Re: Intel X520 and Multi-Queue Snort

[beenph <beenph () gmail com>]

On Fri, May 13, 2011 at 11:56 AM, Martin Holste <mcholste () gmail com> wrote:
> > 16!??!  I currently monitor a link that has a daily peak of about 1.5
> > gigabits per second of actual traffic with 4 snort-processes, and I run
> > about 7000 rules selected from VRT and ET with close to zero
> > packet-loss.
>
> Ha, that's what I thought until a few months ago.  Then I started
> running heartbeat signatures and found out just how much packet drop
> stats lie (from all sources, really).  I outlined basics on how to do
> this on my last blog post at ossectools.blogspot.com.  In addition to
> performance validation, heartbeat sigs are also a great method for
> hooking Snort up to Nagios (or whatever monitoring setup you're using)
> to verify that the entire alert reporting chain is working (i.e.
> Nagios alert if you haven't seen the heartbeat).

I honestly still think that a "heartbeat" signature is not a real solution.
If you are trying to monitor link activty for some behavior, you would need to
wrap code arround your daq module that would generate an event (not a signature)
when there is an issue and pass it down to the desired output module, from there
you would have "real" diagnostic of whats happening.

For example, if someone pull's the wire from your monitoring station
and plug it back
10 minutes later, the only thing you would know is that mabey you
missed one of your heartbeat signature
and if your heartbeat signature passed right before that, then you
would think everything was all right when it fact
you where not monitoring for 10 minutes.

It could also be an issue more upstream like your trunk that get's
disconnected etc etc. And those wouldn't add up in the
"droped packets" since whats not seen is not counted thus is not missed.


-elz

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