HP-UX 11i December 2002 Release Notes

Security
Password History Feature on Trusted Systems
Chapter 13
258
Password History Feature on Trusted Systems
Password history is a new trusted-system feature of the passwd command, used to
discourage users from re-using previously used passwords.
The system administrator enables the system-wide password history feature by creating
(or opening, if it already exists) a file called /etc/default/security and appending an
entry:
PASSWORD_HISTORY_DEPTH=number
Depending on the value of number (decimal integer from 1 through 10), the system
checks the user’s new password against that number of previously used passwords and
prevents their usage. (For example, if number=5, the system will not allow a user to use
any of the last five passwords he or she has previously used.)
Structurally, the password history feature is accomplished by a shared library, called
libpam_unix.1, which is dynamically loaded at run time by the command. This
structural characteristic is totally transparent to users; the end-user interface of the
command is unchanged.
For further information, consult the passwd (1) manpage.