DSL line and local network - is it necessary to use 2 nics ?

Hi,

sorry for dummy security question...

What is the difference between 2 nics setup (one to ADSL modem and other to
local network) or 1 nic setup (one to ADSL modem over PPP and gateway at the
same time for connection sharing) from security standpoint ?

Regards,

R.

On 2004-12-05, Robert Rozman <rozman@fri.uni-lj.si> wrote:
> Hi,
>
> sorry for dummy security question...
>
> What is the difference between 2 nics setup (one to ADSL modem and other to
> local network) or 1 nic setup (one to ADSL modem over PPP and gateway at the
> same time for connection sharing) from security standpoint ?
>
IP spoofing. Its impossible to seperate traffic whether traffic came from
the internet via your ADSL modem and traffic that came from your local
network. Of course its likely that local IP addresses came from the local
network and were not spoofed from the internet however you cannot guarentee
it with the physically seperation that two NICs give you.

If you are NAT'ing then at least you can do some kind of firewalling, if you
are using public routable IP's then forget it, that box might as well not be
there.

As network cards are £10 (or if you are that way inclined, $10-$20) there
really is little excuse why you should only have one, unless you have a 1/2U
case or something of course.

Cheers

Alex