Provided by: libpam-pwquality_1.2.3-1ubuntu1_amd64 bug

NAME

       pam_pwquality - PAM module to perform password quality checking

SYNOPSIS

       pam_pwquality.so [...]

DESCRIPTION

       This  module  can  be  plugged  into the password stack of a given service to provide some
       plug-in strength-checking for passwords. The code was  originally  based  on  pam_cracklib
       module and the module is backwards compatible with its options.

       The  action  of  this  module  is to prompt the user for a password and check its strength
       against a system dictionary and a set of rules for identifying poor choices.

       The first action is to prompt for a single password, check its strength and then, if it is
       considered  strong,  prompt  for  the  password a second time (to verify that it was typed
       correctly on the first occasion). All being well, the password is passed on to  subsequent
       modules to be installed as the new authentication token.

       The strength checks works in the following manner: at first the Cracklib routine is called
       to check if the password is part of a dictionary; if this is not the  case  an  additional
       set of strength checks is done. These checks are:

       Palindrome
           Is the new password a palindrome?

       Case Change Only
           Is the new password the the old one with only a change of case?

       Similar
           Is  the  new  password  too much like the old one? This is primarily controlled by one
           argument, difok which  is  a  number  of  character  changes  (inserts,  removals,  or
           replacements)  between  the  old  and  new  password that are enough to accept the new
           password. This defaults to 5 changes.

       Simple
           Is  the  new  password  too  small?  This  is  controlled  by  6   arguments   minlen,
           maxclassrepeat,  dcredit,  ucredit,  lcredit,  and  ocredit.  See  the  section on the
           arguments for the details of how these work and there defaults.

       Rotated
           Is the new password a rotated version of the old password?

       Same consecutive characters
           Optional check for same consecutive characters.

       Too long monotonic character sequence
           Optional check for too long monotonic character sequence.

       Contains user name
           Optional check whether the password contains the user's name in some form.

       These checks are configurable either by use of the module arguments or  by  modifying  the
       /etc/security/pwquality.conf configuration file.

OPTIONS

       debug
           This option makes the module write information to syslog(3) indicating the behavior of
           the module (this option does not write password information to the log file).

       authtok_type=XXX
           The default action is for the module to use  the  following  prompts  when  requesting
           passwords:  "New  UNIX password: " and "Retype UNIX password: ". The example word UNIX
           can be replaced with this option, by default it is empty.

       retry=N
           Prompt user at most N times before returning with error. The default is 1.

       difok=N
           This argument will change the default of 5 for  the  number  of  changes  in  the  new
           password from the old password.

       minlen=N
           The minimum acceptable size for the new password (plus one if credits are not disabled
           which is the default). In addition to the number of characters in  the  new  password,
           credit  (of +1 in length) is given for each different kind of character (other, upper,
           lower and digit). The default for this parameter is 9 . Note that there is a  pair  of
           length  limits  also  in  Cracklib,  which is used for dictionary checking, a "way too
           short" limit of 4 which is hard coded in and a build time defined limit (6) that  will
           be checked without reference to minlen.

       dcredit=N
           (N  >=  0)  This  is the maximum credit for having digits in the new password.  If you
           have less than or N digits, each digit will  count  +1  towards  meeting  the  current
           minlen  value.  The default for dcredit is 1 which is the recommended value for minlen
           less than 10.

           (N < 0) This is the minimum number of digits that must be met for a new password.

       ucredit=N
           (N >= 0) This is the maximum credit for having upper case letters in the new password.
           If  you  have  less  than  or  N  upper case letters each letter will count +1 towards
           meeting the current  minlen  value.  The  default  for  ucredit  is  1  which  is  the
           recommended value for minlen less than 10.

           (N  <  0)  This is the minimum number of upper case letters that must be met for a new
           password.

       lcredit=N
           (N >= 0) This is the maximum credit for having lower case letters in the new password.
           If  you  have  less  than  or  N lower case letters, each letter will count +1 towards
           meeting the current  minlen  value.  The  default  for  lcredit  is  1  which  is  the
           recommended value for minlen less than 10.

           (N  <  0)  This is the minimum number of lower case letters that must be met for a new
           password.

       ocredit=N
           (N >= 0) This is the maximum credit for having other characters in the  new  password.
           If  you  have  less  than  or N other characters, each character will count +1 towards
           meeting the current  minlen  value.  The  default  for  ocredit  is  1  which  is  the
           recommended value for minlen less than 10.

           (N  <  0)  This  is  the minimum number of other characters that must be met for a new
           password.

       minclass=N
           The minimum number of required classes  of  characters  for  the  new  password.   The
           default number is zero. The four classes are digits, upper and lower letters and other
           characters. The difference to the  credit  check  is  that  a  specific  class  if  of
           characters is not required. Instead N out of four of the classes are required.

       maxrepeat=N
           Reject  passwords  which contain more than N same consecutive characters.  The default
           is 0 which means that this check is disabled.

       maxsequence=N
           Reject passwords which contain monotonic  character  sequences  longer  than  N.   The
           default  is  0 which means that this check is disabled.  Examples of such sequence are
           '12345' or 'fedcb'. Note that most such passwords will not pass the  simplicity  check
           unless the sequence is only a minor part of the password.

       maxclassrepeat=N
           Reject  passwords  which contain more than N consecutive characters of the same class.
           The default is 0 which means that this check is disabled.

       gecoscheck=N
           If nonzero, check whether the individual words  longer  than  3  characters  from  the
           passwd  GECOS  field  of the user are contained in the new password.  The default is 0
           which means that this check is disabled.

       badwords=<list of words>
           The words more than 3 characters long from this space separated list are  individually
           searched  for  and  forbidden in the new password.  By default the list is empty which
           means that this check is disabled.

       enforce_for_root
           The module will return error on failed check even if the user changing the password is
           root. This option is off by default which means that just the message about the failed
           check is printed but root can change the password anyway. Note that root is not  asked
           for  an  old  password  so  the  checks  that compare the old and new password are not
           performed.

       local_users_only
           The module will not test the password quality for users that are not  present  in  the
           /etc/passwd  file.  The module still asks for the password so the following modules in
           the stack can use the use_authtok option.  This option is off by default.

       use_authtok
           This argument is used to force the module to not prompt the user for  a  new  password
           but use the one provided by the previously stacked password module.

       dictpath=/path/to/dict
           Path to the cracklib dictionaries.

MODULE TYPES PROVIDED

       Only the password module type is provided.

RETURN VALUES

       PAM_SUCCESS
           The new password passes all checks.

       PAM_AUTHTOK_ERR
           No  new password was entered, the username could not be determined or the new password
           fails the strength checks.

       PAM_AUTHTOK_RECOVERY_ERR
           The old password was not supplied by a previous stacked module or  got  not  requested
           from the user. The first error can happen if use_authtok is specified.

       PAM_SERVICE_ERR
           A internal error occurred.

EXAMPLES

       For  an example of the use of this module, we show how it may be stacked with the password
       component of pam_unix(8)

           #
           # These lines stack two password type modules. In this example the
           # user is given 3 opportunities to enter a strong password. The
           # "use_authtok" argument ensures that the pam_unix module does not
           # prompt for a password, but instead uses the one provided by
           # pam_pwquality.
           #
           passwd  password required       pam_pwquality.so retry=3
           passwd  password required       pam_unix.so use_authtok

       Another example (in the /etc/pam.d/passwd format) is for the case that you want to use md5
       password encryption:

           #%PAM-1.0
           #
           # These lines allow a md5 systems to support passwords of at least 14
           # bytes with extra credit of 2 for digits and 2 for others the new
           # password must have at least three bytes that are not present in the
           # old password
           #
           password  required pam_pwquality.so \
                          difok=3 minlen=15 dcredit= 2 ocredit=2
           password  required pam_unix.so use_authtok nullok md5

       And here is another example in case you donĀ“t want to use credits:

           #%PAM-1.0
           #
           # These lines require the user to select a password with a minimum
           # length of 8 and with at least 1 digit number, 1 upper case letter,
           # and 1 other character
           #
           password  required pam_pwquality.so \
                          dcredit=-1 ucredit=-1 ocredit=-1 lcredit=0 minlen=8
           password  required pam_unix.so use_authtok nullok md5

SEE ALSO

       pwscore(1), pwquality.conf(5), pam_pwquality(8), pam.conf(5), PAM(8)

AUTHORS

       Tomas Mraz <tmraz@redhat.com>
       Original author of pam_cracklib module Cristian Gafton <gafton@redhat.com>