Re: Second Snort instance killing performance

["Alex Butcher, ISC/ISYS" <Alex.Butcher () bristol ac uk>]

--On 07 September 2005 10:49 -0400 Paul Melson <pmelson () gmail com> wrote:

> I've just run into an interesting situation with one of my Snort sensors.
> I've added another interface attached to a new span port to my existing
> sensor box and I want to run a second Snort process for that interface.
> Same binary, same logs, but different config file and rule set for each
> process.  If either the original process monitoring eth1 or the new
> process monitoring eth2 are running, the load average is about 0.3-0.4.
> If both processes run simultaneously, load jumps to 2.0+ and performance
> suffers, packets drop, etc.
>
> The server is a Proliant G4 running RHEL4 with dual Xeon 3GHz CPUs, 2GB
> RAM, Ultra320 disks, etc. so it shouldn't be choking on this relatively
> small amount of traffic.  Snort version is Version 2.3.2 (Build 12).

What libpcap are you using? Distribution standard, or Phil Wood's?

> Anybody run into anything like this before?  The problem seems to be
> specific to running two Snort processes, but I'm not sure where to
> troubleshoot next.

One suggestion I have is to re-arrange your rules so that you bond eth1 and 
eth2 together to create bond0, then run a single Snort on bond0. Obviously, 
there are disadvantages to doing that, but advantages also (state tracking 
across interfaces, for instance).

> PaulM

Best Regards,
Alex.
--
Alex Butcher: Security & Integrity, Personal Computer Systems Group
Information Systems and Computing             GPG Key ID: F9B27DC9
GPG Fingerprint: D62A DD83 A0B8 D174 49C4 2849 832D 6C72 F9B2 7DC9




-------------------------------------------------------
SF.Net email is Sponsored by the Better Software Conference & EXPO
September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices
Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA
Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf
_______________________________________________
Snort-users mailing list
Snort-users () lists sourceforge net
Go to this URL to change user options or unsubscribe:
https://lists.sourceforge.net/lists/listinfo/snort-users
Snort-users list archive:
http://www.geocrawler.com/redir-sf.php3?list=snort-users