From: Dobbins, Roland Sent: Wednesday, January 05, 2011 7:19 PM To: Nanog Operators' Group Subject: Re: NIST IPv6 document
On Jan 6, 2011, at 10:08 AM, Joe Greco wrote:
I don't believe that host-/port-scanning is as serious a problem as you seem to think it is, nor do I think that trying to somehow prevent host from being host-/port-scanned has any material benefit in terms of security posture, that's our fundamental disagreement.
It will be a problem if people learn they can DoS routers by doing it by maxing out the neighbor table.
If I've done what's necessary to secure my hosts/applications, host- /port-scanning isn't going to find anything to exploit (overly- aggressive scanning can be a DoS vector, but there are ways to ameliorate that, too).
I don't think you are understanding the problem. The problem comes from addressing hosts that don't even exist. This causes the router to attempt to find that host. The v6 equivalent of ARP. At some point that table becomes full of entries for hosts that don't exist so there isn't room for hosts that do exist.
This whole focus on sparse addressing is just another way to tout security-by-obscurity. We already know that security-by-obscurity is a fundamentally-flawed concept, so it doesn't make sense to try and keep rationalizing it in various domain-specific instantiations.
No, it was designed to accommodate EUI-64 addresses which are to replace MAC-48 addresses at layer2. We currently create an EUI-64 address out of a MAC-48 in many cases during SLAAC but at some point the interfaces will be shipping with EUI-64 addresses. The world is running out of MAC-48 addresses. So at some point the "MAC" address will be the host address and it will be 64-bits long. It has nothing to do with "security by obscurity".