per-interface packet filters, design approach

[Josh Kayse]

As someone who is quite new to all of this, take my thoughts with a
grain of salt.  That being said, this is my view on the matter.

On Tue, 14 Dec 2004 15:03:27 +0100, Andre Oppermann <andre at freebsd.org> wrote:
> Let's take a high level view of the issue at hand and the consider
> some alternative approaches to the situation.
> 
> Current situation:
<snip> 
> Implementation approaches:
> 
>  d1. The PFIL_HOOKS API has one hook per direction per protocol and
>      passes the interface information to the firewall package.
>  d2. Should the PFIL_HOOKS API be changed and be per interface instead
>      of per protocol?  All firewall packages need to be modified and
>      we are no longer compatible with the PFIL_HOOKS API.

I don't think so because as has been said, the PFIL_HOOKS API provides
all the needed information.

>  d3. Should the interface specific rules sets be per firewall package
>      in the way that best suits the package?  No kernel API is changed.
>  d4. What is the user interface syntax and semantics for each firewall
>      package that someone wants to be modified?  Provide examples for
>      those you are interested in.
>  d5. Should it be a replica of Cisco|Juniper approaches or can we do
>      better in syntax or semantics?  Think outside of the box.
> 
> Lets continue the discussion from here.
> 
> --
> Andre
> _______________________________________________
<snip>


I think so as it would be the best change, in my oblivious opinion.  I
would see it as the firewall package receives the mbuf, checks the
interface, if it is processing rules on the interface, or if there is
a global set of rules, to then continue processing the packet.  If it
isn't, it should just return/get out, whatever.  I do believe this
would require a change in rule processing.  The firewall package would
keep track of the different 'chains' for the rulesets.

As far as writing rules go, I think that it would be simple to make a
script that takes a set of firewall configuration rulesets and merges
them so that they do not collide.  I think it take more work to get it
to make it pretty, but I don't see it being impossible.

I'm sure that I'm not understanding exactly what the problem is, so
please, let me know what I'm missing, thanks.

-- 
Joshua Kayse
Computer Engineering