Snort mailing list archives
RE: Snort as Gigabit Sensor
From: Banniza Robert <Robert.Banniza () HCAhealthcare com>
Date: Thu, 24 Jul 2003 14:27:15 -0500
Here's a little more information I forgot to provide in the first post. The machine is an IBM x335 Xeon with dual 2.6Ghz procs and 1GB RAM. As for the logging portion, I am not using Barnyard (yet)....We were setup to log to Postgres and to syslog. However, we did notice something interesting...With all logging turned off and just sniffing with the default ruleset, we were still dropping packets. Also, by placing 8 pass rules in local.rules, this accounted for about 6-7% of the packet loss. Therefore, if we turned the pass rules off (commented out local.rules), our packet loss would drop down to 33% or so. Robert -----Original Message----- From: Demetri Mouratis [mailto:dmourati () cm math uiuc edu] Sent: Thursday, July 24, 2003 2:19 PM To: Banniza Robert Cc: 'snort-users () lists sourceforge net' Subject: Re: [Snort-users] Snort as Gigabit Sensor On Thu, 24 Jul 2003, Banniza Robert wrote:
Anyone have any good pointers on tuning Linux (Redhat 9) as a gigabit sensor? Currently, we are using a Broadcom Corporation NetXtreme BCM5703 Gigabit Ethernet (TG3 kernel module) Netgear card as the sniffing card. We have set up a span port so that we can see all traffic on a Cisco 6509.
The
sad thing is we are encountering 40% packet loss. The network interfaces were statically compiled into the kernel and /etc/sysctl.conf was modified with the following to provide larger buffers:
<snip>
We have not performed any rule tuning yet and the current sustained throughput we have seen through this connection is around 14Mb which is nowhere close to gigabit speeds. Any ideas?
Turn off all the pre-processors first, especially spp_conversation and spp_portscan. They tend to eat up memory. Next thing I would look at is throwing out uneeded traffic analysis for protocols/nets you aren't concerned with. The 6509 is probably a core switch right? Consider what you are willing to live without checking at that layer of your network. You can do this with BPF filters or pass rules. Make sure you are logging in a sane fashion. Best thing would probably be barnyard to decouple the sensing from the analysis. You didn't mention anything about the sensor itself (Processor(s), RAM, Disks). Those will undoubtedly affect your performance as well. If you go through all these steps and still can't capture enough traffic, you may have to re-architect the thing to use two sensors, each on half of your network. Again, use BPF to set this up. You are going to have to pare down the default rule list no matter what. Hope that helps. --------------------------------------------------------------------- Demetri Mouratis dmourati () linfactory com ------------------------------------------------------- This SF.Net email sponsored by: Free pre-built ASP.NET sites including Data Reports, E-commerce, Portals, and Forums are available now. Download today and enter to win an XBOX or Visual Studio .NET. http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01/01 _______________________________________________ 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
Current thread:
- Snort as Gigabit Sensor Banniza Robert (Jul 24)
- Re: Snort as Gigabit Sensor Erek Adams (Jul 24)
- Re: Snort as Gigabit Sensor Demetri Mouratis (Jul 24)
- Re: Snort as Gigabit Sensor twig les (Jul 24)
- Re: Snort as Gigabit Sensor Bennett Todd (Jul 24)
- Re: Snort as Gigabit Sensor Jeff (Jul 24)
- Re: Snort as Gigabit Sensor Jason Haar (Jul 24)
- Re: Snort as Gigabit Sensor Jeff (Jul 26)
- DCOM exploit snort signature jason (Jul 27)
- Re: Snort as Gigabit Sensor Jason Haar (Jul 24)
- Snort in Linux kernel mode Paul B. Poh (Aug 05)
- <Possible follow-ups>
- RE: Snort as Gigabit Sensor Banniza Robert (Jul 24)
- RE: Snort as Gigabit Sensor twig les (Jul 24)
- Re: Snort as Gigabit Sensor Irwan Hadi (Jul 27)
- Re: Snort as Gigabit Sensor Marc Quibell (Jul 24)
- RE: Snort as Gigabit Sensor Banniza Robert (Jul 24)
- RE: Snort as Gigabit Sensor Hutchinson, Andrew (Jul 25)
- RE: Snort as Gigabit Sensor Kreimendahl, Chad J (Jul 25)
- RE: Snort as Gigabit Sensor Kreimendahl, Chad J (Jul 29)
- Re: Snort as Gigabit Sensor Chris Green (Jul 31)
- Re: Snort as Gigabit Sensor Frank Knobbe (Jul 31)
- Re: Snort as Gigabit Sensor Chris Green (Jul 31)
- Re: Snort as Gigabit Sensor Chris Green (Jul 31)