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Date: Tue, 4 Dec 2012 08:47:23 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Woody Wu <narkewoody@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Why a host not ping-able?
Message-ID: <20121204084723.4b992d49@pyramind.ukuu.org.uk>
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On Tue, 4 Dec 2012 06:17:25 +0000 (UTC)
Woody Wu <narkewoody@gmail.com> wrote:

> Hi, list
> 
> I am not sure this has something with kernel.  But the system I just
> generated cannot be reached from ping.  It can ping outside, but if I
> ping it from outside, I just get "Destination Host Unreachable".
> 
> I think there is not firewall in between, and the two host in the test
> are in the same ethernet sub network.  Is that possible the strange
> behavior caused by somehow misconfigured kernel?

Very unlikely. More likely you have a routing problem somewhere. tcpdump
or similar network monitoring tools are probably what you need.