Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds

Fernando Gont <fgont@si6networks.com> Thu, 31 October 2019 19:26 UTC

Return-Path: <fgont@si6networks.com>
X-Original-To: v6ops@ietfa.amsl.com
Delivered-To: v6ops@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C07AE120018 for <v6ops@ietfa.amsl.com>; Thu, 31 Oct 2019 12:26:28 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.899
X-Spam-Level:
X-Spam-Status: No, score=-1.899 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id cP8lFoRV-SkV for <v6ops@ietfa.amsl.com>; Thu, 31 Oct 2019 12:26:27 -0700 (PDT)
Received: from fgont.go6lab.si (fgont.go6lab.si [IPv6:2001:67c:27e4::14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id D0112120013 for <v6ops@ietf.org>; Thu, 31 Oct 2019 12:26:26 -0700 (PDT)
Received: from [192.168.1.36] (unknown [177.27.208.83]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by fgont.go6lab.si (Postfix) with ESMTPSA id CAD748698C; Thu, 31 Oct 2019 20:26:23 +0100 (CET)
To: Ted Lemon <mellon@fugue.com>, v6ops list <v6ops@ietf.org>
References: <CAO42Z2yQ_6PT3nQrXGD-mKO1bjsW6V3jZ_2kNGC2x586EMiNZg@mail.gmail.com> <B53CE471-C6E8-4DC1-8A72-C6E23154544F@fugue.com>
From: Fernando Gont <fgont@si6networks.com>
Openpgp: preference=signencrypt
Message-ID: <325e84aa-1703-e1ce-55a6-8790ceb7aff0@si6networks.com>
Date: Thu, 31 Oct 2019 16:21:04 -0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0
MIME-Version: 1.0
In-Reply-To: <B53CE471-C6E8-4DC1-8A72-C6E23154544F@fugue.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/v6ops/m-yZKG1GTSSW4O537YIcX6RC5S8>
Subject: Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds
X-BeenThere: v6ops@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: v6ops discussion list <v6ops.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/v6ops>, <mailto:v6ops-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/v6ops/>
List-Post: <mailto:v6ops@ietf.org>
List-Help: <mailto:v6ops-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/v6ops>, <mailto:v6ops-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 31 Oct 2019 19:26:29 -0000

Hello, Ted,


On 27/10/19 09:02, Ted Lemon wrote:
> Indeed, this would also not actually solve the problem.   At present,
> the ISPs are doing something that is out of spec and causes problems.
> If we “fix” this by accommodating what they do, does that help, or
> does it just encourage them to continue doing it?

Did happy eyeballs encourage broken IPv6 connectivity, or did it
actually help IPv6 deployment?




> What should be happening on the host with a prefix that’s deprecated
> is that TCP connections should be timing out.   This doesn’t take
> very long.  

~9 minutes, IIRC.


> And if there is a new prefix being advertised on the
> link, that address should have a valid lifetime newer than the old
> prefix, meaning that the next TCP connection should come from that
> new prefix, not the old one.

That's not correct. Neither the Valid Lifetime nor the Preferred
Lifetime affect address selection.




> I think Fernando’s plan to shorten some timers makes sense, but
> shortening the minimum really doesn’t—it just opens up an opportunity
> for an easy DoS, since I can now just send out death packets to the
> local network and break everything all at once.

The reality with ND attacks are (modulo sanity checks on the packets):
you enforce FHS, or you don't.




> If you Really Really want to be able to have the routers send out RAs
> that deprecate the default route, and, as Mark is saying here, to
> upgrade millions or perhaps billions of hosts, why not ask for
> something that’s a real improvement?

Every piece helps.



> First of all, fix CPEs so that they definitely support clean
> deprecation of prefixes using PD.

But robustness cannot rely on any of these specific bits.


>  Second, fix RA so that it’s
> non-repudiable by a device that doesn’t have the secret key.
> 
> SEND does this, sort of.  Nobody uses SEND because it tries to solve
> a too-big problem and does it using obsolete technology.   But the
> basic idea is good: include a public key in every RA that can be used
> to validate that the RA was signed with the corresponding private
> key.

What's the practical difference between that, an a network that supports
RA-Guard?



> When another RA arrives, see if it was signed with the same key.   If
> so, it came from the same router, and can be trusted to update
> whatever information that router sent, including flash-deprecating a
> prefix.   If not, ignore it.

In the non-SEND trust model, you do trust the local router. Why did you
trust the local router to configure your network, but not for
deprecating the prefix?

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492