> Because the adsl modem is set to bridge mode the only way in and out of
> it is by PPPoE, right? So that means also that the only way for someone
> from the outside to access the network is via the PPPoE client?
> The only machine with a PPPoE client installed is the firewall, and all
> of the other machines use the firewall as their gateway to the net.
> 
I have never tried what you are proposing. I really don't like the idea.
It looks to me that you ^may^ have network issues, if you are going to non
public ip addresses.


> Why would that not be secure?
> 
Ideally bridge mode should have a direct connection to the firewall.
The art work below would not entirely protect you against those "bad
guys" ;). If by some sheer dumb luck someone exploits your DSL Modem
they have a potential to own your entire network. With the below design
what is going to do NAT? Really your work stations need to hide behind
a firewall. Also ideally a firewall is a machine that is not used for
day to day use. For a secure network design there are a few docs that
will help you visit http://www.tldp.org/HOWTO/Firewall-HOWTO-3.html


> > > >       ADSL Modem    Firewall   Local Workstations
> > > >           |            |          |          |
> > > >           +-----H------+----U-----+----B-----+
> > > >
Really your network design should look a little like below to ensure
security.

        +----------+    +--------+      +---+   +------------+
        |ADSL Modem|----|Firewall|------|Hub|---|Workstations|
        +----------+    +--------+      +---+   +------------+

You firewall should be a bare bones system. You could also use products
like shorewall, astro, Mandrakes MNF (apparently a spinoff on shorewall)


-- 
Regards,

Kevin Saenz
 
Spinaweb
I.T consultants
 
Ph: 02 4620 5130
Fax: 02 4625 9243
Mobile: 0418455661
Web: http://www.spinaweb.com.au

-- 
SLUG - Sydney Linux User's Group - http://slug.org.au/
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