[Oisf-users] number of alerts versus performance

Thu Jul 7 01:07:10 UTC 2016

I tried using top with "H". I have 4 threads running under suricata. One of them peaks at 100% while others are at 50% or so. On occasion different thread gets 100%. Packet loss occurs on the thread which has 100% utilization. I am not sure why these are not spread out evenly.

________________________________
From: Oisf-users <oisf-users-bounces at lists.openinfosecfoundation.org> on behalf of Andreas Herz <andi at geekosphere.org>
Sent: Wednesday, July 6, 2016 8:12 PM
To: oisf-users at lists.openinfosecfoundation.org
Subject: Re: [Oisf-users] number of alerts versus performance

On 06/07/16 at 11:06, Yasha Zislin wrote:
> Sure. Home nets are nothing special.
>
> 123.123.64.0/18,123.123.128.0/18

Well that shouldn't be an issue unless there is a strange bug :)

>
> Is there a way to find out which process in Suricata is eating up the CPU? Maybe that's how I can trace it down to what is causing dramatic packet loss.

You can use top, htop and perf top.
In top use "H" for example

>
> Thank you all.
>
>
> ________________________________
> From: Oisf-users <oisf-users-bounces at lists.openinfosecfoundation.org> on behalf of Andreas Herz <andi at geekosphere.org>
> Sent: Tuesday, July 5, 2016 8:20 PM
> To: oisf-users at lists.openinfosecfoundation.org
> Subject: Re: [Oisf-users] number of alerts versus performance
>
> On 01/07/16 at 14:03, Yasha Zislin wrote:
> > My guess would be that the packet loss is due to the traffic type and
> > home_net definition. This sensor is in management zone so it has a lot
> > of Active Directory, SSH, RDP, and other management traffic. I dont
> > know if this can have a negative impact on performance.
>
> Can you share your HOME_NET definition (with example IPs)?
> So far we can just guess :)
>
> >
> > For example, I have another sensor which mostly processes HTTP/S and
> > SQL/Oracle traffic with 50mil packets a minute and it only has couple
> > of % of packet loss. Sam physical server with the same suricata config
> > with the exception of HOME_NET
> >
> >
> > ________________________________ From: Peter Manev
> > <petermanev at gmail.com> Sent: Thursday, June 30, 2016 9:57 PM To: Yasha
> > Zislin Cc: oisf-users at lists.openinfosecfoundation.org Subject: Re:
> > [Oisf-users] number of alerts versus performance
> >
> > On Thu, 2016-06-30 at 17:14 +0000, Yasha Zislin wrote:
> > > More info. It seems my threads process different amount of packets.
> > > It is not evenly distributed. Is there a setting somewhere for that
> > > in Suricata or in PFRING? It seems that thread with 100% cpu
> > > utilization changes from one to another over time. At that time I
> > > notice from stats.log that new busy thread is processing more
> > > packets.
> > >
> >
> > You mentioned earlier you were messing around with a number of diff
> > settings - might be related. Did you use the irq affinity script (if
> > you got an Intel nic)?
> >
> > >
> > >
> > >
> > > ______________________________________________________________________
> > > From: Peter Manev <petermanev at gmail.com> Sent: Thursday, June 30,
> > > 2016 4:27 PM To: Yasha Zislin Cc:
> > > oisf-users at lists.openinfosecfoundation.org Subject: Re: [Oisf-users]
> > > number of alerts versus performance
> > >
> > > On Thu, 2016-06-30 at 15:54 +0000, Yasha Zislin wrote:
> > > > Peter,
> > > >
> > > >
> > > > I found one alert that was causing high alert count. After I've
> > > > disabled it, count went down but packet loss is still around 20%.
> > > >
> > > >
> > > > my stats.log does not contain anything useful such as flow
> > > > emergency mode, or ssn memcap drop. The only thing that is off is
> > > > kernel
> > > drops,
> > > > and tcp reassembly gaps.  From my understanding kernel drops have
> > > > nothing to do with Suricata and point to OS problems.
> > > >
> > > >
> > > > I do see one of the CPUs peak at 100% when packet loss increases.
> > > One
> > > > thing to note. Two other CPUs are working on capturing traffic
> > > > with high IRQs. My guess would be flow manager or detection
> > > > engine.
> > > >
> > >
> > >
> > > You can see if you get more info from: top -H -p `pidof suricata`
> > > and perf top -c cpu_number_here example: perf top -c 0
> > >
> > > > I dunno.
> > > >
> > > >
> > > > Thanks
> > > >
> > > >
> > > >
> > > >
> > > >
> > > ______________________________________________________________________
> > > > From: Peter Manev <petermanev at gmail.com> Sent: Thursday, June 30,
> > > > 2016 3:00 PM To: Yasha Zislin Cc:
> > > > oisf-users at lists.openinfosecfoundation.org Subject: Re:
> > > > [Oisf-users] number of alerts versus performance
> > > >
> > > > On Thu, 2016-06-30 at 14:41 +0000, Yasha Zislin wrote:
> > > > > I have been trying to figure out a packet loss on one of my
> > > sensors
> > > > > and I am puzzled.
> > > > >
> > > > > It is has 16 gigs of RAM, one quad core AMD CPU, and nic sees
> > > about
> > > > 3
> > > > > million packets per minute. Nothing special in my mind. I am
> > > > > using PFRING 6.5.0 and Suricata 3.1.
> > > > >
> > > > > I get about 20% to 40% packet loss.  I have another identical
> > > server
> > > > > which sees the same amount of traffic and maybe some of the same
> > > > > traffic as well.
> > > > >
> > > > > I've been messing around with NIC settings, IRQs, PFRING
> > > > > settings, Suricata settings trying to figure out why such a high
> > > > > packet
> > > loss.
> > > > >
> > > > >
> > > > > I have just realized one big difference in these two sensors.
> > > > > Problematic one gets 2k to 4k of alerts per minute which sounds
> > > > huge.
> > > > >
> > > >
> > > > Any particular sig that is alerting in excess ?
> > > >
> > > > > Second one gets like 80 alerts per minute. Both have the same
> > > > > rulesets.
> > > > >
> > > > >
> > > > > The difference of course is the home_net variable.
> > > > >
> > > > >
> > > > > Can the fact that Suricata processes more rules due to HOME_NET
> > > > > definition cause high performance strain on the server?
> > > > >
> > > >
> > > > Yes HOME_NET size has effect on performance as well (among other
> > > > things). For example - HOME_NET: "any" EXTERNAL_NET: "any" will
> > > > certainly degrade your performance.
> > > >
> > > > >
> > > > > If the packet does not match per HOME_NET, it will be discarded
> > > > before
> > > > > being processed in rules. Correct?
> > > > >
> > > > > Versus if packet passes HOME_NET check, it would have to go
> > > through
> > > > > all of the rules, hence cause higher CPU utilization.
> > > > >
> > > > >
> > > > > Thank you for the clarification.
> > > > >
> > > > >
> > > > > _______________________________________________ Suricata IDS
> > > > > Users mailing list:
> > > > oisf-users at openinfosecfoundation.org
> > > > > Site: http://suricata-ids.org | Support:
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Open Source IDS / IPS / NSM engine

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> >
> >
> >
> > >
> > >
> > > Suricata suricata-ids.org Open Source IDS / IPS / NSM engine
> > >
> > >
> > > > http://suricata-ids.org/support/
> > > >
> > > >
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> > > >
> > > >
> > > > > List:
> > > > https://lists.openinfosecfoundation.org/mailman/listinfo/oisf-users
> > > > > Suricata User Conference November 9-11 in Washington, DC:
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> > > >
> > > >
> > >
> > >
> >
> > -- Regards, Peter Manev
> >
>
> > _______________________________________________
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> > Site: http://suricata-ids.org | Support: http://suricata-ids.org/support/
> > List: https://lists.openinfosecfoundation.org/mailman/listinfo/oisf-users
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>
>
> --
> Andreas Herz
> _______________________________________________
> Suricata IDS Users mailing list: oisf-users at openinfosecfoundation.org
> Site: http://suricata-ids.org | Support: http://suricata-ids.org/support/
> List: https://lists.openinfosecfoundation.org/mailman/listinfo/oisf-users
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--
Andreas Herz
_______________________________________________
Suricata IDS Users mailing list: oisf-users at openinfosecfoundation.org
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