Firewalls have become a surprisingly disregarded part of enterprise security. Every enterprise has anything from dozens to hundreds of them and yet they are often only noticed when something is going wrong. Arguably, their success has also moved the problem to other parts of the stack such as users and applications which explains why firewall products have expanded their reach to encompass so many new features.
As firewalls have become more and more complex, management has turned from inconvenience to risk. This is the crux of the challenge they create. They need constant adjustment, tending and management. A firewall is never right or if it is, that doesn’t apply for very long.