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PAM_PWHISTORY

Section: Linux-PAM Manual (8)
Updated: 02/02/2026
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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] [file=/path/filename] [conf=/path/to/config-file]

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_passwdqc 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. 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.

file=/path/filename

: Store password history in file /path/filename rather than the default location. The default location is /etc/security/opasswd.

conf=/path/to/config-file

: Use another configuration file instead of the default /etc/security/pwhistory.conf.

The options for configuring the module behavior are described in the pwhistory.conf(5) manual page. The options specified on the module command line override the values from the configuration file.

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_passwdqc:

#%PAM-1.0
password     required       pam_passwdqc.so    config=/etc/passwdqc.conf
password     required       pam_pwhistory.so   use_authtok
password     required       pam_unix.so        use_authtok

FILES

/etc/security/opasswd

: Default file with password history

/etc/security/pwhistory.conf

: Config file for pam_pwhistory options

/usr/share/pam/security/pwhistory.conf

: Config file for pam_pwhistory options. It will be used if /etc/security/pwhistory.conf does not exist.

AUTHOR

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