Re: Rule efficiency

["Isherwood, Jeffrey - IS" <Jeffrey.Isherwood () itt com>]

If it turns out that mgmt DOES want just web traffic, the use of the http_header will tell the sensors to stop alerting 
on the content on pages then correct?  I have been getting false positives where a user visits a page with a link or 
mention of "crappydomain.com" on it and that visit sets off the alert...


Jeffrey Isherwood, CISSP, C|EH
Computer Security Analyst | Enterprise Protection & Planning
Information Systems | Information Protection & Sharing

From: Alex Kirk [mailto:akirk () sourcefire com]
Sent: Friday, July 23, 2010 3:01 PM
To: Isherwood, Jeffrey - IS
Cc: snort-users () lists sourceforge net
Subject: Re: [Snort-users] Rule efficiency

For what it's worth, the use of the fast_pattern keyword when there's a single content clause is actually unnecessary. 
The fast pattern matcher by default chooses the longest string available out of a rule, and if you've only got one 
string, well, it'll choose that every time.

Good luck with your management quandary.
> On Fri, Jul 23, 2010 at 2:33 PM, Isherwood, Jeffrey - IS <Jeffrey.Isherwood () itt com<mailto:Jeffrey.Isherwood () itt 
> com>> wrote:
>
> Thanks for the reply Alex...  For reasons that I can't go into, I am not able to check the DNS queries (alas, that was 
> my original thought as well).


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