IP over PPPoe:PPP extraction

Hi there,

I found a post of this mailinglist here:
http://article.gmane.org/gmane.linux.network.bridge.ebtables.devel/413/match=ppp

It appears that this patch has never made it into the code. I am very
interested in this functionality and would be willing to code if
provided with some ideas/hints. (I am know kernel insider -- yet ;-) but
I think using the tutorial online it can't be so difficult).

First, here is what I need: A way to extract and redirect certain IP
packets (depending on the IP header) from an Ethernet:PPPoe:PPP: stream.

>From Barts answer I deduct that a general solution would be better than
to add this PPPoE/PPP extraction to every embeddeble protocol and every
embedding protocol. I had a look through the tutorial and the sourcecode
but from what I gathered the functionalities of different filters are
not easily combinable ? If I understand the approach that Thomas
ESTASECCA wanted to patch-in: apply the PPPoe:PPP extraction first and
then test for the usual IP header/fields against the rule spec. 

The general approach that I thought of would be: Define a Matcher that
identifies PPPoE:PPP combinations, then define a Target or a Table where
the payload(y) of the x:PPPoE:PPP:y packet can be examined further using
existing filters like IP with its existing code. I am sorry if I mix
terms up (like Table and Target) but I am still at the beginning to
understand the code and the inner workings. To my knowledge there are
Targets that manipulate the packets like DNAT,SNAT,... but what would be
needed here is an approach to filter PPPoe:PPP out and then run the
other matchers against the payload.

I would appreciate any help or infos regarding an elegant and general
solution. Please forgive my shallow knowledge of this matter.


Marek Jawurek