Amanda is worried about LDAP injection attacks against her directory server. What is NOT a common technique to prevent LDAP injection attacks?

Output filtering rules are not a common technique to prevent LDAP injection attacks. LDAP injection attacks exploit vulnerabilities in applications that do not properly sanitize user input before using it in LDAP queries. Output filtering rules can be used to prevent certain types of attacks, such as cross-site scripting (XSS), but they are not effective against LDAP injection attacks.