From owner-freebsd-net@freebsd.org  Wed Aug 17 11:18:11 2016
Return-Path: <owner-freebsd-net@freebsd.org>
Delivered-To: freebsd-net@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8D7A5BBBAE2
 for <freebsd-net@mailman.ysv.freebsd.org>;
 Wed, 17 Aug 2016 11:18:11 +0000 (UTC) (envelope-from kp@FreeBSD.org)
Received: from venus.codepro.be (venus.codepro.be [IPv6:2a01:4f8:162:1127::2])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256
 bits))
 (Client CN "*.codepro.be", Issuer "Gandi Standard SSL CA 2" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 5BC061A3D
 for <freebsd-net@freebsd.org>; Wed, 17 Aug 2016 11:18:11 +0000 (UTC)
 (envelope-from kp@FreeBSD.org)
Received: from [192.168.228.1] (global-5-13.nat-1.net.cam.ac.uk [131.111.5.13])
 (Authenticated sender: kp)
 by venus.codepro.be (Postfix) with ESMTPSA id DFD5D1F152;
 Wed, 17 Aug 2016 13:18:08 +0200 (CEST)
From: "Kristof Provost" <kp@FreeBSD.org>
To: mail+lists@m.jwh.me.uk
Cc: freebsd-net@freebsd.org
Subject: Re: PF weirdness
Date: Wed, 17 Aug 2016 12:18:07 +0100
Message-ID: <C1AF5889-E4D7-400B-AA67-25D7990EC5F4@FreeBSD.org>
In-Reply-To: <028b01d1f871$7b9af200$72d0d600$@m.jwh.me.uk>
References: <028b01d1f871$7b9af200$72d0d600$@m.jwh.me.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
X-Mailer: MailMate (2.0BETAr6048)
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 17 Aug 2016 11:18:11 -0000

On 17 Aug 2016, at 11:24, mail+lists@m.jwh.me.uk wrote:
> Ok so, I have an ERL that just does PPPoE and NAT via PF, however it 
> seems
> to be modifying the packets passing through the nat filter such that
> traceroutes end up like this:
>
> C:\Users\jwh>tracert -d -w 1 8.8.8.8
>
> Tracing route to 8.8.8.8 over a maximum of 30 hops
>
>   1     5 ms     1 ms     1 ms  172.21.88.254
>   2    47 ms    40 ms    39 ms  8.8.8.8
>   3    40 ms     *       39 ms  8.8.8.8
>   4    37 ms    25 ms    67 ms  8.8.8.8

That’s PR 201519.
I’m looking into it, but right now I have no idea why it happens.
It seems to be fine on head (and likely also on 11), and I don’t see 
any obvious differences in pf that could cause this.

Regards,
Kristof