[Snort-users] flow:established still broken in 2.9.0.5?

Jason Haar Jason.Haar at ...294...
Wed Jun 29 18:12:33 EDT 2011


On 30/06/11 09:33, Russ Combs wrote:
>
> depth:2 applies to the current packet (raw or reassembled).  It is not
> a depth from beginning of stream.

Ahhh! the penny drops - so it should be expected to get FPs due to this
then? Shouldn't there be a "streamdepth:" option then? Almost all TCP
protocols are defined by their first few bytes, so checking only the
beginning of a stream should improve things for many rules? I have
routinely seen FPs caused by this with SSL and ZIP/compressed data flows
- almost all would be removed if there was a "streamdepth" sort of option.

(I've just checked the manual and indeed "depth" is only about packets,
not streams - and yet all the "tcp_stream" options in snort had lead me
to believe it did something more precise - my mistake :-)

-- 
Cheers

Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1





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