pam_pwcheck - PAM module for password strength checking


The pam_pwcheck is a PAM module for password strength checking. It makes additional checks upon password changes, but does not perform the change itself. It only provides functionality for one PAM management group: password changing.

This module works in the following manner: if enabled, it first calls the Cracklib routine to check the strength of the password; if crack likes the password, the module does an additional set of strength checks. These checks are:
 Is the new password a palindrome of the old one?
Case Change Only
 Is the new password the old one with only a change of case?
 Is the new password too similar to old one?
Simple Is the new password too short?
 Is the new password a rotated version of the old password?
Already used
 Was the password used in the past? Previously used passwords are to be found in /etc/security/opasswd.


The following options may be passed to the module:
cracklib=<path to dictionaries>
 Use cracklib library for password checks. This parameter also contains the path to the cracklib dictionaries. The default is /usr/lib/cracklib_dict.
debug A lot of debug information is printed with syslog(3).
 Number of significant characters in the password for crypt(3). A value of zero suppresses this check. The default is 0.
 The minimum number of characters in an acceptable password. A new password with fewer characters will be rejected. A value of zero suppresses this check. The default is 5.
 No additional checks will be performed before a new password is accepted. Since the checks performed are fairly simple, their usage is recommended.
 If this option is given, pam_pwcheck will not make the new password available for other modules.
nullok Normally the account is disabled if no password is set or if the length of the password is zero. With this option you can allow the user to change his password for such accounts. This option does not overwrite a hardcoded default by the calling process.
 Maximum number of attempts to change a password if the new ones are rejected because they are too easy.
 Set the new password to the one provided by the previously stacked password module. If this option is not set, pam_pwcheck will ask the user for the new password.
 By default pam_pwcheck tries to get the authentication token from a previous module. If no token is available, the user is asked for the old password. With this option, pam_pwcheck aborts with an error if no authentication token from a previous module is available.
 Remember the last XX passwords and do not allow the user to reuse any of these for the next XX password changes. XX is a number between 1 and 400.
 If this option is set, most of the password check rules are enforced for root, too. Never use this option if you don’t know what you are doing, since it could be as result that root is no longer allowed to login at all.




passwd(1), pam.conf(8), pam.d(8), pam(8), rpasswd(1), rpasswdd(8), rpc.yppasswdd(8), yppasswd(1)

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