Many clients use a combination of traditional perimeter security technologies like Firewalls and default public cloud security settings like ACL’s when designing and deploying applications. The focus is normally on public-facing web assets. This increasing sophistication of attacks means that these methods are no longer effective, and a new approach is required. The sheer scale IPv6 makes blacklisting of IP’s totally ineffective.
In summary: Old approaches aren’t as effective anymore, start with “Deny All” and whitelist only required services.
Look at whitelisting tools like Airlock and Applocker from Microsoft.