*Hi Emanuele,*

*I do confirm this was the same issue. I updated the package and alerts
went away.*


*Many thanks.*

Le lun. 25 mai 2020 à 12:23, Emanuele Faranda <[email protected]> a écrit :

> Hi David,
>
> This should be the same issue experienced by Aaron due to frame padding.
> Please check out the other thread.
>
> Regards,
>
> Emanuele
> On 5/24/20 7:54 PM, David van Ginneken wrote:
>
> Hi Simone,
>
> Thanks for the advice. The --ignore-vlans option seems to help as I do not
> see the duplicates anymore.
> I do have vlans on my network but it is not a problem for me not to have
> this separated in the display.
>
> Now I still get odd alerts about HTTP requests not being answered. I'll
> investigate a bit further but it seems VERY similar to the issue Aaron and
> Emanuele are discussing in parallel.
> And, on top of that, it seems Aaron is also using a Unifi device (not the
> same model but I think the OSes are). Could this be a pointer to the root
> cause of our issues?
>
> Thanks again.
>
>
> Le jeu. 21 mai 2020 à 23:18, Simone Mainardi <[email protected]> a écrit :
>
>> Hi,
>>
>> > On 21 May 2020, at 14:55, David van Ginneken <[email protected]>
>> wrote:
>> >
>> > Hi everyone,
>> >
>> > Starting with ntopng, I have a small issue initially setting it up.
>> >
>> > I use port mirroring on a switch to replicate all ports to port 5 where
>> a dedicated ntopng interface 'listens' (Official package on raspbian 10).
>> > On that same switch I have my Internet gateway (Unifi USG3P) connected
>> to port 1. This same device also acts as a DHCP/DNS server.
>> >
>> > When mirroring all ports BUT port 1, I receive alerts about thousands
>> of DNS queries not being answered. I did confirm that with a pcap dump.
>>
>> When you monitor just port 1, apart from the DNS queries unanswered
>> alerts, do you get bi-directional traffic if you look at the flows page? Do
>> you see the @1?
>>
>
>> >
>> > So I went and started to mirror port 1 along with others, and the
>> missing traffic (DNS replies) started to be collected.
>> > The issue is that with that configuration, all flows are listed twice
>> in ntop. Internal hosts are showing normally and with "@1" at the end of
>> the hostname.
>>
>> @1 means VLAN=1 so VLAN-tagged packets are received from the mirror port.
>> VLAN depend on your switch configuration. If you can disregard VLANs you
>> can use option --ignore-vlans
>>
>> >
>> > Is there a way for ntop to discard this duplicated traffic in the
>> accounting of ntopng?
>>
>> I am not sure the traffic is duplicated. It could be that ntopng is
>> keeping the two directions of every flow separated due to the VLAN. Let's
>> continue the investigation depending on your responses.
>>
>> Simone
>>
>> >   It makes sense to me that it is detected as a host's traffic will be
>> seen on its own switch port and then in many cases on port 1.
>> >
>> > Many thanks.
>> > _______________________________________________
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>>
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