pam_extrausers — Module for libnss-extrausers authentication

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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).

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


AUTHOR

pam_extrausers was written by various people.

