Date: Thu, 23 Aug 2012 17:55:47 +0900 From: Hajimu UMEMOTO <ume@FreeBSD.ORG> To: Andrey Chernov <ache@FreeBSD.ORG> Cc: svn-src-head@FreeBSD.ORG, svn-src-all@FreeBSD.ORG, src-committers@FreeBSD.ORG Subject: Re: svn commit: r239356 - head/sbin/dhclient Message-ID: <ygeipcaasx8.wl%ume@mahoroba.org> In-Reply-To: <20120823044137.GA7987@vniz.net> References: <20120818195724.GA74684@vniz.net> <201208201409.55544.jhb@freebsd.org> <20120821010311.GA8250@vniz.net> <ygeharxdk97.wl%ume@mahoroba.org> <20120821044553.GA11375@vniz.net> <ygefw7gepmt.wl%ume@mahoroba.org> <20120821063027.GA41459@vniz.net> <ygeehn0enp7.wl%ume@mahoroba.org> <20120822000645.GA54651@vniz.net> <ygeipcblzf1.wl%ume@mahoroba.org> <20120823044137.GA7987@vniz.net>
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Hi,
>>>>> On Thu, 23 Aug 2012 08:41:37 +0400
>>>>> Andrey Chernov <ache@FreeBSD.ORG> said:
ache> On Thu, Aug 23, 2012 at 12:27:46AM +0900, Hajimu UMEMOTO wrote:
> A link-local address has a scope; an interface here. You cannot omit
> it on FreeBSD by default. To be able to omit it, specify something
> like ipv6_default_interface="em0" in your /etc/rc.conf.
ache> Please enlighten me a bit.
ache> RFC 4007 "11.6. Omitting Zone Indices" states:
ache> "The format defined in this document does not intend to invalidate the
ache> original format for non-global addresses; that is, the format without
ache> the zone index portion. As described in Section 6, in some common
ache> cases with the notion of the default zone index, there can be no
ache> ambiguity about scope zones. In such an environment, the
ache> implementation can omit the "%<zone_id>" part."
ache> Does absolutely trusted IPv6 local net using link-local addresses only
ache> falls in that case? If yes, is there a way to make address scope optional
ache> for all link-local addresses in FreeBSD?
FreeBSD doesn't have a feature to define a zone manually.
If a node has more than one interfaces, a link-local address without
zone identifer has ambiguity. If you mean `all link-local addresses'
are within one interface, yes, you can omit zone identifer by setting
ipv6_default_interface'
ache> Are link-local addresses ever usable for DNS or not due to their
ache> %<zone_id> part? F.e. for the case there is no global IPv6 net assigned at
ache> all but pure isolated IPv6 local network.
> In anyway, I don't recommend to use a link-local address for DNS.
ache> Is it only due to their scope part or other reasons exists too?
As you saw, dig(1) and host(1) doesn't work well with a link-local
address.
Not only a zone identifier, but also some implementation may handle a
link-local address (fe80:: prefix) as special.
Sincerely,
--
Hajimu UMEMOTO
ume@mahoroba.org ume@{,jp.}FreeBSD.org
http://www.mahoroba.org/~ume/
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