nanog mailing list archives

Re: Is NAT can provide some kind of protection?


From: Owen DeLong <owen () delong com>
Date: Wed, 12 Jan 2011 11:57:34 -0800


On Jan 12, 2011, at 11:21 AM, Paul Ferguson wrote:

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On Wed, Jan 12, 2011 at 11:09 AM, Owen DeLong <owen () delong com> wrote:

No, NAT doesn't provide additional security. The stateful inspection that
NAT cannot operate without provides the security. Take away the
address mangling and the stateful inspection still provides the same
level of security.


There is a least one situation where NAT *does* provide a small amount of
necessary security.

Try this at home, with/without NAT:

1. Buy a new PC with Windows installed
2. Install all security patches needed since the OS was installed

Without NAT, you're unpatched PC will get infected in less than 1 minute.

Wrong.

Repeat the experiment with stateful firewall with default inbound deny and no NAT.

Yep... Same results as NAT.

NAT != security. Stateful inspection = some security.

Next!!

Owen



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