RE: Security gain from NAT

["Howard C. Berkowitz" <hcb () netcases net>]

I'm sure everyone understands the underlying principle, but I'm constantly
making the point that even the best firewall is not a total security
solution. Forget antivirus, IDS, host authentication, etc., and just look on
the perimeter.

At least four device types lead inside from the DMZ:
   NAT
   Firewalls of various flavors
   VPN concentrators/security gateways
   Rate-limiting anti-DOS devices to protect host-to-host encryption

For small and medium enterprises, these functions might, as an
implementation choice, reside in the same box; NAT is most likely to coexist
with firewalling or VPN concentration. The latter gets a little Zen-ish if
the VPN concentrator acts as a separately addressed proxy anyway.

-----Original Message-----
From: owner-nanog () merit edu [mailto:owner-nanog () merit edu] On Behalf Of Sam
Stickland
Sent: Monday, June 04, 2007 3:04 PM
To: Joe Abley
Cc: Jim Shankland; Owen DeLong; NANOG list
Subject: Re: Security gain from NAT


Joe Abley wrote:
> On 4-Jun-2007, at 14:32, Jim Shankland wrote:
>
> > Shall I do the experiment again where I set up a Linux box
> > at an RFC1918 address, behind a NAT device, publish the root
> > password of the Linux box and its RFC1918 address, and invite
> > all comers to prove me wrong by showing evidence that they've
> > successfully logged into the Linux box?
>
> Perhaps you should run a corresponding experiment whereby you set up a 
> linux box with a globally-unique address, put it behind a firewall 
> which blocks all incoming traffic to that box, and issue a similar 
> invitation.
>
> Do you think the results will be different?
I fear a somewhat more cynical person could interpret the results of 
such an experiment to mean that NAT is as good as a firewall ;)

S