Manual: pam_extrausers
PAM_EXTRAUSERS(8) Linux-PAM Manual PAM_EXTRAUSERS(8)
NAME
pam_extrausers - Module for libnss-extrausers authentication
SYNOPSIS
pam_extrausers.so [...]
DESCRIPTION
This is similar to the standard Unix authentication module pam_unix. But instead of using /etc/passwd and
/etc/shadow, it uses /var/lib/extrausers/passwd and /var/lib/extrausers/shadow.
The account component performs the task of establishing the status of the user's account and password based on the
following shadow elements: expire, last_change, max_change, min_change, warn_change. In the case of the latter, it
may offer advice to the user on changing their password or, through the PAM_AUTHTOKEN_REQD return, delay giving
service to the user until they have established a new password. The entries listed above are documented in the
shadow(5) manual page. Should the user's record not contain one or more of these entries, the corresponding shadow
check is not performed.
The authentication component performs the task of checking the users credentials (password). The default action of
this module is to not permit the user access to a service if their official password is blank.
The password component of this module performs the task of updating the user's password. The default encryption hash
is taken from the ENCRYPT_METHOD variable from /etc/login.defs
The session component of this module logs when a user logins or leave the system.
Remaining arguments, supported by others functions of this module, are silently ignored. Other arguments are logged
as errors through syslog(3).
OPTIONS
debug
Turns on debugging via syslog(3).
audit
A little more extreme than debug.
nullok
The default action of this module is to not permit the user access to a service if their official password is
blank. The nullok argument overrides this default and allows any user with a blank password to access the
service.
nullok_secure
The default action of this module is to not permit the user access to a service if their official password is
blank. The nullok_secure argument overrides this default and allows any user with a blank password to access the
service as long as the value of PAM_TTY is set to one of the values found in /etc/securetty.
try_first_pass
Before prompting the user for their password, the module first tries the previous stacked module's password in
case that satisfies this module as well.
use_first_pass
The argument use_first_pass forces the module to use a previous stacked modules password and will never prompt
the user - if no password is available or the password is not appropriate, the user will be denied access.
nodelay
This argument can be used to discourage the authentication component from requesting a delay should the
authentication as a whole fail. The default action is for the module to request a delay-on-failure of the order
of two second.
use_authtok
When password changing enforce the module to set the new password to the one provided by a previously stacked
password module (this is used in the example of the stacking of the pam_cracklib module documented below).
not_set_pass
This argument is used to inform the module that it is not to pay attention to/make available the old or new
passwords from/to other (stacked) password modules.
nis
NIS RPC is used for setting new passwords.
remember=n
The last n passwords for each user are saved in /etc/security/opasswd in order to force password change history
and keep the user from alternating between the same password too frequently. Instead of this option the
pam_pwhistory module should be used.
shadow
Try to maintain a shadow based system.
md5
When a user changes their password next, encrypt it with the MD5 algorithm.
bigcrypt
When a user changes their password next, encrypt it with the DEC C2 algorithm.
sha256
When a user changes their password next, encrypt it with the SHA256 algorithm. If the SHA256 algorithm is not
known to the crypt(3) function, fall back to MD5.
sha512
When a user changes their password next, encrypt it with the SHA512 algorithm. If the SHA512 algorithm is not
known to the crypt(3) function, fall back to MD5.
blowfish
When a user changes their password next, encrypt it with the blowfish algorithm. If the blowfish algorithm is not
known to the crypt(3) function, fall back to MD5.
rounds=n
Set the optional number of rounds of the SHA256, SHA512 and blowfish password hashing algorithms to n.
broken_shadow
Ignore errors reading shadow information for users in the account management module.
minlen=n
Set a minimum password length of n characters. The default value is 6. The maximum for DES crypt-based passwords
is 8 characters.
obscure
Enable some extra checks on password strength. These checks are based on the "obscure" checks in the original
shadow package. The behavior is similar to the pam_cracklib module, but for non-dictionary-based checks. The
following checks are implemented:
Palindrome
Verifies that the new password is not a palindrome of (i.e., the reverse of) the previous one.
Case Change Only
Verifies that the new password isn't the same as the old one with a change of case.
Similar
Verifies that the new password isn't too much like the previous one.
Simple
Is the new password too simple? This is based on the length of the password and the number of different types
of characters (alpha, numeric, etc.) used.
Rotated
Is the new password a rotated version of the old password? (E.g., "billy" and "illyb")
Invalid arguments are logged with syslog(3).
MODULE TYPES PROVIDED
All module types (account, auth, password and session) are provided.
RETURN VALUES
PAM_IGNORE
Ignore this module.
EXAMPLES
An example usage for /etc/pam.d/common-password might be:
password [success=2 default=ignore] pam_extrausers.so obscure sha512
password [success=1 default=ignore] pam_unix.so obscure sha512
# here's the fallback if no module succeeds
password requisite pam_deny.so
# prime the stack with a positive return value if there isn't one already;
# this avoids us returning an error just because nothing sets a success code
# since the modules above will each just jump around
password required pam_permit.so
# and here are more per-package modules (the "Additional" block)
password optional pam_gnome_keyring.so
password optional pam_ecryptfs.so
SEE ALSO
login.defs(5), pam.conf(5), pam.d(5), pam(7)
AUTHOR
pam_extrausers was written by various people.
[FIXME: source] 07/16/2026 PAM_EXTRAUSERS(8)