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

     pam_passwdqc — Password quality-control PAM module

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

     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 standards.  If the chosen
     password is unsatisfactory, the service function returns PAM_AUTHTOK_ERR.

     The following options may be passed to the module:

             (min=disabled,24,12,8,7) 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: digits, 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 which do not meet the requirements for a

             N2 is used for passphrases.  A passphrase must consist of
             sufficient 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 character 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 which 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 characters.

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

             (match=4) The length of common substring required to conclude
             that a password is at least partially based on information 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=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=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=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.

             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

             (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 for the old password as well.  Normally, pam_passwdqc leaves
             this task for subsequent modules.  With no argument, 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.

             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

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

     The pam_passwdqc module was written for Openwall GNU/*/Linux by Solar
     Designer <solar at>.  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                            January 26, 2005                            BSD