[Oisf-users] hardware timestamping with af-packet/suricata

Michał Purzyński michalpurzynski1 at gmail.com
Sun Nov 13 19:10:34 UTC 2016

Given how the hardware timestamps are sometimes constructed, I'd say, let's give users a choice 

> On 13 Nov 2016, at 13:44, jason taylor <jtfas90 at gmail.com> wrote:
> Hi Michal,
> I have not opened a ticket yet. I wanted to make sure this wasn't an
> edge case type request/situation before I opened one.
> JT
>> On Sun, 2016-11-13 at 13:06 -0500, Michał Purzyński wrote:
>> We should, by all means, support a choice here and give users an
>> option what they want to do. I'm filing a similar bug for bro now.
>> Have you opened Suricata by already?
>>> On 11 Nov 2016, at 11:31, jason taylor <jtfas90 at gmail.com> wrote:
>>> After talking with Victor a little bit at the conference he
>>> suggested
>>> seeing what others have to say.
>>> In our environment we recently discovered an issue related to
>>> hardware
>>> timestamping. 
>>> After a period of time post NIC driver load, we will see a drift
>>> forward and/or back in time. The forward or back is depedant on the
>>> frequency of the chip on the NIC. In our case we have 10g and 40g
>>> cards
>>> we see the issue with. This results in our suricata alerts being
>>> stamped with the errant time since suricata/af-packet uses hardware
>>> timestamping if it's available.
>>> Looking into possible solutions while waiting on a response from
>>> the
>>> vendor I noted that netsniff-ng also by default uses hardware
>>> timestamping but added a --no-hwtimestamp runtime option to account
>>> for
>>> situations where hardware timestamping is buggy or what have you.
>>> While realizing this isn't a suricata issue, (we should have chosen
>>> our
>>> hardware a bit more carefully). Aside from hardware/driver issues
>>> are
>>> there other situations where one might want to disable hardware
>>> timestamping at runtime (.e.g. --no-hwtimestamp) in suricata? Is
>>> this
>>> something that would be worth adding as a configuration option in
>>> suricata?
>>> TIA,
>>> JT
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>>> rg
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>>> -users
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