netdev - Re: [PATCH net-next-2.6] ipv4: sysctl to block responding on down interface

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Date:	Thu, 1 Jul 2010 13:48:06 +0200
From:	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	Stephen Hemminger <shemminger@...tta.com>
Subject: Re: [PATCH net-next-2.6] ipv4: sysctl to block responding on down interface

Andi Kleen <andi@...stfloor.org> wrote on 2010/07/01 13:23:21:
>
> Joakim Tjernlund <joakim.tjernlund@...nsmode.se> writes:
>
> > Stephen Hemminger <shemminger@...tta.com> wrote on 2010/06/11 17:48:54:
> >>
> >> When Linux is used as a router, it is undesirable for the kernel to process
> >> incoming packets when the address assigned to the interface is down.
> >> The initial problem report was for a management application that used ICMP
> >> to check link availability.
> >>
> >> The default is disabled to maintain compatibility with previous behavior.
> >> This is not recommended for server systems because it makes fail over more
> >> difficult, and does not account for configurations where multiple interfaces
> >> have the same IP address.
> >>
> >> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
> >
> > Ping David et. all?
> > I too want this.
>
> Doesn't arpfilter enable this already? If you set in on the still up
> interfaces those will not answer to other IP addresses.
>
> This only works on the ARP level, so it has to wait until the arp
> cache in the remote host times out.

I tried that but it didn't work, but I didn't think of clearing
the ARP cache.
Anyhow, such methods seems worse than just doing ifconfig 0.0.0.0

  Jocke

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