Edit: /usr/share/doc/pam/txts/README.pam_pwhistory (2243B)
pam_pwhistory -- PAM module to remember last passwords
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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. 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.
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.
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
AUTHOR
pam_pwhistory was written by Thorsten Kukuk