IETF Logo Mail Archive

Re: [Ntp] Antwort: Re: The trick to timestamp with authentication

Dieter Sibold <dsibold.ietf@gmail.com> Mon, 07 December 2020 14:52 UTC

Return-Path: <dsibold.ietf@gmail.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 310B53A13ED for <ntp@ietfa.amsl.com>; Mon, 7 Dec 2020 06:52:19 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Level:
X-Spam-Status: No, score=-2.098 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
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 oagzfHQ6Z6tE for <ntp@ietfa.amsl.com>; Mon, 7 Dec 2020 06:52:17 -0800 (PST)
Received: from mail-wr1-x434.google.com (mail-wr1-x434.google.com [IPv6:2a00:1450:4864:20::434]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 7CC213A0E02 for <ntp@ietf.org>; Mon, 7 Dec 2020 06:52:17 -0800 (PST)
Received: by mail-wr1-x434.google.com with SMTP id a12so6233001wrv.8 for <ntp@ietf.org>; Mon, 07 Dec 2020 06:52:17 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version; bh=Fp/pxjezbTgPzUMy16PETHEZKJjXxf1toEes2QdeW+0=; b=PEigS9wdM7f775KzWKxD1TcWM8GhVuueMpuEoZ5qHD+wgTw/yx58qoaCxBeMIIZic/ 5juSpNwHRhRSmMF593/A9P4Bt2R+zqI/YFXuF4v84qTQiG8R0EDWGgTQGk2tsicbbmAl 0fyFAbSlmJPIygT+TDcmu4SlllMZ4gIqPBH/Lgi/PYkTAXChWSjJw1zHvOyZkDvWYstw nViAxc+d/kS+QI2guMTB+ciph88VSI9uYegjuwgGAf/n+X9kJf/5aM7zqrE7VPC5H2Zc 4P3ndjxd5Htwyi0aKNhCqC609FH7Da2EdBxDKFKRjfvVgQ4sJeUD1Bqh6XwuZ+b7DcwD h3Xg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version; bh=Fp/pxjezbTgPzUMy16PETHEZKJjXxf1toEes2QdeW+0=; b=NFb27eVaiR8GhFMfs4yoECVeKsLGK2GHmjRRZdWpyKV116tHR6kU0ZE8Ki4UEc9lY5 j8+Su0iajjTTM09UpPFlk1+aAIesOpEq2WWHFz7JwvrEzeS9AQzWaRx1TUg7ZHVm8beB iRvydO7gKhKJimBdA/6IGEzqfCgKK3lfeNRTOuFm41bgkop8urtcP9Da9oKl1LFP3JRp Z/6y8LsisTfpzZN8WScuHjmNUDOmKQ6Kn9k6y/mRdotfolAzsePbpJ2qYCs9zNnnIwOk o64TK8xcpWOp2l/v5UPyirwF0Gspdu5fkBBUb+t8cO06nDV7Synpqj0ohCwJWMS72UUs /BMA==
X-Gm-Message-State: AOAM533e+YBx3dML+WdfP4JKsRHQMsCqJ/VsZXFq5jiDRD8hDh/vJoKN mIHQenfX5Aw3guvzgoeIIME=
X-Google-Smtp-Source: ABdhPJzNz0xYmr5y6g9Vj24K49ROmXen9f85XYJJKsFbGckEy2/Pd//++VUl80xOw02CFM4Lix1jaQ==
X-Received: by 2002:a5d:4242:: with SMTP id s2mr11522173wrr.187.1607352735831; Mon, 07 Dec 2020 06:52:15 -0800 (PST)
Received: from [192.168.111.41] (p200300d17f0e670020d260b825d30818.dip0.t-ipconnect.de. [2003:d1:7f0e:6700:20d2:60b8:25d3:818]) by smtp.gmail.com with ESMTPSA id j7sm14639793wmb.40.2020.12.07.06.52.14 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Dec 2020 06:52:14 -0800 (PST)
From: Dieter Sibold <dsibold.ietf@gmail.com>
To: Miroslav Lichvar <mlichvar@redhat.com>
Cc: kristof.teichel@ptb.de, ntp@ietf.org
Date: Mon, 07 Dec 2020 15:52:13 +0100
X-Mailer: MailMate (1.13.2r5673)
Message-ID: <D00475BE-A5F5-4AC2-96A8-75D94F678FCE@gmail.com>
In-Reply-To: <20201207135001.GJ2352378@localhost>
References: <20201207105406.GF2352378@localhost> <doug.arnold@meinberg-usa.com> <BEF7C4D9-81CD-42AD-BA06-433D45C0DCD1@meinberg-usa.com> <20201203233634.15F7940605C@ip-64-139-1-69.sjc.megapath.net> <12C6B0FF-8C20-4363-AF41-FDF98B2D8072@meinberg-usa.com> <OF24F50CB5.1E226959-ONC1258637.0049B781-C1258637.0049B784@ptb.de> <20201207135001.GJ2352378@localhost>
MIME-Version: 1.0
Content-Type: text/plain; format="flowed"
Archived-At: <https://mailarchive.ietf.org/arch/msg/ntp/oFHr6VTwg1LI1a7i2gpnw_H2OgA>
Subject: Re: [Ntp] Antwort: Re: The trick to timestamp with authentication
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: Mon, 07 Dec 2020 14:52:19 -0000

But delaying may be easier to monitor since it increases the round trip 
delay, which is not the case if an correction field contains a forged 
timestamp.

Dieter




On 7 Dec 2020, at 14:50, Miroslav Lichvar wrote:

> On Mon, Dec 07, 2020 at 02:25:11PM +0100, kristof.teichel@ptb.de 
> wrote:
>>    But having unauthenticated corrections just makes it easier for 
>> the
>>    attacker, because writing a false correction might be less effort 
>> than an
>>    actual delay attack.
>
> I'd say it is the opposite. Delaying a packet is not that difficult.
> For example, you can generate traffic in order to increase queueing
> delays in switches/routers.
>
> In a MITM attack you need to prevent the original packet sent by the
> client or server reaching the other host. If you can do that, is it
> easier to sent a modified packet than just waiting a bit before
> sending the captured packet unmodified? I don't think there is a big
> difference.
>
> -- 
> Miroslav Lichvar
>

> _______________________________________________
> ntp mailing list
> ntp@ietf.org
> https://www.ietf.org/mailman/listinfo/ntp

v2.23.0 | Report a Bug | By Email