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From: Rob Landley <rob@landley.net>
To: Woody Wu <narkewoody@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Why a host not ping-able?
Date: Tue, 04 Dec 2012 05:34:54 -0600	[thread overview]
Message-ID: <1354620894.27682.5@driftwood> (raw)
In-Reply-To: <slrnkbr59r.us1.narkewoody@zuhnb712.local.com> (from narkewoody@gmail.com on Tue Dec  4 00:17:25 2012)

On 12/04/2012 12:17:25 AM, Woody Wu wrote:
> Hi, list
> 
> I am not sure this has something with kernel.

It doesn't.

> 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".

Some distributions' default firewall rules respond to icmp packets with  
a host unreachable packet. This is a system/network administration  
thing (iptables) and nothing to do with kernel development.

> I think there is not firewall in between,

There's a firewall  built into linux, read the man page for the  
"iptables" command. The "iptables-save" command dumps your entire  
current ruleset to stdout so you can see what's in there. (You might  
have to run it as root, I forget.)

https://help.ubuntu.com/community/IptablesHowTo

Rob

  parent reply	other threads:[~2012-12-04 11:34 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-04  6:17 Woody Wu
2012-12-04  8:47 ` Alan Cox
2012-12-04 11:34 ` Rob Landley [this message]
2012-12-05  3:24   ` Woody Wu

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