Subject: [Fwd: Re: About IPv6 private address]

From: blue <[email-masked]>
Date: Mon, 04 Feb 2008 15:43:49 +0800

Subject: Re: About IPv6 private address
From: blue <[email-masked]>
To: Thomas Herbst <[email-masked]>
Date: Mon, 04 Feb 2008 14:25:07 +0800

Even by mDNS or LLMNR, the device need to reply the queried name, such 
as "gateway.local.", with a valid IPv6 address except link-local address 
since DNS record could not allow link-local address to be carried. 
Without any configuration, there's no IPv6 address available besides 
link-local address. Or you suggest using the combination of Unique Local 
IPv6 address and mDNS?

Thanks.
BR,
Yi-Wen

Thomas Herbst wrote:

>Couldn't this be done with a name via m-dns or something similar?
>
>tom
>
>At 08:01 PM 2/3/2008, Fred Baker wrote:
>  
>
>>This is straight off the top of my head, without a lot of thinking.  
>>But suppose the device took a random (as random as it could come up  
>>with) ULA and decided to use it locally, and became the "router",  
>>which is to say, issued an RA? That would be needed for the host to  
>>form an address anyway. The host could then connect to the local  
>>router, whose address it by definition knows (it is the only foreign  
>>address in its neighbor database). The router could discard the ULA  
>>after configuration completed and it had a prefix issued by its ISP.
>>
>>Tom and Ole, adding you to the thread. Do you have suggestions?
>>
>>On Feb 4, 2008, at 5:45 AM, blue wrote:
>>
>>    
>>
>>>Fred Baker wrote:
>>>      
>>>
>>>>On Feb 4, 2008, at 4:59 AM, blue wrote:
>>>>        
>>>>
>>>>>I want to ask if there's any reserved private IPv6 address? I  
>>>>>know  RFC4193 has defined Unique Local IPv6 Unicast Addresses,  
>>>>>which is  used to replace deprecated site-local address. However,  
>>>>>in user's  perspective, a device will need a well-known address,  
>>>>>such as  192.168.1.1 in IPv4, for a customer to connect to  
>>>>>without any  configuration. In RFC 4193, the address' "global ID"  
>>>>>is generated  randomly, and the address could not be known in  
>>>>>advance.
>>>>>          
>>>>>
>>>>No, there is no such "well known" address. Are you thinking of   
>>>>configuration purposes, such as a Linksys box uses - you http the   
>>>>magic address and configure it?
>>>>        
>>>>
>>>Dear Fred:
>>>
>>>Yes, users need to configure our device via http, and if there's no  
>>>well-known IPv6 address, how do users know which address to connect  
>>>to? I have thought about a pre-configured link-local address;  
>>>however, browsers such as Firefox does not support link-local  
>>>address. Any suggestions?
>>>
>>>BR,
>>>Yi-Wen
>>>      
>>>
>
>
>  
>

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Mon, 4 Feb 2008 16:00:39 +0100

On 4 feb 2008, at 8:43, blue wrote:

> Even by mDNS or LLMNR, the device need to reply the queried name,  
> such as "gateway.local.", with a valid IPv6 address except link- 
> local address since DNS record could not allow link-local address to  
> be carried.

Is there any particular reason we're reinventing this specific wheel  
for which excellent implementations exist? In my webbrowser I can look  
under "bonjour" (sometimes mistakenly called mDNS) and get a list of  
printers on the local network.

---

From: james woodyatt <[email-masked]>
Date: Mon, 4 Feb 2008 09:52:31 -0800

On Feb 4, 2008, at 07:00, Iljitsch van Beijnum wrote:
>> local address since DNS record could not allow link-local address  
>> to be carried.
>
> Is there any particular reason we're reinventing this specific  
> wheel for which excellent implementations exist? In my webbrowser I  
> can look under "bonjour" (sometimes mistakenly called mDNS) and get  
> a list of printers on the local network.

On top of that, it already works, today, with IPv6-- which is a win  
when the browsing host has multiple network interfaces, as most  
personal computers do these days.  IPv6 link-local addresses are  
scoped to the interface, so addressing conflicts are completely avoided.

Some people just want to make things harder than necessary to use, I  
guess.

--
james woodyatt <[email-masked]>
member of technical staff, communications engineering

---

From: Mark Smith <[email-masked]>
Date: Tue, 5 Feb 2008 06:47:32 +1030

On Mon, 4 Feb 2008 09:52:31 -0800

> Some people just want to make things harder than necessary to use, I  

Well, not everybody has or will have Apples, so they won't have Bonjour
aware clients/browsers. There does need to be alternative methods.

You're right though, service / device location is old school, Novell
Netware and Appletalk got that sorted out years ago, and SLP and
Bonjour seem to me to mainly be IETF versions of their techniques.

Regards,
Mark.

---

From: Joe Abley <[email-masked]>
Date: Mon, 4 Feb 2008 16:41:54 -0500

> aware clients/browsers. There does need to be alternative methods.

As far as I know, though, Bonjour isn't limited to Apple devices. It's  
definitely available on free *ix platforms (and I say "definitely"  
because I've used it) and apparently available on Windows too  
("apparently" because I have not had a reason to use Windows since  
about 1995).

So it doesn't seem reasonable to discount this as a reasonable  
mechanism on the grounds that "not everybody uses Apple products".

Joe

---

From: Mark Smith <[email-masked]>
Date: Tue, 5 Feb 2008 20:43:33 +1030

Hi Joe,

On Mon, 4 Feb 2008 16:41:54 -0500

> mechanism on the grounds that "not everybody uses Apple products".

I'm certainly not against it, just pointing out that unlike web
browsers, bonjour clients aren't anywhere near as common, so it isn't
quite yet a universal way of performing service discovery (and neither
is SLP of course).

Regards,
Mark.

---

From: Jeroen Massar <[email-masked]>
Date: Mon, 04 Feb 2008 23:53:14 +0100

Joe Abley wrote:
> ("apparently" because I have not had a reason to use Windows since about 
> 1995).
> 
> So it doesn't seem reasonable to discount this as a reasonable mechanism 
> on the grounds that "not everybody uses Apple products".

IMHO mDNS definitely is rather good answer to the problem of "end-user 
adds a router to his home network" or for that matter a large number of 
similar issues (eg "user adds Camera", "user adds IPv6 enabled Fridge" 
and many others of those things, "user adds IP-enabled F16" etc... :)

uPNP offers a similar solution of course, as it announces the devices + 
capabilities + url for configuration on the local network.

Couple of things that can be done here:
  - check that there is already a router on the link
    ping6 ff02::2, reply? -> another one there
    no reply? -> you are the first one
    when one is the first one or there is no RA
    -> create a ULA + announce it
    otherwise use the existing prefix

Then either:
  - use mDNS to announce the name of the host
    (include MAC/serial to make it unique)
  - use RA/DHCPv6 to provide DNS server address
  - create a captive portal on port 80, this portal
    is the configuration interface.

In general of course, why would such a device need to be configured 
anyway, except for "allow inbound connections", which I guess should be 
off per default to protect the innocent.

Greets,
  Jeroen