The SLES for vRealize must require the change of at least eight of the total number of characters when passwords are changed.
If the operating system allows the user to consecutively reuse extensive portions of passwords, this increases the chances of password compromise by increasing the window of opportunity for attempts at guessing and brute-force attacks.
The number of changed characters refers to the number of changes required with respect to the total number of positions in the current password. In other words, characters may be the same within the two passwords; however, the positions of the like characters must be different.
The "difok" parameter indicates how many characters must be different. The DoD requires at least eight characters to be different during a password change. This would appear as "difok=8". If difok is not found or not set to at least "8", this is a finding.