[Snort-users] Snort-Inline, IPTables and Performance

Will Metcalf william.metcalf at ...11827...
Thu Aug 25 06:38:29 EDT 2005

What kind of throughput do you get if you don't QUEUE your data but
just send it through the   firewall or bridge?  I guess what I mean is
do you see the 2.5mbs if you change you QUEUE rules to ACCEPT rules? 
Don't get me wrong the performance of ip_queue stinks.  You have to
perform two context switches for every packet which introduces a lot
of latency.  Dropping from a 2.5mbs to 300k seems a little excessive

If anybody would like to volunteer, I would still like to see some
real performance tests done on snort-inline.  I do all of my
development work on a PIII 450, this should give you some idea of the
resources I have available to me ;-)

I would like to see tests done with some decent server hardware
Operteron or Xeon and a real testing suite like spirents reflector. 
Any takers?



On 8/24/05, Matt Linton <mlinton at ...10499...> wrote:
> Greetings;
> If anyone has the time to chat performance, I'm seeing some quite
> problematic performance throttling when using snort-inline with
> iptables, and I've been able to get much better performance previously
> than this.
> My build is:  Red Hat Workstation 4 (Linux 2.6.9-5ELsmp) on a Dell
> PowerEdge 1650 with dual Broadcom gigabit adapters.  I'm using Snort
> version 2.3.0 and pushing things through a QUEUE iptables directive to
> do inline IPS.
> Without the snort-inline box in place, I can attain about 2.5Mb/sec
> downloads on my line.  With it in place, I'm stuck at about 300kb/sec
> I currently log to MySQL (ACID) but disabling MySQL, offloading it to
> other machines and kicking up the memcap for stream4 (from 8 megs to
> 256) have made no difference so far.
> The server load is about 0.01 and I'm not seeing it struggle at all --
> has anyone else done performance tuning on snort to this degree? Are
> there some iptables directives I can use to improve performance?
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