Pass through packets
Guillaume
silencer at free-4ever.net
Wed Mar 28 08:37:22 UTC 2007
>> With iptables
>> we can set a rule: iptables -t filter -A FORWARD -i eth0 -o
>> eth1 etc....
>>
>> With packet filter how can I have a such way of processing my packet ?
>>
>> If a setup a rule pass in on $if_internal inet proto tcp \
>> from $internal_networks to any \
>> flags S/SA modulate state
>>
>> The packet from my internal networks can also exit on my DMZ
>> interfaces !
>
> Not if you run a default block policy it wont.
>
I've seen my problem
I have a rule with is something like opendoor for outgoing packet from
the firewall...
And NAT rules are applied before filtering rules.
SO for traffic going from internal to external, I only have to setup a
pass rule on the internal interface !
But for packet going from internal to dmz
I have to setup 2 rules.... one with pass in on the internal interface
and another one with pass out on the dmz interface !
> The 1st packet filtering rule of every pf policy should be
>
> block log all
>
> From there only permitted ingress & egress flows will be permitted.
>
Yep... that's what I have done now.
So if I want a very accurate filtering for forwarding packets, I must
setup 2 rules every time... one pass in on the incoming interface and
another with pass out on the outgoing interface...
>> Is the only way to setup that is to specify a destination
>> with ! { $dmz_networks1, $dmz_networks2 } ?
>
>
> There's a number of ways to skin this particular cat.
>
> I am partial to using generic egress rules in combination with tagging
> myself.
>
I'll check the egress rules...
> My personal PF policy style is to code '1st' match by using 'quick' on every
> rule.
Mee too
> Whether that's a consequence of being infected with the Checkpoint and Pix
> virus at an early age, I know not :-).
>
LOL
i'm infected with Linux netfilter/iptables... :-)
> I would also counsel against the use of 'any'.
> Negation is a mite more logical and less error prone on larger policies
> IMHO.
Ok... I'll think about that too
> Tables will also reduce macro expansion.
>
Ok... the same :-)
Thanks
>
> Greg
>
Guillaume
--
Guillaume
E-mail: silencer_<at>_free-4ever_<dot>_net
Blog: http://guillaume.free-4ever.net
----
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