IETF Logo Mail Archive

Re: [Ntp] Antw: Re: Antw: Re: New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)

Miroslav Lichvar <mlichvar@redhat.com> Wed, 29 May 2019 11:03 UTC

Return-Path: <mlichvar@redhat.com>
X-Original-To: ntp@ietfa.amsl.com
Delivered-To: ntp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A3616120106 for <ntp@ietfa.amsl.com>; Wed, 29 May 2019 04:03:34 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.901
X-Spam-Level:
X-Spam-Status: No, score=-6.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-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 aE_F0sgeIvVv for <ntp@ietfa.amsl.com>; Wed, 29 May 2019 04:03:33 -0700 (PDT)
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 21B8A12008D for <ntp@ietf.org>; Wed, 29 May 2019 04:03:33 -0700 (PDT)
Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 889B67E426; Wed, 29 May 2019 11:03:22 +0000 (UTC)
Received: from localhost (holly.tpb.lab.eng.brq.redhat.com [10.43.134.11]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D49D4611CD; Wed, 29 May 2019 11:03:19 +0000 (UTC)
Date: Wed, 29 May 2019 13:03:18 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Harlan Stenn <stenn@nwtime.org>
Cc: ntp@ietf.org
Message-ID: <20190529110318.GK11346@localhost>
References: <92e2c1f9-a745-c182-6194-c7ce819c8a3c@nwtime.org> <20190529101654.GI11346@localhost> <06d628cc-12b1-4a5d-1b17-5d5be5b95881@nwtime.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <06d628cc-12b1-4a5d-1b17-5d5be5b95881@nwtime.org>
User-Agent: Mutt/1.11.3 (2019-02-01)
X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 29 May 2019 11:03:27 +0000 (UTC)
Archived-At: <https://mailarchive.ietf.org/arch/msg/ntp/3h7mxxyzk6AcXNE50UY4Xn-4WW0>
Subject: Re: [Ntp] Antw: Re: Antw: Re: New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)
X-BeenThere: ntp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: <ntp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ntp>, <mailto:ntp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ntp/>
List-Post: <mailto:ntp@ietf.org>
List-Help: <mailto:ntp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ntp>, <mailto:ntp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 29 May 2019 11:03:35 -0000

On Wed, May 29, 2019 at 03:28:12AM -0700, Harlan Stenn wrote:
> If a client is both dumb about this and isn't using MAC protection, then
> how can the user claim they want to put any trust in the time on the
> target box?

There is a difference between off-path attacks and MITM attacks. I
think it's not unreasonable to expect the unauthenticated
client/server mode (unlike the symmetric mode) to be resilient against
off-path attacks.

> Even if I'm wrong by as much as you claim, anybody who cares can easily:
> 
> - report the incoming bogus transmit timestamp packets
> - report the incoming bogus MAC packets

That opens a possibility for a DoS attack on the logging mechanism or
the admin/user.

-- 
Miroslav Lichvar

v2.23.0 | Report a Bug | By Email