Snort mailing list archives

Re: byte_jump + Stream5, should it work?


From: rmkml <rmkml () yahoo fr>
Date: Sat, 24 Dec 2011 16:39:14 +0100 (CET)

Hi Shaiming,
Can you share a pcap example please?
Can you test with last snort v2.9.2 please?
Can you try with default snort.conf with minimal change?
Can you post your snort.conf + pcap + snort cmd line + snort verbose output ?
Can you post a rule + pcap describe exactly your pb please?
Happy Detect with Snort / Suricata / Bro.
Merry Christmas everyone.
Rmkml


On Fri, 23 Dec 2011, Shaiming Hsiung wrote:

Hello,

I am attempting to use Snort (version: 2.9.1.2 IPv6 GRE (Build 84))
to filter application-level packages in binary length-encoded
format.

The Stream5 and HttpInspect preprocessors are enabled.

As far as I understand, when Stream5 is enabled, Snort is
able to detect packages matching "content:" rules, even if
the target string is fragmented across multiple TCP packages.
Experience seems to confirm that.

However, when I use "byte_jump:" rules, Snort seems not
to be able to jump past the TCP package boundary, even
though Stream5 is enabled.

I haven't found any documentation in the Snort User's Manual
regarding the relationship between the "byte_*" rules and
Stream5.

Is that the expected way it should work?

Is there any way of making "byte_jump:" behave as if the
contents were a stream?

Thank you in advance for your help.

Regards,

--
Shaiming Hsiung



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