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PAM_PWHISTORY

Section: Linux\-PAM Manual (8)
Updated: 04/01/2016
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NAME

pam_pwhistory - PAM module to remember last passwords

SYNOPSIS

pam_pwhistory.so [debug] [use_authtok] [enforce_for_root] [remember=N] [retry=N] [authtok_type=STRING]

DESCRIPTION

This module saves the last passwords for each user in order to force password change history and keep the user from alternating between the same password too frequently.

This module does not work together with kerberos. In general, it does not make much sense to use this module in conjunction with NIS or LDAP, since the old passwords are stored on the local machine and are not available on another machine for password history checking.

OPTIONS

debug

: Turns on debugging via syslog(3).

use_authtok

: When password changing enforce the module to use the new password provided by a previously stacked password module (this is used in the example of the stacking of the pam_cracklib module documented below).

enforce_for_root

: If this option is set, the check is enforced for root, too.

remember=N

: The last N passwords for each user are saved in /etc/security/opasswd. The default is 10. Value of 0 makes the module to keep the existing contents of the opasswd file unchanged.

retry=N

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

authtok_type=STRING

: See pam_get_authtok(3) for more details.

MODULE TYPES PROVIDED

Only the password module type is provided.

RETURN VALUES

PAM_AUTHTOK_ERR

: No new password was entered, the user aborted password change or new password couldn't be set.

PAM_IGNORE

: Password history was disabled.

PAM_MAXTRIES

: Password was rejected too often.

PAM_USER_UNKNOWN

: User is not known to system.

EXAMPLES

An example password section would be:

#%PAM-1.0
password     required       pam_pwhistory.so
password     required       pam_unix.so        use_authtok

In combination with pam_cracklib:

#%PAM-1.0
password     required       pam_cracklib.so    retry=3
password     required       pam_pwhistory.so   use_authtok
password     required       pam_unix.so        use_authtok

FILES

/etc/security/opasswd

: File with password history

AUTHOR

pam_pwhistory was written by Thorsten Kukuk <kukuk@thkukuk.de>