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Date: Thu, 12 Feb 2009 11:07:28 -0500
From: Steve Bertrand <steve@ibctech.ca>
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To: Bruce Cran <bruce@cran.org.uk>
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Cc: freebsd-net@freebsd.org
Subject: Re: IPv6 autoconfiguration fails
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Bruce Cran wrote:
> On Thu, 12 Feb 2009 09:56:29 -0500
> Steve Bertrand <steve@ibctech.ca> wrote:
> 
>> Bruce Cran wrote:
>>> [forwarding from current@]
>>>
>>> I recently reinstalled -current on my laptop and have started seeing
>>> IPv6 autoconfiguration failing.  I have two interfaces re0 and
>>> ath0: re0 is plugged in and gets an address via DHCP while I'm not
>>> using wireless at the moment so ath0 remains unconfigured.  However
>>> it seems the IPv6 autoconfiguration tries to use ath0 instead of
>>> re0.
>> There is a very similar issue over on -questions.
>>
>> Does it help if you disable rtadv on ath0?:
>>
>> # ndp -i ath0 -- -accept_rtadv
> 
> It didn't help, but your last message on -questions made me realise I'd
> made the classic mistake of enabling a firewall but not allowing inbound
> icmp[6] packets.  As soon as I'd reloaded the rules things started
> working again.

Good stuff.

Just a note that blocking inbound ICMP will break Path MTU discovery,
which, if not considered, can be quite difficult to troubleshoot.

Cheers,

Steve