RE: rules with flow:established not working

["Ed Callahan" <snort () edcallahan com>]

Paul -

The problem isn't that Nitko isn't a good test of the rules. The rules don't
trigger a response when they include flow:established, and do trigger a
response without the flow:established, when I use my browser to test the
rules (i.e. when I'm not using Nitko). So the flow is established, but for
some reason snort doesn't know that.

When I remove the "established" from the rules in web-iis.rules snort
detects all sorts of attacks from IP addresses all over the world. Putting
the "established" back results in silence.

Ed Callahan
snort () edcallahan com

On Fri, 24 Oct 2003 Paul Schmehl wrote:

> On Fri, 24 Oct 2003 Ed Callahan wrote:
>
> How does snort know the flow is established?

Erek can correct me if I'm wrong, but I'm pretty sure it's the three way
handshake, and I'm *not* sure that Nikto does that.  I think it may just
throw exploit strings at the server and look at the responses.  If so,
that would explain why the flow:established rules aren't triggering
alerts.

> Can I look at
> the packets to see if the problem is with the NIC/OS or with
> WinPCap/Snort?
I would think that ethereal would show you what's going on.  Just start
it up and record the session and then browse through the results.

Paul Schmehl (pauls () utdallas edu)
Adjunct Information Security Officer
The University of Texas at Dallas
AVIEN Founding Member
http://www.utdallas.edu/~pauls/




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