IDS: Re: Question on resources needed to manage IDSes

[Jeff Nathan <jeff () snort org>]

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On Dec 2, 2003, at 9:44 AM, simonis () att net wrote:

> > I am looking for a rule of thumb, something like this:
> > 1-5 IDS sensors - 1 Analyst
> > 5-15 IDS sensors -2 Analysts
> > 15-50 IDS sensors- 3 Analysts
> > 1 Analyst for every 30 additional IDS sensors.
> Are these the number of folks "at the screen" or the head count 
> required?
> If the latter, remember folks get sick and take vacation.  Also, 
> consider
> the need for 24x7 monitoring.  Such considerations really scale up the 
> number
> of bodies required.
[...]

> Your numbers, however, don't make much sense.  What about that 3rd 
> analyst is
> so special that they enable the monitoring of an additional 35 
> sensors, when
> a single analyst alone can only monitor 5?  Then, after 50 sensors, an 
> add
> anaylst only enables the monitoring of an 30 more sensors.  I suspect 
> a more
> linear scale is likely.
A more reasonable approach would probably be to consider the alert 
rates in question and how many of them need to be looked at by a human 
being.  It would be generous to assume a human could qualify a 
reasonably complex alert in 30 seconds.  After that, it's simply a 
matter of doing the math.
One analyst for 30 sensors might scale if those sensors had very low 
alert rates.  I don't think this is a sufficient model for staffing 
analysts.
I'd determine what the alert rates are and of those alerts how many can 
be qualified in post processing automatically.
- -Jeff

- --
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