I'm going through the iptables tutorial and am currently at Chapter 6, Traversing of tables and chains.
I'm having trouble understanding the why's behind Tables 6-1, 6-2, and 6-3 listed in the above chapter.
Is there a better book or online resource where a better explanation can be found?
Am I supposed to rote-learn / memorize the various steps covered in these tables?
The above tutorial appears to be many years old. Is everything said of
iptablesin there still 100% valid. The
iptablesversion that I have on my system is
All these questions are arising mainly because I so far 'feel' that, maybe, all that
iptables should have done was provided us with a bare minimum set of hook-points (like, e.g. pre- and post-routing hooks), and an ability to do arbitrary packet processing (in any sequence that we deemed fit and any number of times - a custom state machine) instead of stipulating the detailed sequence of steps as in the above Tables. For example, in the diagram that follows Table 6-3, why should the 'filter input' step come only after 'mangle input', and not before? And, why not both before and after? Etc.