netdev - Re: [PATCH net-next v4] IPv6: use anycast addresses as source addresses in echo reply

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Message-ID: <20140107130938.GE24730@order.stressinduktion.org>
Date:	Tue, 7 Jan 2014 14:09:38 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	François-Xavier Le Bail <fx.lebail@...oo.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki Yoshifuji <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH net-next v4] IPv6: use anycast addresses as source addresses in echo reply

On Tue, Jan 07, 2014 at 04:38:38AM -0800, François-Xavier Le Bail wrote:
> On Mon, 1/6/14, Hannes Frederic Sowa <hannes@...essinduktion.org> wrote:
> 
> >>But if an echo request arrive on an interface
> >> which do not listen at this LL anycast, is a reply can occur ?
>  
> > I thought quite the opposite with anycast + forwarding
> > enabled, that  we would process the packet.
> 
> yes, for a global scope anycast.
> But a routers must not forward any packets with link-local source or destination addresses to other links, thus also ll anycast.

Of course, but in this case I hesitated because I haven't dealt a lot
with anycast recently in routing code and it seemed like RTF_ANYCAST is
exclusive-or with RTF_LOCAL. So I was really unsure if this protection
was really in place. We already had some illegal forwarding/input paths
in the past. ;)

Greetings,

  Hannes

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