256 or SHA512, this defines the
           number of SHA rounds used by the encryption algorithm by default
           (when the number of rounds is not specified on the command line).

           With a lot of rounds, it is more difficult to brute forcing the
           password. But note also that more CPU resources will be needed to
           authenticate users.

           If not specified, the libc will choose the default number of rounds
           (5000).

           The values must be inside the 1000-999,999,999 range.

           If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS
           values is set, then this value will be used.

           If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value
           will be used.
           one will be able to su to uid 0.

       SYS_GID_MAX (number), SYS_GID_MIN (number)
           Range of group IDs used for the creation of system groups by
           useradd, groupadd, or newusers.

           The default value for SYS_GID_MIN (resp.  SYS_GID_MAX) is 101
           (resp.  GID_MIN-1).

       SYS_UID_MAX (number), SYS_UID_MIN (number)
           Range of user IDs used for the creation of system users by useradd
           or newusers.

           The default value for SYS_UID_MIN (resp.  SYS_UID_MAX) is 101
           (resp.  UID_MIN-1).

       SYSLOG_SG_ENAB (boolean)
           Enable "syslog" logging of sg activity.

       SYSLOG_SU_ENAB (boolean)
           Enable "syslog" logging of su activity - in addition to sulog file
           logging.

       TTYGROUP (string), TTYPERM (string)
           The terminal permissions: the login tty will be owned by the
           TTYGROUP group, and the permissions will be set to TTYPERM.

           By default, the ownership of the terminal is set to the user's
           primary group and the permissions are set to 0600.

           TTYGROUP can be either the name of a group or a numeric group
           identifier.

           If you have a write program which is "setgid" to a special group
           which owns the terminals, define TTYGROUP to the group number and
           TTYPERM to 0620. Otherwise leave TTYGROUP commented out and assign
           TTYPERM to either 622 or 600.

       TTYTYPE_FILE (string)
           If defined, file which maps tty line to TERM environment parameter.
           Each line of the file is in a format something like "vt100 tty01".

       UID_MAX (number), UID_MIN (number)
           Range of user IDs used for the creation of regular users by useradd
           or newusers.

           The default value for UID_MIN (resp.  UID_MAX) is 1000 (resp.
           60000).

       ULIMIT (number)
           Default ulimit value.

           remove any at/cron/print jobs etc. owned by the user to be removed
           (passed as the first argument).

           The return code of the script is not taken into account.

           Here is an example script, which removes the user's cron, at and
           print jobs:

               #! /bin/sh

               # Check for the required argument.
               if [ $# != 1 ]; then
                    echo "Usage: $0 username"
                    exit 1
               fi

               # Remove cron jobs.
               crontab -r -u $1

               # Remove at jobs.
               # Note that it will remove any jobs owned by the same UID,
               # even if it was shared by a different username.
               AT_SPOOL_DIR=/var/spool/cron/atjobs
               find $AT_SPOOL_DIR -name "[^.]*" -type f -user $1 -delete \;

               # Remove print jobs.
               lprm $1

               # All done.
               exit 0

       USERGROUPS_ENAB (boolean)
           Enable setting of the umask group bits to be the same as owner bits
           (examples: 022 -> 002, 077 -> 007) for non-root users, if the uid
           is the same as gid, and username is the same as the primary group
           name.

           If set to yes, userdel will remove the user's group if it contains
           no more members, and useradd will create by default a group with
           the name of the user.


CROSS REFERENCES

       The following cross references show which programs in the shadow
       password suite use which parameters.

       chpasswd
           ENCRYPT_METHOD MD5_CRYPT_ENABSHA_CRYPT_MAX_ROUNDS
           SHA_CRYPT_MIN_ROUNDS

       gpasswd

       grpck
           MAX_MEMBERS_PER_GROUP

       grpconv
           MAX_MEMBERS_PER_GROUP

       grpunconv
           MAX_MEMBERS_PER_GROUP

       newgrp / sg
           SYSLOG_SG_ENAB

       newusers
           ENCRYPT_METHOD GID_MAX GID_MIN MAX_MEMBERS_PER_GROUP MD5_CRYPT_ENAB
           PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE SHA_CRYPT_MAX_ROUNDS
           SHA_CRYPT_MIN_ROUNDS SYS_GID_MAX SYS_GID_MIN SYS_UID_MAX
           SYS_UID_MIN UID_MAX UID_MIN UMASK

       pwck
           PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE

       pwconv
           PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE

       useradd
           CREATE_HOME GID_MAX GID_MIN MAIL_DIR MAX_MEMBERS_PER_GROUP
           PASS_MAX_DAYS PASS_MIN_DAYS PASS_WARN_AGE SYS_GID_MAX SYS_GID_MIN
           SYS_UID_MAX SYS_UID_MIN UID_MAX UID_MIN UMASK

       userdel
           MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP USERDEL_CMD
           USERGROUPS_ENAB

       usermod
           MAIL_DIR MAIL_FILE MAX_MEMBERS_PER_GROUP


SEE ALSO

       login(1), passwd(1), su(1), passwd(5), shadow(5), pam(8).


shadow-utils 4.1.5.1 11/05/2016 LOGIN.DEFS(5)



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