On 04/22/2010 10:18 PM, Matthew Kaufman wrote:
Owen DeLong wrote:
On Apr 22, 2010, at 5:55 AM, Jim Burwell wrote:
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On 4/22/2010 05:34, Simon Perreault wrote:
On 2010-04-22 07:18, William Herrin wrote:
On the other hand, I could swear I've seen a draft where the PC picks up random unused addresses in the lower 64 for each new outbound connection for anonymity purposes.
That's probably RFC 4941. It's available in pretty much all operating systems. I don't think there's any IPR issue to be afraid of.
Simon
I think this is different. They're talking about using a new IPv6 for each connection. RFC4941 just changes it over time IIRC. IMHO that's still pretty good privacy, at least on par with a NATed IPv4 from the outside perspective, especially if you rotated through temporary IPv6s fairly frequently.
4941 specified changing over time as one possibility. It does allow for per flow or any other host based determination of when it needs a new address.
Owen
But none of this does what NAT does for a big enterprise, which is to *hide internal topology*. Yes, addressing the privacy concerns that come from using lower-64-bits-derived-from-MAC-address is required, but it is also necessary (for some organizations) to make it impossible to tell that this host is on the same subnet as that other host, as that would expose information like which host you might want to attack in order to get access to the financial or medical records, as well as whether or not the executive floor is where these interesting website hits came from.
Does your nat box reset or non-determisitically rewrite the ttl on the outgoing packet? ALGs are dramatically better topology hiding devices...
Matthew Kaufman