[Snort-users] flow:established still broken in

Jason Wallace jason.r.wallace at ...11827...
Wed Jun 29 21:39:06 EDT 2011

If you are frequently getting FP on ssl/tls/ssh traffic, even though
you have this data set to ignore in the ssl/ssh preprossors, then make
sure all your ports that are supporting this type of traffic are in
both the ssl/ssh preprocessors and in stream5. They have to be listed
in "ports both" section for the ignore options to work correctly. I
don't know for sure but tls smtp traffic might follow this rule too.

I see in the snort.conf for 2.9.1_beta port 22 is only list in "ports
client". Shouldn't this be in "ports both" to function correctly?


On Wed, Jun 29, 2011 at 6:12 PM, Jason Haar <Jason.Haar at ...294...> wrote:
> 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
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