Re: Iptables is driving me nuts (beginner)
Quoting n/a <test@pandora.be>:
> Hello there,
>
> For the past couple of days i've been looking into setting up an old pc as a
> firewall/router for a couple of students.
>
> To do so i enabled iptables and started looking into configuration issues.
> Eventually i came up with a config that worked. haha. Then i realised this
> config was fishy and started deleting lines as i went along. Now almost no
> lines are left and the darned thing still works even after reboots,
> re-loads, restarts.
>
> Apparently there's something i'm not getting thru my thick skull about
> packet filtering. Could someone explain to me in text (no diagrams) how a
> packet is evaluated and then processed tru the chains, also what is done and
> not-done any more after a packet has passed thru a chain. Somehow i have the
> idea this config works from the lan to the outside but not from the outside
> to the lan or something.
>
> Any good resources, tips, explanations are welcome. I'm to dumb for this i
> guess.
Hi,
Your not dumb, you use Debian don't you? :)
Perhaps check out www.tldp.org for how-to's on netfilter/iptables stuff.
To be basic, anything destined/orginating for/from your box will hit the INPUT
and OUTPUT chains. Thats it. Anything that is destined somewhere else. Will
only hit your FORWARD chain. This is for your default "filter" table.
The "mangle" and "nat" tables are for other stuff. Usually nat is for
masquerading. Check out debian's ipmasq package for easy setup.
Good luck,
Cheers,
Mike
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