David Sommerseth wrote:
> On 06/12/10 15:29, Todd Rinaldo wrote:
>> On Dec 6, 2010, at 5:27 AM, David Sommerseth wrote:
>>
>>> On 05/12/10 14:21, Tom H wrote:
>>>> On Sun, Dec 5, 2010 at 8:13 AM, RedShift <redshift@xxxxxxxxxx> wrote:
>>>>> On 12/05/10 12:50, Rudi Ahlers wrote:
>>>>>> (http://www.internetnews.com/infra/article.php/3915471/IPv4+Nearing+Final+Days.htm),
>>>>> Haven't switched yet, I have IPv6 at home using sixxs.
>>>>>
>>>>> I can't even figure out what address ranges are reserved for private use, is there even such a concept in IPv6?
>>>> I think that site-local ("fec0:: - fef::") is the ipv6
>>>> more-or-less-equivalent of ipv4 private addresses.
>>> Yes, that's correct and it is deprecated.
>>> <http://www.ietf.org/rfc/rfc3879.txt>
>>>
>>> With IPv6 there is plenty of addresses for everyone so you basically use
>>> your own assigned official IPv6 address space and setup your own private
>>> /64 net and block that subnet in your firewalls.
>>>
>>> Another thing, there is no NAT and it will not be implemented as we know
>>> it in IPv4. To call NAT a security feature is also a faulty
>>> understanding. As NAT only prevents access from outside to some
>>> computer inside a network which is NAT'ed. This restriction and
>>> filtering is the task of the firewall anyway, which does the NAT anyway.
>>>
>>> NAT basically just breaks a lot of protocols and enforces complex
>>> firewalls which needs to understand a lot of different protocols to be
>>> able to do things correctly. Which often do not work as well as it could.
>>>
>> I've heard this before but It's always confused me. Admittedly I
>> haven't had a chance to look at the spec. If we're saying that
>> everyone's going to have the same private subnet, then we're saying
>> that all the private subnets are going to have to be NAT-ed
>> aren't they?
>
> This can be a bit confusing, especially if you see this with "IPv4
> eyes". In IPv6, it basically is no such things as a private subnet (range).
>
> When you contact your ISP to get a IPv6 subnet, they will most probably
> give you a /48 network. That means you will have a IPv6 prefix which is
> unique. That is a reference to all _your_ IPv6 networks.
>
> Then you will normally segment this /48 subnet into more /64 networks.
> A /48 subnet gives you 65536 /64 networks. So the IPv6 prefix will be
> something like:
>
> aaaa:aaaa:aaaa:bbbb::/64
>
> the 'aaaa:aaaa:aaaa' part is the prefix your ISP will provide you, and
> this is the first 48bits of the IPv6 address. The 'bbbb' part is up to
> you to decide what will be, and that's the next 16 bits of the address
> scope. So 48 + 16 = 64 bits. And 2^16 = 65536.
>
> And this is all you need to know about IPv6 addressing. Really! That's
> it. No network addresses, no broadcast addresses. Just pure usable
> IPv6 addresses.
>
> (You may of course make even more subnets below /64, but that's usually
> not recommended at - especially with auto-configured networks)
>
> So then ... the next phase. As everyone who gets a /48 nets should have
> it flexible enough to setup private networks, the firewall just needs to
> block completely in-going traffic to a /64 net defined by the admins as
> private. It can further be decided if this /64 net should have access
> to IPv6 addresses outside this local network. Again this is just a
> firewall rule and nothing more - allow or reject/drop.
>
> And then, the former proposed site-local subnet makes pretty much no
> sense, as IPv6 does not support NAT. As this network would not be able
> to communicate across a router/firewall. This subnet (fec0:: - fef::)
> should not be routed anywhere. And without NAT, it can't escape the
> subnet at all anyway.
>
> So, spending one or two or 100s /64 subnets with public IPv6 addresses
> which is completely blocked in a firewall will serve exactly the same
> purpose as a site-local subnet. But this /64 net may get access to the
> Internet *if* allowed by the firewall. This is not possible with
> site-local at all. And of course, this is without NAT in addition.
>
> I hope this made it a little bit clearer.
Clear as mud. If I understand you correctly, I have to say that IPv6 is
broken by design. I have a double handful of computers on my home
network. Each of them needs access to the Internet to get updates to the
OS and various applications. However, I do *NOT* want each and every one
of them to show up as a unique address outside of my network. With IP4
and m0n0wall running as the NAT, they are all translated to the single
IP address that Roadrunner assigned to my Firewall. I need to continue
that mapping. If IPv6 cannot do that, then I hope Time-Warner continues
to ignore it and stays with their current address structure.
Bob McConnell
N2SPP
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