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Re: DNS and NAT (was: DNS and CheckPoint)
From: Valdis.Kletnieks () vt edu
Date: Fri, 11 Jul 2008 11:51:42 -0400

On Fri, 11 Jul 2008 11:01:33 EDT, Thomas Cross said:

    Thanks for testing this. A number of other readers wrote me privately
confirming your result with linux ipchains. I'm not sure what ipchains does
when it encounters a collision, but in general I think this is a good
strategy. You'd have to have many thousands of simultaneous UDP
transactions in order for randomly selected source ports to be colliding
frequently enough for it to present a substantial problem.

Birthday paradox strikes again.

With 64K source ports, you'll have collisions over 1% of the time at only 1024
in use. With 8K in use, you're hitting collisions 12% of the time.

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