From: Florian Westphal <fw@strlen.de>
To: Daniel Collins <daniel.collins@smoothwall.net>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: Packet loss when using NFQUEUE and nf_conntrack_ipv4
Date: Fri, 19 Jul 2013 11:25:47 +0200 [thread overview]
Message-ID: <20130719092547.GF22686@breakpoint.cc> (raw)
In-Reply-To: <CAOmdcgVVgPxB2BV0qxoXVquPVt-21+JvYq0ywFu7=RiJ4i7JXQ@mail.gmail.com>
Daniel Collins <daniel.collins@smoothwall.net> wrote:
> NF_ACCEPT'd using nfq_set_verdict and forwarded on by the kernel, as
> expected. Any packets transmitted within a small window (microseconds,
> depending on hardware) after the first packet, are received by the
> userspace program, the call to nfq_set_verdict suceeds but the kernel
> doesn't forward the packet on. Any packets transmitted after this
> window are received and forwarded correctly.
>
> Is this a known issue?
Yes. The packets are tossed because the conntrack they're associated
with is unconfirmed, and on reinject they clash with the unconfirmed
ct of the 1st packet that has been inserted into the conntrack table.
The packets that arrive after the first packet has left the box
go through because the conntrack lookup finds an existing
entry.
next prev parent reply other threads:[~2013-07-19 9:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-19 8:57 Packet loss when using NFQUEUE and nf_conntrack_ipv4 Daniel Collins
2013-07-19 9:25 ` Florian Westphal [this message]
2013-07-22 8:33 ` Daniel Collins
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