[e2e] 100% NAT - a DoS proof internet

Christian Huitema huitema at windows.microsoft.com
Mon Feb 13 10:19:51 PST 2006

> Worms don't come in directly to the IP's that often, they spread
> using email, broswers, and other applications and some unknowing user
> simply starting applications it should not be running. Host-based
> firewalls do a wonderful job here already. Of course there are some
> which scan semi-randomly but the effect is lower than a email
> a jucky picture of some teen celebrity.

Jeroen is right. If you look at "DOS topology", there is very little
difference between an external firewall (Jon's NAT) and a host firewall.
It is just a different way to build the distributed system.

Jon may object that, from a practical point of view, an external box is
"more secure" since it is small, does exactly one thing, does it well,
etc. But on the other hand, the small box is a commodity component, sold
with a razor thin margin. Even small boxes do have bugs, and it is much
easier for users to apply a patch downloaded from Windows Update than to
try to re-flash the firmware of a router.

I don't know whether Jon's "rendezvous on time" proposal actually solve
DOS issues, but it is interesting for other reasons. It enables "private
rendezvous in a public world". The parties conspire to publish a name
(the rendezvous point) that changes frequently and cannot be easily
guessed by third parties. That is indeed quite interesting, because now
only authorized peers can track someone's presence on the internet.

Of course, private naming is only one element in the privacy puzzle. For
example, changing the name is not very interesting if the IP address
remains constant or if external sites can track someone's presence using

-- Christian Huitema

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