Re: ADSL

["alcinababe" <alcinababe@xxxxxxx>]

--- In ukha_d@xxxxxxx, Simon Kennedy <stonewolfsoft@y...> wrote:

> Thanks Chris but the answer is still eluding me. Are
> you saying that an IPCop based firewall + an ADSL
> modem does less than an ADSL router and that I would
> need a router as well as an IPCop firewall?
>
> I was under the impression that
> ADSL Modem + IPCop firewall = ADSL Router
>
> At least that's what they seem to imply here
> http://www.mini-itx.com/projects/ipcop/

The short (and unhelpful) answer is: depends on the ADSL router!

Try to think of it in terms of signal and where it's going.  This is
not entirely accurate, but may help with the mental picture.  You have
a phone signal coming into your house via the BT socket.  This signal
is dealt with by a modem device and turned into a signal that a
computer can understand.  But only one computer.  One signal, one
computer.  The very basic adsl connection is one computer attached to
a modem attached to a BT socket:

BT -> modem -> single computer

Fine.  But you want more than one computer to connect to the BT
socket.  In order to do this you need a router device.  A router
'routes' the signal to/from different computers to/from the modem
device.  It utilizes some clever wizardry (usually NAT) that means it
can remember which computer asked for which web page, so if two people
are surfing at the same time they don't receive each other's web
pages!  This is usually done in conjunction with a hub device (you
gotta have something to plug all your cables into!)

So...you now have:

BT -> modem -> router -> hub -> lots of computers

But what about those nefarious hacker script kiddies?  You want a
firewall.  This usually goes between the router and the modem:

BT -> modem -> firewall -> router ->hub -> lots of computers

That's your basic model.  The problem I think you're having is that a
lot of products incorporate more than one of those devices in that
chain.  For example, ipcop is a software firewall *and* router (ie.
you still need a hardware modem and a hardware hub at either end).
Some of the hardware (one box) adsl routers comprise modem, router,
firewall *and* hub (albeit usually only 4 ports).  Some adsl routers
comprise only the router and hub (you need your own modem and
firewall) etc.  If you want to use ipcop the model is:

BT -> modem -> IPCop -> hub -> lots of computers

If you have a basic adsl router (modem/router/firewall) the model is:

BT -> adsl box -> hub -> lots of computers

If you have an all-in-one wonder box (router/modem/firewall/hub):

BT -> wonder box -> lots of computers

So, as you can see, it all depends on what's actually inside the adsl
router box.  I hope this makes sense!
Alcina