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pam_pwcheck

NAME

pam_pwcheck - PAM module for password strength checking

DESCRIPTION

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:

Palindrome

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?

Similar

Is the new password too similar to old one?

Simple

Is the new password too short?

Rotated

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.

OPTIONS

The following options may be passed to the module:

blowfish

This is a password encryption method used by OpenBSD and the Openwall Linux distribution. This option allows for passwords of up to 97 characters. Longer passwords will be truncated. The encryption itself is done by the PAM module which stores the password.

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).

maxlen=number

Number of significant characters in the password for crypt(3). Default is 8, don't change this unless your crypt() is better. This option is ignored if the "md5" or "blowfish" option is given.

minlen=number

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.

nisdir=<path>

This option specifies a path to the source files for NIS maps on a NIS master server. If this option is given, the passwords of NIS accounts will not be changed with yppasswd(1), instead the local passwd and shadow files below <path> will be modified. In conjunction with rpasswdd(8) and pam_make you can replace rpc.yppasswdd(8) with a more secure solution on the NIS master server.

no_obscure_checks

No additional checks will be performed before a new password is accepted. Since the checks performed are fairly simple, their usage is recommended.

not_set_pass

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.

tries=number

Maximum number of attempts to change a password if the new ones are rejected because they are too easy.

use_authtok

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.

use_first_pass

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.

md5

In the case of conventional unix databases (which store the password encrypted) the md5 argument is used to do the encryption with the MD5 function as opposed to the conventional crypt(3) call.

bigcrypt

As an alternative to md5, the bigcrypt argument can be used to encrypt more than the first 8 characters of a password with DEC's (Digital Equipment Cooperation) `C2' extension to the standard UNIX crypt() algorithm.

remember=XX

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.

enforce_for_root

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.

FILES

/etc/security/opasswd

SEE ALSO

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