Re: Snort with an expert system

[Stefano Zanero <s.zanero () securenetwork it>]

> "A false positive is an alert that triggers on normal traffic where no
> intrusion or attack is underway"

That's a good definition, but not really complete. Under that
definition, if you place a rule that flags IRC connections, and it
fires, is that a false positive?

Is it a false positive a case where there is no rule, or the traffic
does not match with the rule, and the engine still fires?

Is it a false positive a case where a rule correctly matches, but the
user didn't want to be alerted to that traffic ?

> In addition, I don't understand why there would be no reason that this
> algorithm would work. Could you explain? The algorithm is developed by
> experts in Bayesian statistics and has been applied in other fields as
> well.

The algorithm type has apparently no relevance to the problem. Why
should a false positive be statistically different, in the sense you are
considering, from a true positive?

Best,
Stefano

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