Re: DNSBL and IPv6

On 20 Oct 2012, at 05:41, Mikael Abrahamsson <[email protected]> wrote:

> On Fri, 19 Oct 2012, Steve Atkins wrote:
> 
>> (I'm betting that "mask the bottom 64 bits before querying" would work just fine, but I don't think we have enough v6 space in use yet to say for sure.)
> 
> I agree. Although I believe some ISPs will put multiple customers in a single /64, this is mostly going to be dynamic customers anyway (multiple laptops on a wifi for instance), and those I would imagine are treated with the same policy so it doesn't really matter. Per /64 handling is a reasonable tradeoff between granularity and practicality in my mind.

A /64 basis seems to be the most sensible starting point, from which one could 'suck it and see'.

In client scenarios where multiple users share a /64, e.g. in a wifi hotspot, then they are probably sharing one public IPv4 address with IPv4 NAT now.  

In data centre scenarios, what do we expect there? It's not clear from draft-lopez-v6ops-dc-ipv6-03.  It may depend on whether the hosting is physical or virtual? The allocated prefix is likely to be quite stable.

In home networks, the current trend in Europe seems to be /60 to /56, though some offer /64 or /48.  In some cases the equipment can only handle /64 now, but expect that to shift to /56 or /60 later.  The work on draft-ietf-homenet-arch-05 expects the ISP to offer multiple /64's.  It seems many ISPs will vary the prefix offered over time much as with dynamic IPv4 addresses today.  In some countries, that's apparently a legal requirement.

In enterprises, /48, and more likely to be stable.

Our evidence from incoming spam is that most of it comes via dual-stack list servers.  There's very little evidence of spam coming from autoconfigured addresses that would indicate client senders.

Tim