Snort mailing list archives

Re: Discrepency between Base and linked packet


From: Joel Esler <eslerj () gmail com>
Date: Tue, 24 Mar 2009 08:50:32 -0400

We'll need to know more about the setup.  BASE simply reads what is in the
DB.  If it's a parsing issue with BASE, reading out of the DB, then Kevin
can speak to that, however, if the problem lies in the data that is actually
in the DB, then I have to ask how it is getting in there.
Generally Accepted Best Practice is to have Snort log in "unified" mode, and
have an external tool like barnyard or SnortUnified.pm read the Unified
files and put them into the DB.

How is your setup configured?  (Writing from Snort directly to the DB is
never recommended.)

Joel

On Tue, Mar 24, 2009 at 8:44 AM, Bruno G. San Alejo <bgonzalez () polar es>wrote:

   Hi everyone, I posted like 4 weeks ago something about some problems
with what Snort logs, what Base shows, and what Base saves as pcap file.
Maybe that is what you are talking about?

   What I saw was that the packet logged with Snort was the right one.
The packet logged to the DB had some issues. These could be seen in:

   -what Base shows, for ICMP redirect packets (that was what I was
focusing on) the id and the seq# were being logged instead of the
gateway's IP, I submitted a temporary fix that takes care of it and I'm
currently testing a fix for Snort and Base that will definitely take
care of this if they are approved. The problem was the way that the
packet was being parsed and the schema at the DB, which had fields that
are not present in all the types of ICMP, but that are non null.

   -what Base saves in pcap, wrong MAC addresses and shorter
timestamps. As you say, discrepancies at the Network, Transport, and
Data layers. I have not look into this as I am working in the other
issue, but if no one comments on this one, I'll dive into the code shortly.

   Thanks.

Matthew Babcock wrote:
Hello all,

A short time back I noticed someone was talking about an issue where the
packet downloaded via base had different headers then shown between
wireshark and base.

The top layers are represented the same in Base and the .pcap. However
the
bottom layers are not correct. The data in the Data Link and Network
layers is just wrong, the Transport layer also cites bad TCP Checksums.
Thanks in advance.

What was the reason and fix?

Also, is the mailing list archived somewhere?


Regards,
-- Matthew R. Babcock
CEO, Principal Consultant
A & R Technology Consulting - Providing solutions, not limitations -
MBabcock () AandRTech com
(508) 397-8280





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easily build your RIAs with Flex Builder, the Eclipse(TM)based development
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-- 
Joel Esler
T: 302-223-5974 (-) Gtalk: jesler () sourcefire com
[m]
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