Re: How NAT reacts on table flood ?

From: Robert E. Lee (robert@dyadsecurity.com)
Date: Tue Jul 11 2006 - 13:45:12 EDT


On Tue, 11 Jul 2006 15:15:12 +0200
"Norbert François" <norbertlike@gmail.com> wrote:
> I was wondering how the NAT reacts when its translation table is
> full... For example, suppose that you've 100 computers behind a NAT
> (University) and one (or more) of them engages purposely a lot of
> connexion, in order to fill the NAT table, what will occur ?

It will no longer complete new connections. In most cases the already established connections will continue to function, but in some cases the device will stop passing traffic altogether.

Pretty easy to replicate this one from home if you have a linksys/smc/whatever nat box at your house, grab your favorite port scanner and scan the internet at a high speed. It should kill your NAT box rather quickly as it has to account for connection status for every attempted connection.

Robert

-- 
Robert E. Lee
Chief Information Officer
http://www.dyadsecurity.com
 
phone: (949) 394-2033
fax  : (949) 486-6601
email: robert@dyadsecurity.com
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