Re: NATLL6 [was Re: Forwarding Packets With Link Local Destination Addresses]

Fernando Gont <> Fri, 08 January 2021 20:25 UTC

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Subject: Re: NATLL6 [was Re: Forwarding Packets With Link Local Destination Addresses]
To: Brian E Carpenter <>, Alejandro Acosta <>,
References: <> <> <>
From: Fernando Gont <>
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Date: Fri, 8 Jan 2021 16:51:12 -0300
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On 8/1/21 16:37, Brian E Carpenter wrote:
>>> I interpret this statement to include packets that contain routing headers. For example, it forbids an SRv6 packet whose final segment has a locator that begins with FE80.
>>    In LACNIC we ran a project called Natmeter [1] for about 2 years, we obtained a lot of interesting data during this period [2].
>>    The case is the following, we detected some end-user devices with only Link Local addresses (exactly, no GUA nor ULA) that were successfully natted and using the web.
>>    Is it ok?, do you consider it as a forwarding of a packet? was it a crazy result? (we saw few samples of this)
> NAT66 is not defined and not recommended, so there really isn't an answer to your questions. I can't think of a reason why such a hack wouldn't work, though. As long as the LL address is translated, it will not escape from the LAN.

I would expect that something else (other than IPv6 NAT) is going on. IN 
that sense, it would be interesting to know more details about the 
methodology they employ to measure the use of NATs.


Fernando Gont
SI6 Networks
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