[Bro-Dev] #861: Merging DNP3 Analyzer
Bro Tracker
bro at tracker.bro-ids.org
Fri Oct 26 11:16:16 PDT 2012
#861: Merging DNP3 Analyzer
---------------------+------------------------
Reporter: hui | Owner: robin
Type: Task | Status: assigned
Priority: Normal | Milestone: Bro2.2
Component: Bro | Version: git/master
Resolution: | Keywords: dnp3
---------------------+------------------------
Comment (by hui):
HI, Robin,
Can you please take a look at current version of the codes. I added
documentation on the analyzer.
The work that left undone so far is
(1) so far, we support logic DNP3 application layer fragment as long as
65536.
(2) documentation on protocol validation policy, the policy that checks
some rules defined by DNP3 protocols
Best,
Hui Lin
On Sat, Oct 6, 2012 at 8:30 PM, Bro Tracker <bro at tracker.bro-ids.org>
wrote:
> #861: Merging DNP3 Analyzer
> ---------------------+------------------------
> Reporter: hui | Owner: robin
> Type: Task | Status: assigned
> Priority: Normal | Milestone: Bro2.2
> Component: Bro | Version: git/master
> Resolution: | Keywords: dnp3
> ---------------------+------------------------
>
> Comment (by hui):
>
> Replying to [comment:12 seth]:
> > > I think what you said is the "incremental parsing"
> > > mentioned in the binpac paper. But actually, I am not quite sure
how
> this
> > > is implemented in the binpac. Can you please direct me to some
codes
> that
> > > I refer to?
> >
> > It's actually not something you even need to worry about. Just
> instantiate your binpac parser and begin passing data into it as you
> receive it, the binpac parser will take care of the data even if it
> doesn't receive the full PDU in one go.
>
> Just come up another question. When a HTTP fragment is very long and
> carried in different network packets, the HTTP binpac analyzer should
know
> the length of the whole fragment when the first application layer trunk
is
> received. Is this correct? The HTTP message contains some field to
> indicate that length, right?
>
> But for DNP3 analyzer, this is not possible. I know the length of the
> whole logical DNP3 fragment only when the last trunk is received. To
> better explained
>
> TCP : DNP3 Pseudo Data Link Layer (length field is 255) : DNP3 Pseudo
Data
> Transport Layer : DNP3 Pseudo Application Layer #1
> TCP : DNP3 Pseudo Data Link Layer (length field is 255) : DNP3 Pseudo
Data
> Transport Layer : DNP3 Pseudo Application Layer #2
> ....
> TCP : DNP3 Pseudo Data Link Layer (length field is x) : DNP3 Pseudo
Data
> Transport Layer : DNP3 Pseudo Application Layer #n
>
> So the length field in the Pseudo Data Link does not contain the length
of
> the whole DNP3 fragment, but the length of the trunk following this
data
> link layer. So in order to know the whole length of the DNP3 fragment
(in
> this case is , 255 + 255 + ... + x), all the application layer trunk
has
> to be received. So is there any way to use incremental parsing in the
> binpac in this case?
>
> --
> Ticket URL: <http://tracker.bro-ids.org/bro/ticket/861#comment:13>
> Bro Tracker <http://tracker.bro-ids.org/bro>
> Bro Issue Tracker
>
--
Ticket URL: <http://tracker.bro-ids.org/bro/ticket/861#comment:14>
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