Snort mailing list archives
Re: High Speed Network Cards + rules?
From: Matt Kettler <mkettler () evi-inc com>
Date: Mon, 24 May 2004 16:21:26 -0400
At 02:18 PM 5/24/2004, Adriel T. Desautels wrote:
It is my understanding that most network cards at 50% capacity begin to miss packets and create a false negatives condition (IDS evasion technique). Is anyone aware of any cards that exist that collect 100% of the traffic with 0% false negatives due to this condition? If not, what is the next best thing?
So what kind of "high speed" are we talking here? gigabit? 100mbit?And technically speaking, it's usually not the NIC that misses the packets. However, the CPU overhead from the NIC can cause snort to not have enough CPU time to get to them.
Some general suggestions to improve performance on sniffers using gig-e interfaces:
1) Use a on-motherboard CSA based setup, or 64bit PCI bus, or PCI-X. A classic 32bit/33mhz PCI bus can just barely transfer 1Gbit/sec with nothing else going on and no overhead. 2) Look at the driver source code for the NICs you're considering for your OS. The source often contains hints if a particular card is inefficient or not. 3) Be sure to use a high performance PCAP library like the MMAPed IO one from Phil Wood. 4) Make sure your memory subsystem is fast. Make sure you're using the fastest RAM that your chipset can handle. 5) Make sure you're not doing anything silly like ascii-mode packet logging. Log in SQL, or tcpdump format.
Tom's hardware also did a test of several "on-motherboard" gig-e implementations from which we can glean some useful information:
http://www.tomshardware.com/motherboard/20040430/index.htmlBe sure to look at both thruput and CPU numbers.. The intel chipsets using CSA clearly won overall. Consistently first or second place thruput, and the low CPU usage. The Realtek chip also did well in one performance test, but it's CPU loading was also high (70%).
You need to keep in mind that these tests were done on windows, but it does give you some basis of comparison.
Also keep in mind that most chips other than the CSA setup are going to be using an on-motherboard PCI setup, and are probably connected at 32bit/33mhz. (Tom confirms this for the Broadcom, and I can confirm the realtek chip on the board is 32bit only). If nothing else, the performance difference of the CSA chip suggests that 32bit/33mhz pci just can't keep up.
Even comparing apples-to-apples using only PCI implementations, the Intel PCI plug-in card looks better than the broadcom, 3com or realtek here.
Secondly, does anyone know of any other snort rule repositories aside fromthose presented at snort.org?
I for one do not, other than the snort-sigs mailing list, but perhaps someone else does.
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Current thread:
- RE: Snort and high performance networks, (continued)
- RE: Snort and high performance networks snort user (May 21)
- Re: Snort and high performance networks Christopher Rapier (May 21)
- RE: Snort and high performance networks Rafael Ortega (May 21)
- Re: Snort and high performance networks snort user (May 21)
- RE: Snort and high performance networks SN ORT (May 21)
- RE: Snort and high performance networks Kreimendahl, Chad J (May 21)
- Re: Snort and high performance networks Aaron (May 24)
- High Speed Network Cards + rules? Adriel T. Desautels (May 24)
- Re: High Speed Network Cards + rules? Keith W. McCammon (May 24)
- Re: High Speed Network Cards + rules? Christopher Rapier (May 24)
- Re: High Speed Network Cards + rules? Matt Kettler (May 24)
- Re: High Speed Network Cards + rules? James Riden (May 24)
- Re: High Speed Network Cards + rules? James Riden (May 25)
- High Speed Network Cards + rules? Adriel T. Desautels (May 24)
- RE: Snort and high performance networks snort user (May 21)
- Re: High Speed Network Cards + rules? Tod Beardsley (May 24)
- Re: Re: Snort and high performance networks Aaron (May 25)
- Re: Re: Snort and high performance networks Micha Silver (May 26)
- Re: Snort and high performance networks Chris Rapier (May 20)