[Snort-users] Discrepency between Base and linked packet

Bruno G. San Alejo bgonzalez at ...14528...
Tue Mar 24 09:25:01 EDT 2009


    OK, my fault then, I just run Snort and Base. Snort is configured
with MySql support and Base just goes into the DB. Sorry, I just
installed them a couple of months ago and followed the "Managing
Security with Snort and IDS tools" book and the typical "how-to" web
pages. I guess I need to do more homework. :)

    Then, given that Snort logs right the packets and that a external
tool gets the log file and puts it into the DB (I had and have no idea
about this, I won't BS you), the DB schema is not quite right anyway. It
has two fields (id and seq#) for ALL ICMP types. Particularly for ICMP
redirects, the gateway's IP is not represented anywhere in the DB schema.

    So, if I'm not wrong the root issue of this thread gets solved: use
an external tool to pass the Snort logs into the DB (as a matter of fact
the first thing I'll start doing as soon as I send this email). But for
everything to be peachy there is still the little issue of some
discrepancies between some ICMP types and what data is in the DB schema
representing them. I just don't see how even with an external tool, 
some data of  ICMP packets can be logged into the DB if the schema just
doesn't have those fields.

    Thanks.

   



Joel Esler wrote:
> 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 at ...14528... <mailto:bgonzalez at ...14528...>> 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 at ...14532...
>     > (508) 397-8280
>     >
>     >
>     >
>     >
>     >
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> Joel Esler
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> <mailto:jesler at ...1935...>
> [m]





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