jEopardy : the revolution

Being a human, I forget everything... It has been 5 days since my last study on netfilter and I forget insert_rules function`s details. So today it will be a restart day. Because I am working on a patch for iptables.c which will prohibit a user to insert same rule one after another, I need to understand how a rule is inserted to memory, how two rules can be matched and how a rule with a rulenum can be found.

I am working on insert_rules which is used both by TC_INSERT_ENTRY and TC_APPEND_ENTRY. As you may already know append adds the rule as the last rule of the chain, insert adds the rule to the position which is mention in rulenum.