Snort mailing list archives

Re: help with rules - data capturing


From: Joel Esler <joel.esler () sourcefire com>
Date: Fri, 21 Dec 2007 21:29:12 -0500

Rule of thumb.  Regardless of the problem you are having, always  
update to current version (2.8.0.1) before asking for help.  That is  
usually the first troubleshooting step.



--
Joel Esler
joel.esler () sourcefire com




On Dec 21, 2007, at 8:01 PM, Timothy Ding wrote:

many thanks for the reply Paul, i still don't get any results from  
the rule, could it possibly be the version of snort (ver 2.3.3) that  
i am using?

Regards,
Tim

I think it should work pretty much as-is, but here is how I would
write the rule:

alert tcp any any -> $HOME_NET 13001 (msg: "GPRMC found in packet"; \
flow:to_server,established; content:"|24|GPRMC"; nocase; sid:9999000;)

Use the flow: directive to only analyze packets that are in-state for
the connection described.  I also hexified the $ in $GPRMC just to be
safe.  That way it doesn't get treated like a variable by anything
that parses that rule.  And then use some non-published sid value so
that if you're using BASE, SGUIL, or something else that lets you
search/sort by sid values, you can access it.

PaulM

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