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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org, davem@davemloft.org
Subject: Re: [PATCH] net/icmp: restore source address if packet is NATed
Date: Thu, 9 Nov 2017 09:35:16 +0900	[thread overview]
Message-ID: <CAHmME9oYGQpr7+aq7ByQ4UVYMY5aFky09NrHpVRYNMZ+XiDVDw@mail.gmail.com> (raw)
In-Reply-To: <20171109000134.GC5512@breakpoint.cc>

On Thu, Nov 9, 2017 at 9:01 AM, Florian Westphal <fw@strlen.de> wrote:
> I think correct solution is to never allow drivers to do something like
> this.  What is the use case here? Normal IP stack should send
> imcp/pkttobig errors, and that will work fine since it occurs pre-snat.

The use case is particular tunneling devices -- virtual interfaces.
It's possible that a tunnel device won't be able to transmit a packet,
due to some particular state issue -- no encryption key available,
incomplete configuration for a particular destination, etc -- and in
that case, it's quite important to be able to send an error --
ICMP_DEST_UNREACH,ICMP_HOST_UNREACH -- back to the sender, rather than
letting packets disappear into a blackhole without any useful
notification.

  reply	other threads:[~2017-11-09  0:35 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-08 14:08 [PATCH] net/icmp: restore source address if packet is NATed Jason A. Donenfeld
2017-11-09  0:01 ` Florian Westphal
2017-11-09  0:35   ` Jason A. Donenfeld [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-06-24  2:17 Jason A. Donenfeld
2017-06-25 15:49 ` David Miller
2017-06-25 22:52   ` Jason A. Donenfeld
2017-06-26  1:48     ` David Miller

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