From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>,
Netfilter Development <netfilter-devel@vger.kernel.org>
Subject: Re: Documentation question
Date: Mon, 5 Jul 2021 10:56:10 +0200 [thread overview]
Message-ID: <20210705085610.GB16975@salvia> (raw)
In-Reply-To: <YOJINLIUz9fFAxa2@slk1.local.net>
On Mon, Jul 05, 2021 at 09:45:56AM +1000, Duncan Roe wrote:
> Hi Pablo,
>
> Did you follow the email thread
> https://www.spinics.net/lists/netfilter/msg60278.html?
>
> In summary, OP asked:
> > Good morning! I am using the nf-queue.c example from
> > libnetfilter_queue repo. In the queue_cb() function, I am trying to
> > get the conntrack info but this condition is always false.
> >
> > if(attr[NFQA_CT])
> >
> > I can see the flow in conntrack -L output. Anyone know what I am
> > missing? Appreciate your help!
>
> and Florian replied:
> > IIRC you need to set NFQA_CFG_F_CONNTRACK in NFQA_CFG_FLAGS when setting
> > up the queue. The example only sets F_GSO, so no conntrack info is
> > added.
>
> My question is, where should all this have been documented?
>
> `man nfq_set_queue_flags` documents NFQA_CFG_F_CONNTRACK, but
> nfq_set_queue_flags() is deprecated and OP was not using it.
>
> The modern approach is to code
> > mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(NFQA_CFG_F_GSO));
>
> NFQA_CFG_MASK is supplied by a libnetfilter_queue header, while
> mnl_attr_put_u32() is a libmnl function. What to do?
NFQA_CFG_MASK is supplied by linux/netfilter/nfnetlink_queue.h
The UAPI header is the main reference, it provides the kernel
definitions for the netlink attributes.
libnetfilter_queue provides a "cache copy" of this header too, that
is: libnetfilter_queue/linux_nfnetlink_queue.h
next prev parent reply other threads:[~2021-07-05 8:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-04 23:45 Documentation question Duncan Roe
2021-07-05 8:56 ` Pablo Neira Ayuso [this message]
2021-07-05 13:13 ` Duncan Roe
2021-07-05 14:42 ` Pablo Neira Ayuso
2021-07-06 4:27 ` [PATCH libnetfilter_queue] src: examples: Use libnetfilter_queue cached linux headers throughout Duncan Roe
2021-07-06 5:36 ` [PATCH libnetfilter_queue v2] " Duncan Roe
2021-07-06 22:52 ` Pablo Neira Ayuso
2021-07-07 1:58 ` Duncan Roe
2021-07-18 5:27 ` Duncan Roe
-- strict thread matches above, loose matches on Subject: below --
2019-12-15 2:02 Documentation question Duncan Roe
2019-12-20 0:29 ` Pablo Neira Ayuso
2019-12-21 10:43 ` Duncan Roe
2019-12-22 2:23 ` Duncan Roe
2019-11-20 23:09 Duncan Roe
2019-11-20 23:26 ` Florian Westphal
2019-11-21 5:33 ` Duncan Roe
2019-10-30 9:07 Duncan Roe
2019-10-30 9:15 ` Pablo Neira Ayuso
2019-10-30 9:38 ` Duncan Roe
2019-10-30 9:47 ` Pablo Neira Ayuso
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