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Date:      Mon, 14 Dec 2015 22:17:50 +0100
From:      Kristof Provost <kp@FreeBSD.org>
To:        murdoch.john@moumantai.de
Cc:        "freebsd-pf@freebsd.org" <freebsd-pf@freebsd.org>
Subject:   Re: Unable to upload to S3 when pf is activated
Message-ID:  <28626F70-AF5A-4417-BEF2-2DC759EC948E@FreeBSD.org>
In-Reply-To: <97FFE650-FFC8-4EB3-81EF-CF3B7A55B1F1@moumantai.de>
References:  <DFB96E94-2255-4CA2-B1B1-EA0B3230122C@moumantai.de> <8F94731D-E0B3-4B94-83B8-1928ECBC20B8@FreeBSD.org> <97FFE650-FFC8-4EB3-81EF-CF3B7A55B1F1@moumantai.de>

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> On 14 Dec 2015, at 21:38, murdoch.john@moumantai.de wrote:
> yes, the machine runs on Amazon and yes again -tso fixed the problem.
>=20
> Could I have seen this somehow watching the pf log? Maybe package =
length?

It=E2=80=99d be hard to spot. The problem was related to the checksums, =
so you=E2=80=99d have to explicitly look for checksum errors.
To make it worse, you=E2=80=99d not spot the problem looking at tcpdump =
captures on the machine itself (because you=E2=80=99d see the =
pre-segmentation packets).

In effect, the best, if not only, way to spot it would be to set up a =
TCP connection to another machine you control and then send large chunks =
of data (to trigger TSO) and look at those checksums.

Regards,
Kristof=



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