centos man page for pam_pwhistory

PAM_PWHISTORY(8)						 Linux-PAM Manual						  PAM_PWHISTORY(8)

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

SEE ALSO
       pam.conf(5), pam.d(5), pam(8)pam_get_authtok(3)

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

Linux-PAM Manual						    09/19/2013							  PAM_PWHISTORY(8)