Re: Firewall definition

From: Todd H. (comphelp_at_toddh.net)
Date: 12/26/03 

Date: 26 Dec 2003 01:31:03 -0600

stuarth@ecs-tech.com (Stuart Halliday) writes:

> Is a NAT Router technically a Firewall?

A simple router with NAT turned on and configured to cheerfully pass
all traffic is not a firewall. It's a router with network address
translation enabled and nothing more.

> A lot of Router Manufacturers seem to list NAT as a Firewall feature
> when selling ADSL/Cable Routers.

They do because the NAT feature is useful to home users who with to
allow a multiplicity of computers share a single IP address given from
a broadband provider. The NAT itself does provide a modicum of
security by translating address domains and making it more difficult
to attack a single selected internal host from the outside.... but NAT
itself does not a firewall make.

> I say it's a byproduct of how NAT works rather than really a Firewall.
>
> I say to be a Firewall means its must actively probe packets, block
> suspicious ones and alert the user.
>
> A colleague says just a Router with NAT is a Firewall.
>
> Who's right? :-)

Depends on who you ask, but I'd say you've got a better handle on it
than your colleague.

To me, a firewall appliance is a router with at least two interfaces
that is configured to restrict incoming and outgoing traffic to a
defined set of allowable traffic.

A personal firewall would be a piece of software running on a general
purpose host that restricts incoming and outgoing traffic based on a
defined set of allowable traffic.

Best Regards, 

-- 
Todd H.
http://www.toddh.net/