journey through IPTables looking for documentation

[S/C Conway <seconway@mts.net>]

G'Day,
What is the path data takes to complete its journey through IPTables?

Many of the documents I have read provide in detail the rule
construction of a firewall.  I have a working firewall. Rule
construction is not my goal. I am trying to understand IPTables in
microcosm. My question is to help develop a better understanding of data
movement within IPTables. 

I have constructed through research a diagram that shows the chain path
through IPTables superimposed over a physical network. I am at a
crossroad because my research conflicts with what I see through protocol
analysis. I am missing some key piece of knowledge.

I am looking for someone who has knowledge of IPTables and is willing to
wear a tank to go "deep". I would like to start by reviewing the drawing
and providing some suggestions. I am willing to share my research.

Sean D. Conway