linux. iptables. How does it work?

Question

linux

Hello. I am writing my thesis. I need to write about the operation of the iptables utility in as much detail as possible. I have already read a fairly large number of articles, but I have not found anywhere exactly how this utility works. Everywhere they write how it works (that it checks the condition and rejects / accepts the packet, chains and tables are described), but nowhere is it written exactly how this happens. What files are involved. What exactly processes each packet.
Please advise how I can study the work of Iptables in as much detail as possible. What to read or how to look at the code\track everything that happens with the package. Ubuntu 14 OS
. Many thanks in advance.

Answer 1

https://ru.wikibooks.org/wiki/Iptables
https://www.opennet.ru/docs/RUS/iptables/help.ubuntu.ru/wiki/iptables
https://wiki.archlinux.org/index
. php/IPtables_(%D0...

Answer 2

Diploma in iptables Original ...
Well, open the netfilter sources and go ....