The system must require at least four characters be changed between the old and new passwords during a password change.

From Red Hat Enterprise Linux 5 Security Technical Implementation Guide

Associated with IA controls: IAIA-2, IAIA-1

Associated with: CCI-000195

SV-37304r1_rule The system must require at least four characters be changed between the old and new passwords during a password change.

Vulnerability discussion

To ensure password changes are effective in their goals, the system must ensure that old and new passwords have significant differences. Without significant changes, new passwords may be easily guessed based on the value of a previously compromised password.

Check content

Fix text

If /etc/pam.d/system-auth references /etc/pam.d/system-auth-ac refer to the man page for system-auth-ac for a description of how to add options not configurable with authconfig. Edit /etc/pam.d/system-auth and add or edit a pam_cracklib entry with an difok parameter set equal to or greater than 4.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.