nanog mailing list archives

Re: Is NAT can provide some kind of protection?


From: david raistrick <drais () icantclick org>
Date: Wed, 12 Jan 2011 15:53:07 -0500 (EST)

On Wed, 12 Jan 2011, Chris Adams wrote:

Yes, they do.  NAT requires a stateful firewall.  Why is that so hard to
understand?

Um. No. NAT requires stateful inspection (because NAT needs to maintain a state table), but does not require a stateful firewall. You can (and many CPE appliances do/did) have no firewall, or stateless firewall in front of NAT.


All NAT does is give you an implied deny-all-inbound rule, but doesn't, in and of itself, prevent someone probing open (configured by you or the vendor) ports that are forwarded or on the device. Or from having unfettered inside access of 1 internal IP if you NAT all external ports to an internal IP.




--
david raistrick        http://www.netmeister.org/news/learn2quote.html
drais () icantclick org             http://www.expita.com/nomime.html



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