[Tfug] A little help here sharing my cellmodem connection...?

[Ronald Sutherland]

On Sat, Oct 4, 2008 at 8:03 AM, Robert Hunter <hunter at tfug.org> wrote:
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> On Sat, Oct 04, 2008 at 01:50:10AM -0700, Jim March wrote:
>> So I'm thinking I ought to do old-fashioned IP tables, or use a
>> firewall app of some sort.
>
> Check out arno-iptables-firewalls.  The debian package comes with
> debconf setup, which is adequate for a basic NAT configuration.  If
> you want to do more advanced things (e.g., port forwarding, DMZ, etc.),
> the configuration file is easy to understand and modify.  I've been
> using it for a couple years, and I like it much better than some of
> other choices, such as firestarter (blech).
>
> - --Rob
Yep... As a quick reference: The upstream port (aka gateway) needs to
be set with the IP address where the data will flow out (so the USB
cell link address I guess). Then decide on a different IP
address/subnet for the LAN port. Then use Network Address Translation
to rout the subnet addresses on the LAN port to the USB device. NM7
can probably do this, but I would not have a clue, ShoreWall,
FireStarter, and even Ubuntu's "ufw" can be used to setup iptables to
do that. One thought is to only use one of these tools, because they
will likely step on each others toe.

Sorry if that's not much to go on, but good luck on your efforts.