PAM_PASSWDQC(8)                                    BSD System Manager's Manual                                   PAM_PASSWDQC(8)

NAME
     pam_passwdqc -- Password quality-control PAM module

SYNOPSIS
     [service-name] module-type control-flag pam_passwdqc [options]

DESCRIPTION
     The pam_passwdqc module is a simple password strength checking module for PAM.  In addition to checking regular passwords,
     it offers support for passphrases and can provide randomly generated ones.

     The pam_passwdqc module provides functionality for only one PAM management group: password changing.  In terms of the
     module-type parameter, this is the ``password'' feature.

     The pam_chauthtok() service function may ask the user for a new password, and verify that it meets certain minimum stan-
     dards.  If the chosen password is unsatisfactory, the service function returns PAM_AUTHTOK_ERR.

     The following options may be passed to the module:

     min=N0,N1,N2,N3,N4
             (min=disabled,24,11,8,7) The minimum allowed password lengths for different kinds of passwords/passphrases.  The
             keyword disabled can be used to disallow passwords of a given kind regardless of their length.  Each subsequent
             number is required to be no larger than the preceding one.

             N0 is used for passwords consisting of characters from one character class only.  The character classes are: dig-
             its, lower-case letters, upper-case letters, and other characters.  There is also a special class for non-ASCII
             characters, which could not be classified, but are assumed to be non-digits.

             N1 is used for passwords consisting of characters from two character classes that do not meet the requirements for
             a passphrase.

             N2 is used for passphrases.  Note that besides meeting this length requirement, a passphrase must also consist of a
             sufficient number of words (see the passphrase option below).

             N3 and N4 are used for passwords consisting of characters from three and four character classes, respectively.

             When calculating the number of character classes, upper-case letters used as the first character and digits used as
             the last character of a password are not counted.

             In addition to being sufficiently long, passwords are required to contain enough different characters for the char-
             acter classes and the minimum length they have been checked against.

     max=N   (max=40) The maximum allowed password length.  This can be used to prevent users from setting passwords that may be
             too long for some system services.  The value 8 is treated specially: if max is set to 8, passwords longer than 8
             characters will not be rejected, but will be truncated to 8 characters for the strength checks and the user will be
             warned.  This is to be used with the traditional DES-based password hashes, which truncate the password at 8 char-
             acters.

             It is important that you do set max=8 if you are using the traditional hashes, or some weak passwords will pass the
             checks.

     passphrase=N
             (passphrase=3) The number of words required for a passphrase, or 0 to disable the support for user-chosen
             passphrases.

     match=N
             (match=4) The length of common substring required to conclude that a password is at least partially based on infor-
             mation found in a character string, or 0 to disable the substring search.  Note that the password will not be
             rejected once a weak substring is found; it will instead be subjected to the usual strength requirements with the
             weak substring removed.

             The substring search is case-insensitive and is able to detect and remove a common substring spelled backwards.

     similar=permit|deny
             (similar=deny) Whether a new password is allowed to be similar to the old one.  The passwords are considered to be
             similar when there is a sufficiently long common substring and the new password with the substring removed would be
             weak.

     random=N[,only]
             (random=42) The size of randomly-generated passphrases in bits (24 to 72), or 0 to disable this feature.  Any
             passphrase that contains the offered randomly-generated string will be allowed regardless of other possible
             restrictions.

             The only modifier can be used to disallow user-chosen passwords.

     enforce=none|users|everyone
             (enforce=everyone) The module can be configured to warn of weak passwords only, but not actually enforce strong
             passwords.  The users setting will enforce strong passwords for invocations by non-root users only.

     non-unix
             Normally, pam_passwdqc uses getpwnam(3) to obtain the user's personal login information and use that during the
             password strength checks.  This behavior can be disabled with the non-unix option.

     retry=N
             (retry=3) The number of times the module will ask for a new password if the user fails to provide a sufficiently
             strong password and enter it twice the first time.

     ask_oldauthtok[=update]
             Ask for the old password as well.  Normally, pam_passwdqc leaves this task for subsequent modules.  With no argu-
             ment, the ask_oldauthtok option will cause pam_passwdqc to ask for the old password during the preliminary check
             phase.  If the ask_oldauthtok option is specified with the update argument, pam_passwdqc will do that during the
             update phase.

     check_oldauthtok
             This tells pam_passwdqc to validate the old password before giving a new password prompt.  Normally, this task is
             left for subsequent modules.

             The primary use for this option is when ask_oldauthtok=update is also specified, in which case no other module gets
             a chance to ask for and validate the password.  Of course, this will only work with UNIX passwords.

     use_first_pass, use_authtok
             Use the new password obtained by modules stacked before pam_passwdqc.  This disables user interaction within
             pam_passwdqc.  The only difference between use_first_pass and use_authtok is that the former is incompatible with
             ask_oldauthtok.

SEE ALSO
     getpwnam(3), pam.conf(5), pam(8)

AUTHORS
     The pam_passwdqc module was written for Openwall GNU/*/Linux by Solar Designer <solar at openwall.com>.  This manual page,
     derived from the author's documentation, was written for the FreeBSD Project by ThinkSec AS and NAI Labs, the Security
     Research Division of Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 (``CBOSS''), as part of the
     DARPA CHATS research program.

BSD                                                     February 12, 2008                                                    BSD