Technical Details
$
cat /etc/pam.d/common-password
$
cat /etc/login.defs
#
# 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 therefore be configured elsewhere. Refer to
# /etc/pam.d/system-auth for more information.
#
#
# Delay in seconds before being allowed another attempt after a login failure
# Note: When PAM is used, some modules may enforce a minimum delay (e.g.
# pam_unix(8) enforces a 2s delay)
#
#FAIL_DELAY 3
# Currently FAILLOG_ENAB is not supported
#
# Enable display of unknown usernames when login(1) failures are recorded.
#
#LOG_UNKFAIL_ENAB no
# Currently LOG_OK_LOGINS is not supported
# Currently LASTLOG_ENAB is not supported
#
# Limit the highest user ID number for which the lastlog entries should
# be updated.
#
# No LASTLOG_UID_MAX means that there is no user ID limit for writing
# lastlog entries.
#
#LASTLOG_UID_MAX
# Currently MAIL_CHECK_ENAB is not supported
# Currently OBSCURE_CHECKS_ENAB is not supported
# Currently PORTTIME_CHECKS_ENAB is not supported
# Currently QUOTAS_ENAB is not supported
# Currently SYSLOG_SU_ENAB is not supported
#
# Enable "syslog" logging of newgrp(1) and sg(1) activity.
#
#SYSLOG_SG_ENAB yes
# Currently CONSOLE is not supported
# Currently SULOG_FILE is not supported
# Currently MOTD_FILE is not supported
# Currently ISSUE_FILE is not supported
# Currently TTYTYPE_FILE is not supported
# Currently FTMP_FILE is not supported
# Currently NOLOGINS_FILE is not supported
# Currently SU_NAME is not supported
# *REQUIRED*
# Directory where mailboxes reside, _or_ name of file, relative to the
# home directory. If you _do_ define both, MAIL_DIR takes precedence.
#
MAIL_DIR /var/spool/mail
#MAIL_FILE .mail
#
# If defined, file which inhibits all the usual chatter during the login
# sequence. If a full pathname, 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.
#
#HUSHLOGIN_FILE .hushlogin
#HUSHLOGIN_FILE /etc/hushlogins
# Currently ENV_TZ is not supported
# Currently ENV_HZ is not supported
#
# The default PATH settings, for superuser and normal users.
#
# (they are minimal, add the rest in the shell startup files)
#ENV_SUPATH PATH=/sbin:/bin:/usr/sbin:/usr/bin
#ENV_PATH PATH=/bin:/usr/bin
#
# Terminal permissions
#
# TTYGROUP Login tty will be assigned this group ownership.
# TTYPERM Login tty will be set to this permission.
#
# If you have a write(1) program which is "setgid" to a special group
# which owns the terminals, define TTYGROUP as the number of such group
# and TTYPERM as 0620. Otherwise leave TTYGROUP commented out and
# set TTYPERM to either 622 or 600.
#
#TTYGROUP tty
#TTYPERM 0600
# Currently ERASECHAR, KILLCHAR and ULIMIT are not supported
# Default initial "umask" value used by login(1) on non-PAM enabled systems.
# Default "umask" value for pam_umask(8) on PAM enabled systems.
# UMASK is also used by useradd(8) and newusers(8) to set the mode for new
# home directories if HOME_MODE is not set.
# 022 is the default value, but 027, or even 077, could be considered
# for increased privacy. There is no One True Answer here: each sysadmin
# must make up their mind.
UMASK 022
# HOME_MODE is used by useradd(8) and newusers(8) to set the mode for new
# home directories.
# If HOME_MODE is not set, the value of UMASK is used to create the mode.
HOME_MODE 0700
# Password aging controls:
#
# PASS_MAX_DAYS Maximum number of days a password may be used.
# PASS_MIN_DAYS Minimum number of days allowed between password changes.
# PASS_MIN_LEN Minimum acceptable password length.
# PASS_WARN_AGE Number of days warning given before a password expires.
#
PASS_MAX_DAYS 99999
PASS_MIN_DAYS 0
PASS_MIN_LEN 8
PASS_WARN_AGE 7
# Currently SU_WHEEL_ONLY is not supported
# Currently CRACKLIB_DICTPATH is not supported
#
# Min/max values for automatic uid selection in useradd(8)
#
UID_MIN 1000
UID_MAX 60000
# System accounts
SYS_UID_MIN 201
SYS_UID_MAX 999
# Extra per user uids
SUB_UID_MIN 524288
SUB_UID_MAX 600100000
SUB_UID_COUNT 65536
#
# Min/max values for automatic gid selection in groupadd(8)
#
GID_MIN 1000
GID_MAX 60000
# System accounts
SYS_GID_MIN 201
SYS_GID_MAX 999
# Extra per user group ids
SUB_GID_MIN 524288
SUB_GID_MAX 600100000
SUB_GID_COUNT 65536
#
# Max number of login(1) retries if password is bad
#
#LOGIN_RETRIES 3
#
# Max time in seconds for login(1)
#
#LOGIN_TIMEOUT 60
#
# Maximum number of attempts to change password if rejected (too easy)
#
PASS_CHANGE_TRIES 5
#
# Warn about weak passwords (but still allow them) if you are root.
#
PASS_ALWAYS_WARN yes
#
# Number of significant characters in the password for crypt().
# Default is 8, don't change unless your crypt() is better.
# Ignored if MD5_CRYPT_ENAB set to "yes".
#
#PASS_MAX_LEN 8
# Currently CHFN_AUTH is not supported
#
# Which fields may be changed by regular users using chfn(1) - use
# any combination of letters "frwh" (full name, room number, work
# phone, home phone). If not defined, no changes are allowed.
# For backward compatibility, "yes" = "rwh" and "no" = "frwh".
#
#CHFN_RESTRICT rwh
# Currently LOGIN_STRING is not supported
# Currently MD5_CRYPT_ENAB is not supported
#
# If set to MD5, MD5-based algorithm will be used for encrypting password
# If set to SHA256, SHA256-based algorithm will be used for encrypting password
# If set to SHA512, SHA512-based algorithm will be used for encrypting password
# If set to BCRYPT, BCRYPT-based algorithm will be used for encrypting password
# If set to YESCRYPT, YESCRYPT-based algorithm will be used for encrypting password
# If set to DES, DES-based algorithm will be used for encrypting password (default)
#
ENCRYPT_METHOD YESCRYPT
#
# Only works if ENCRYPT_METHOD is set to SHA256 or SHA512.
#
# Define the number of SHA rounds.
# With a lot of rounds, it is more difficult to brute-force the password.
# However, more CPU resources will be needed to authenticate users if
# this value is increased.
#
# If not specified, the libc will choose the default number of rounds (5000).
# The values must be within the 1000-999999999 range.
#
#SHA_CRYPT_MAX_ROUNDS 5000
# Currently SHA_CRYPT_MIN_ROUNDS is not supported
#
# Only works if ENCRYPT_METHOD is set to BCRYPT.
#
# Define the number of BCRYPT rounds.
# With a lot of rounds, it is more difficult to brute-force the password.
# However, more CPU resources will be needed to authenticate users if
# this value is increased.
#
# If not specified, 13 rounds will be attempted.
# If only one of the MIN or MAX values is set, then this value will be used.
# If MIN > MAX, the highest value will be used.
#
#BCRYPT_MIN_ROUNDS 13
#BCRYPT_MAX_ROUNDS 31
#
# Only works if ENCRYPT_METHOD is set to YESCRYPT.
#
# Define the YESCRYPT cost factor.
# With a higher cost factor, it is more difficult to brute-force the password.
# However, more CPU time and more memory will be needed to authenticate users
# if this value is increased.
#
# If not specified, a cost factor of 5 will be used.
# The value must be within the 1-11 range.
#
#YESCRYPT_COST_FACTOR 5
# Currently CONSOLE_GROUPS is not supported
#
# Should login be allowed if we can't cd to the home directory?
# Default is yes.
#
#DEFAULT_HOME yes
# Currently ENVIRON_FILE is not supported
#
# If defined, this command is run when removing a user.
# It should remove any at/cron/print jobs etc. owned by
# the user to be removed (passed as the first argument).
#
#USERDEL_CMD /usr/sbin/userdel_local
#
# Enables userdel(8) to remove user groups if no members exist.
#
USERGROUPS_ENAB yes
#
# If set to a non-zero number, the shadow utilities will make sure that
# groups never have more than this number of users on one line.
# This permits to support split groups (groups split into multiple lines,
# with the same group ID, to avoid limitation of the line length in the
# group file).
#
# 0 is the default value and disables this feature.
#
#MAX_MEMBERS_PER_GROUP 0
#
# If useradd(8) should create home directories for users by default (non
# system users only).
# This option is overridden with the -M or -m flags on the useradd(8)
# command-line.
#
CREATE_HOME yes
#
# Force use shadow, even if shadow passwd & shadow group files are
# missing.
#
#FORCE_SHADOW yes
#
# Select the HMAC cryptography algorithm.
# Used in pam_timestamp module to calculate the keyed-hash message
# authentication code.
#
# Note: It is recommended to check hmac(3) to see the possible algorithms
# that are available in your system.
#
HMAC_CRYPTO_ALGO SHA512