From: Florian Westphal <fw@strlen.de>
To: Korodev <korodev@gmail.com>
Cc: Florian Westphal <fw@strlen.de>, netfilter@vger.kernel.org
Subject: Re: Timestamps, NFLOG, and ULOG
Date: Fri, 22 May 2020 02:21:34 +0200 [thread overview]
Message-ID: <20200522002134.GB26949@breakpoint.cc> (raw)
In-Reply-To: <CAKOsuLopu0VZna9YTK7u-bri7RjodX6ufrqz_n4tLGXHOLNw7w@mail.gmail.com>
Korodev <korodev@gmail.com> wrote:
> On Thu, May 21, 2020 at 6:26 PM Florian Westphal <fw@strlen.de> wrote:
> > Its expected. If you want rx timestamps you should set
> > SO_TIMESTAMP(NS) socket option,
>
> Thank you for your reply. My understanding is that SO_TIMESTAMP is a
> socket option I could set for an application that I control, but how
> would I go about enabling that such that IPTables, Netlink, and ULOGd
> are aware?
Setting this option makes the kernel record a timestamp at reception
time for all packets it receives (it won't know the socket the packet
will be delivered to yet, so it can't do this in a fine-grained way).
This is off by default for performance reasons.
Ideally ulogd should have an option to enable this (it doesn't have
one).
> I assumed I would at least get the software timestamp at
> which the kernel received the packet.
No, the kernel does not record a timestamp by default.
prev parent reply other threads:[~2020-05-22 0:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 18:44 Timestamps, NFLOG, and ULOG Korodev
2020-05-21 23:26 ` Florian Westphal
2020-05-21 23:58 ` Korodev
2020-05-22 0:21 ` Florian Westphal [this message]
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