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Re: How do I keep an inet6 address from being added to an interface?


On Thu, May 6, 2010 at 7:56 AM, Steven Bellovin <> 
> On May 5, 2010, at 11:59 07PM, Arnaud Lacombe wrote:
>> Hi,
>> On Wed, May 5, 2010 at 4:14 PM, Matthew Mondor 
>> <> wrote:
>>> On Wed, 5 May 2010 10:10:43 -0700
>>> Dennis Ferguson <> wrote:
>>>> Hello,
>>>> I want to configure an interface up without any protocol addresses
>>>> being added to (or protocols enabled on) the interface.  I see,
>>>> however, that the act of typing `ifconfig rtk0 up' results in
>>>> an ipv6 address being added to the interface, which I assume
>>>> also enables ipv6 protocol processing.  How do I make it stop
>>>> doing that?
>>> Hmm after looking at sysctl(8) net.inet6 stubs and in6_ifattach.c there
>>> seems to be no option that I see for that in netbsd-5.  It's part of
>>> the ipv6 standard that interfaces have an automatic link-local address,
>>> and that address can only be used on the local network, but I guess
>>> that it could be legitimate for some administrator to not want a
>>> link-local address configured.
>> actually, there is a way, `ip6_auto_linklocal', but it is not made
>> public. Maybe could we expose it in the sysctl tree ?
> Does that work on per-interface?
> I've often wanted such a feature: a way to ensure that NetBSD's kernel 
> neither sends or acts on *any* packet received on certain interfaces.
No, it is done when the interface is attached, so before any user
intervention is possible; if I'm not mistaken. This would make the
sysctl useless, so this would have to be a hardcoded default.

 - Arnaud

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