Man page 8 : pam_pwhistory

pam_pwhistory - PAM module to remember last passwords

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

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.

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=\fBN\fR
    The last N passwords for each user are saved in /etc/security/opasswd. The default is 10.

retry=\fBN\fR
    Prompt user at most N times before returning with error. The default is 1.

authtok_type=\fBSTRING\fR
    See pam_get_authtok(3) for more details.

Only the password module type is provided.

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.

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

.

/etc/security/opasswd
    File with password history

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

pam_pwhistory was written by Thorsten Kukuk <>