netdev - Re: [PATCH net-next v2] ipv6: sysctl to restrict candidate source addresses

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Date:	Wed, 8 Jul 2015 10:29:20 +0900
From:	Lorenzo Colitti <lorenzo@...gle.com>
To:	Erik Kline <ek@...gle.com>
Cc:	吉藤英明 <hideaki.yoshifuji@...aclelinux.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCH net-next v2] ipv6: sysctl to restrict candidate source addresses

On Mon, Jul 6, 2015 at 12:05 PM, Erik Kline <ek@...gle.com> wrote:
> Per RFC 6724, section 4, "Candidate Source Addresses":
>
>     It is RECOMMENDED that the candidate source addresses be the set
>     of unicast addresses assigned to the interface that will be used
>     to send to the destination (the "outgoing" interface).
>
> Add a sysctl to enable this behaviour.
>
> Signed-off-by: Erik Kline <ek@...gle.com>

I think this is useful, because it ensures that devices with a working
IPv6 configuration on interface A, and a partial IPv6 configuration on
interface B do not attempt to send packets on interface B using
interface A's source address.

Example: there are home routers in the wild that send out an IPv6
router advertisement that configures a default route but no IPv6
address. This change makes it so that the host does not attempt to use
an IPv6 address from another network (e.g., a cellular data
connection) on the home network.

It is also what the RFC recommends.

Acked-by: Lorenzo Colitti <lorenzo@...gle.com>
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