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Re: Security gain from NAT (was: Re: Cool IPv6 Stuff)

  • From: Matthew Palmer
  • Date: Mon Jun 04 20:58:57 2007

On Mon, Jun 04, 2007 at 04:27:14PM -0700, David Schwartz wrote:
> > I posit that a screen door does not provide any security. A lock and
> > deadbolt provide some security.  NAT/PAT is a screen door.
> > Not having public addresses is a screen door.  A stateful inspection
> > firewall is a lock and deadbolt.
> This is a fine piece of rhetoric, but it's manifestly false and seriously
> misleading.
> I have a cluster of Windows machines at my store with no networking security
> at all. They're behind NAT/PAT and nothing else.

Can you give us technical details about how you're doing NAT/PAT without any
form of stateful packet inspection?  I'm sure we'd all be most interested.

If it turns out that you are, in fact, using stateful inspection, then
you've got that lock and deadbolt installed, but haven't noticed it behind
the screen door.

> I can give you the root password to a Linux machine running telnetd and
> sshd. If it's behind NAT/PAT, you will not get into it. Period.
> I can give you the administrator password to a Windows machine with file
> sharing wide open. If it's behind NAT/PAT, you will not get into it. Period.
> The only ways into these machines would be if the NAT/PAT device were
> misconfigured, another machine on the secure network were compromised, or
> another gateway into the secure network was set up. Guess what? All of these
> things would defeat a stateful inspection firewall as well.

Which means that -- tada! -- NAT/PAT isn't giving you anything that the
stateful inspection firewall isn't.

> Are there things most stateful inspection firewalls can do that NAT/PAT does
> not do? Definitely. Are those things valuable and in some cases vital?
> Definitely. So why lie and distory what NAT/PAT actually does do? A large
> class of security vulnerabilities require the attacker to reach out to the
> machine first, and NAT/PAT stops those attacks completely.

As does stateful inspection.

Duck season!

- Matt

when SuSE are doing better than you at publishing the tools they use, it's a
hint that maybe you suck.
		-- Andrew Suffield, debian-devel