[Snort-users] Alerting unified or (fast) ASCII?

Edin Dizdarevic edin.dizdarevic at ...7509...
Wed Oct 20 09:18:17 EDT 2004


Matt Kettler wrote:

> At 09:50 AM 10/20/2004, Edin Dizdarevic wrote:

> Unified will allow snort to handle a significantly larger load, as
> most of the data is written out in the raw binary format it appears
> in the IP packet. ASCII mode logging reuqires some additional
> translation.

Allright, I assumed that isn't really that much work to do.
Obviously the effort is far not negliable. :(

>> After all a second by instance for alerting (besides logging) is
>> needed.
> Ahhh, but here's where you're missing something. The fact that
> barnyard is used does not speed up long it takes to get alerts
> written into a textual format. However, it removes the ascii
> conversion from snort's time-critical packet capture process. This
> greatly reduces packet drop rate.

Yes, but it consumes system ressources, memory and cpu cycles.
Especially if more than one alert has been triggered by will try to
process the previous entry during the same time another alert may occur.
I'm not that good in programming but by's file access should be
non-blocking otherwise it may hinder Snort. I suppose that is anyway the

> The overall CPU consumption is the same, but the time-critical path
> is much shorter in the unified/barnyard case.

Good to know. I already thought the effort writing start scripts for two
by instances has been useles ;). On the other side I experienced no
packet at all drops the on the 100Mbit line since (in spite of Arkeia).


Edin Dizdarevic

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