• Configuration errors—Misconfigured firewalls may allow unknown and dangerous services to pass through freely.
• Monitoring demands—It is necessary to apply and review log settings appropriately, but monitoring activities may
not always occur on a regular basis.
• Policy maintenance—Firewall policies may not be maintained regularly.
• Vulnerability to application- and input-based attacks—Most firewalls operate at the network layer; therefore,
they do not stop any application-based or input-based attacks, such as SQL injection and buffer-overflow attacks.
Newer-generation firewalls are able to inspect traffic at the application layer and stop some of these attacks