Why did FortiGate drop a particular packet?

The selection of the option regarding the default implicit firewall policy highlights a fundamental aspect of how FortiGate processes packets within its security framework. In FortiGate, an implicit policy is established by default that serves as a baseline for traffic management and security. This policy dictates the handling of packets that do not explicitly match any user-defined firewall rules.

When a packet arrives at the FortiGate and does not satisfy any of the configured policies, it will typically match the default implicit policy, which, in many configurations, will result in the packet being dropped. This safeguard is paramount as it enhances the security posture by ensuring that any traffic outside of established rules is not inadvertently allowed through, which could lead to potential vulnerabilities or unwanted access.

The other scenarios, while relevant to packet handling in different contexts, do not directly address the behavior dictated by the implicit policies. For instance, suspicious traffic may indeed be dropped based on security protocols, but this is separate from the specific functionality of the implicit policy. Similarly, incorrectly formatted packets might be rejected due to format-related issues, and broadcast packets might be managed differently based on the network configuration and requirements. However, the presence of an implicit policy that governs drops based on rule matching is a core aspect of FortiGate's