ipfw/nated stateful rules example

[Alex Zbyslaw]

fbsd_user wrote:

> The conclusion so far is that ipfw1 and ipfw2 using keep-state rules
> on the interface facing the public internet with divert/nated does
> not work period. 

Probably my post hasn't reached you yet.  I think you are mistaken if you mean 
that keep-state rules cannot be securely used in a NAT configuration -- see 
two examples in my post.  The mistake I believe you are making is in talking 
about only the public-internet facing interface.  What you are trying to do is 
to ensure that *conversations* from anywhere on your internal network can be 
keep-stated when talking to the external network.  But the packets *start* on 
the internal facing interface.  It just so happens that without NAT you can 
ignore this bit of the conversation, but once you include it, you cannot.

In any case, my somewhat messy example which puts the keep-state on a skipto 
rule still manages without *looking* at the internal interface, though it does 
take into consideration the whole conversation.

> Still would like to be proved wrong on my conclusion.

If you find any bugs in the two alternatives I posted then I would love to know.

--Alex