[Snort-users] 2.1.3rc1 Performance

John Creegan jcreegan at ...9729...
Wed May 19 14:39:01 EDT 2004

I think you might be able to kill or launch multiple instances if you create a shellscript to kill or launch each instance (you'd have to know the PID of each) and use cron to call the kill or launch scripts.  It might not be down to the nanosecond, but it'll be darn close.

Make sure two specify two separate cron table entries to do this, both with the same date/time spec.  Chaining the two events together on one line with a semicolon would defeat the purpose.

>>> <Gary_Portnoy at ...11307...> 05/19/04 03:38PM >>>
netstat -ni reports all the packets since the last reboot, not really 
Running two instances side by side doesn't really work since i can't 
launch them both or kill them both at exactly the same time.

The only way to verify that would be to inject a known amount of packets 
on the wire and see which version reports the correct value.  Can anyon 
recommend a tool for packet generation?  I am thinking I'd like to create 
like 400,000 packets and inject them on the wire at 5mbps and see which 
version reports the truth.

Gary Portnoy

Dirk Geschke <Dirk at ...10648...>
05/19/2004 03:47 PM

        To:     Gary_Portnoy at ...11307... 
        cc:     snort-users at lists.sourceforge.net 
        Subject:        RE: [Snort-users] 2.1.3rc1 Performance

Hi Gary,

> The question remains however, which version is misreporting statistics? 
> suspect 0.8.3 since it reported 128.633% drop rate at one point.

hmm, drop/(recv+drop) shoule never exceed 100% or recv must be 

> Or is 0.8.3 just that much slower? 
> Anyone care to comment?

Can you verify how many packets were really on the wire
during your snort runs?

I think 'netstat -ni' should be helpful or a parallel snoop run 
on the sniffed interface. Maybe the old libpcap returned wrong

Best regards


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