Implicit Deny in FortiGate

[unknown1020]

Good morning friends, could you help me understand the purpose of “Implicit Deny” (ID 0)?
In my FW I have 3 DENY policies: 2 Policies so that attacking IPs do not communicate with my internal network and the other policy is the “Implicit Deny” (ID 0).
Can you clarify for me about the behavior of “Implicit Deny”, I would understand that if it does not trigger any rule prior to it, by default, Deny would be given to everything. So it wouldn't be necessary to create other DENY rules?

[RileyKyrie]

I've configured a set of specific DENY policies to block traffic from certain IP addresses that are known to be malicious or potentially harmful to my network. Having these DENY policies in place, I've noticed that some of this unwanted traffic is still managing to slip through and access my andok's liempo price site. Upon reviewing the firewall logs, I can see that the traffic is indeed hitting the DENY policies.

[Junny43]

The "Implicit Deny" policy, typically represented by ID 0 in FortiGate firewalls, serves as a default rule that denies any traffic that does not match any of the explicitly defined allow or deny rules above it. Essentially, if incoming traffic does not meet the criteria specified in any preceding rule, it will be implicitly denied by this default rule.

The purpose of having an "Implicit Deny" policy is to ensure that no unauthorized traffic can pass through the firewall by default. It acts as a safety net, preventing any traffic from slipping through unnoticed if it doesn't match any explicitly configured rules.

While the "Implicit Deny" policy provides a blanket denial for unmatched traffic, it's still important to have specific deny rules for certain scenarios. These rules allow you to explicitly block traffic that you know should not be allowed, providing granular control over your network security.

In your case, having specific deny policies for blocking attacking IPs ensures that known threats are blocked preemptively. However, the "Implicit Deny" policy ensures that any traffic not covered by these specific deny rules is still denied by default, adding an extra layer of security to your firewall configuration.

[Junny43]

The "Implicit Deny" (ID 0) policy in FortiGate is a default deny policy that is implicitly applied at the end of the firewall policy list. Its purpose is to ensure that any traffic that doesn't match any of the previous policies is denied by default, providing an additional layer of security. For more information about this Bus Simulator Indonesia Mod APK for iPhone. Click on this link.

In your case, having two explicit DENY policies for specific attacking IPs and the Implicit Deny policy (ID 0) at the end, ensures that any other unwanted traffic that doesn't match the first two policies will be denied by the Implicit Deny policy. This means you're correct that it's not strictly necessary to create additional DENY rules, as the Implicit Deny policy will catch any traffic that falls through the cracks. However, having explicit DENY policies for specific threats can provide more targeted control and logging capabilities, making it a good practice to have both in place.