Hi,
I was looking into the iptables implementation and was intrigued about
how iptables would handle a situation in which we have identical rules
except for their targets which are contradicting, say ACCEPT and DROP.
By looking at ipt_do_table() function it seems that the first
non-IPT_RETURN verdict from any standard target will end the traversal
of a chain of a table, which seems to be a bit odd. First, such
conflicting rules must not be allowed. Even beyond, this fails in the
situation where you have a dropping rule added after an accepting rule.
For example, a packet from m.n.o.p to a.b.c.d would be accepted at
a.b.c.d because of the first rule, although it had to be dropped
according to the second rule. And this would result because of the
order in which the rules are added to the table.
iptables -A INPUT -d a.b.c.d -j ACCEPT
iptables -A INPUT -s m.n.o.p -j DROP
Is my understanding correct? If so, I am curious to know how nf-hipac
behaves in such situations?
waiting for reply,
--
Venkatesh Prasad Ranganath,
Dept. Computing and Information Science,
Kansas State University, US.
web: http://www.cis.ksu.edu/~rvprasad
