login.defs --shadow password suite configuration
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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).
The default action is for the module to use the following prompts when requesting passwords: "New UNIX password: " and "Retype UNIX password: ". The default word UNIX can be replaced with this option.
Prompt user at most N times before returning with error. The default is 1
This argument will change the default of 5 for the number of characters in the new password that must not be present in the old password. In addition, if 1/2 of the characters in the new password are different then the new password will be accepted anyway.
How many characters should the password have before difok will be ignored. The default is 23.
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 which is good for a old style UNIX password all of the same type of character but may be too low to exploit the added security of a md5 system. Note that there is a pair of length limits in Cracklib itself, a "way too short" limit of 4 which is hard coded in and a defined limit (6) that will be checked without reference to minlen. If you want to allow passwords as short as 5 characters you should not use this module.
(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.
(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.
(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.
(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.
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.
Path to the cracklib dictionaries.
Path to the cracklib dictionaries.
These checks are:
Is the new password a palindrome of the old one?
Case Change Only
Is the new password the the old one with only a change of case?
Is the new password too much like the old one?
This is primarily controlled by one argument, difok which is a number of characters that if different between the old and new are enough to accept the new password, this defaults to 10 or 1/2 the size of the new password whichever is smaller.
To avoid the lockup associated with trying to change a long and complicated password, difignore is available. This argument can be used to specify the minimum length a new password needs to be before the difok value is ignored. The default value for difignore is 23.
Is the new password too small?
This is controlled by 5 arguments minlen, dcredit, ucredit, lcredit, and ocredit. See the section on the arguments for the details of how these work and there defaults.
Is the new password a rotated version of the old password?
Was the password used in the past?
Previously used passwords are to be found in /etc/security/opasswd.
password requisite pam_cracklib.so try_first_pass retry=3
password required /lib/security/pam_cracklib.so retry=3 type= minlen=8 difok=3 dictpath=/path/to/dict