Security gain from NAT

Dave Israel davei at
Mon Jun 4 19:22:11 UTC 2007

Valdis.Kletnieks at wrote:
> On Mon, 04 Jun 2007 11:32:39 PDT, Jim Shankland said:
>> *No* security gain?  No protection against port scans from Bucharest?
>> No protection for a machine that is used in practice only on the
>> local, office LAN?  Or to access a single, corporate Web site?
> Nope. Zip. Zero. Ziltch.  Nothing over and above what a good properly
> configured stateful *non*-NAT firewall should be doing for you already.

What the firewall *should* be doing?  The end devices *should* not need 
protection in the first place, because they *should* be secure as 
individual devices.  But they are not.  So you put a firewall in front 
of them, and that device *should* give them all the protection they 
need.  But sometimes, it doesn't.  So you make end devices unaddressable 
by normal means, and while it shouldn't give them more security, it 
turns out it does.  No matter how much it shouldn't, and how much we 
wish it didn't, it does.

The difference between theory and practice is that in theory, there is 
no difference, but in practice, there is.

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