Help With Traffic Hitting Implicit Deny

[NoneEng]

Hello,

I have some traffic hitting Implicit Deny, even tho the Allow Policy seems to be correct:

Logs:

Rule:

 

Found this: Traffic dropped by 'implicit deny pol... - Fortinet Community, but everything shown is ok here.

This might be relevant: I recently changed my FortiGate from standalone to Fabric Root.

Could you please help diagnose this? Thanks in advance.

[AEK]

Hi

Try check in quarantine monitor if the spurce IP addresses are not quarantined.

Also check in the above log if the outgoing interface is the right one in the policy.

[NoneEng]

Hi @AEK!

No quarantined IP or devices.

In the logs the outgoing interface is the right one.

One thing I noticed is the blocks happen only with my WLANs.

Created a new Policy "TEMP_TEST", added it on the top with one of them:

Logs:

PS: This WLAN has a captive portal and is from a FortiAP. Users just need to accept the terms to login in.

I don't have a clue :grinning_face_with_sweat:
Any ideas how to further look into it?

[AEK]

Hi NoneEng

So can you disable the active portal and try again?

[NoneEng]

Hey @AEK , sorry for my absence.

I would still need to enable other type of security auth:

[AEK]

I mean disable it temporarily just to make sure it is (or it is not) the root cause.

[rahul_p1]

Hi,

Please share the debug logs:-

diagnose debug reset
diagnose debug flow trace stop
diagnose debug flow filter clear
diagnose debug flow filter addr X.X.X.X   -------->>x.x.x.x is your destination IP
diagnose debug flow show function-name enable
diagnose debug console timestamp enable
diagnose debug flow trace start 1000
diagnose debug enable

Note:- Run this to stop the debug

diagnose debug disable 

[vbandha]

Hello @NoneEng 

Can you check if there is appropriate SD WAN rule enabled for this?

It is most likely a routing issue, the debug flow mentioned earlier will give more information about what is happening. 

One other thing you could try as a troubleshooting step is to create policy route for this traffic specifically:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Configuring-the-Firewall-Policy-Routes/ta-...

Regards,

Varun

[sahmed_FTNT]

Hello, you can verify below settings:

-correct source

-service(ports) are allowed

-correct interface

- there is no deny policy at top of allow policy

also make sure in policy schedule portion it has correct values