Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751716Ab2HBUlJ (ORCPT ); Thu, 2 Aug 2012 16:41:09 -0400 Received: from oproxy8-pub.bluehost.com ([69.89.22.20]:47379 "HELO oproxy8-pub.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750949Ab2HBUlG (ORCPT ); Thu, 2 Aug 2012 16:41:06 -0400 Date: Thu, 2 Aug 2012 13:41:55 -0700 From: Jesse Barnes To: Dirk Gouders Cc: Rob Landley , Milton Miller , Borislav Petkov , Cong Wang , Jan Engelhardt , Linux Kernel Subject: Re: [RFC] netconsole.txt: "nc" needs "-p" to specify the listening port Message-ID: <20120802134155.791cfcce@jbarnes-desktop> In-Reply-To: References:

<501937F7.2070600@landley.net> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Identified-User: {10642:box514.bluehost.com:virtuous:virtuousgeek.org} {sentby:smtp auth 67.161.37.189 authed with jbarnes@virtuousgeek.org} Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7760 Lines: 203 On Thu, 02 Aug 2012 22:39:28 +0200 Dirk Gouders wrote: > Dirk Gouders writes: > > > Rob Landley writes: > > > >> On 07/29/2012 03:40 AM, Milton Miller wrote: > >>> [adding Rob as Doc maintanier] > >>> > >>> On Sat, 28 Jul 2012 about 11:08:16 -0000, Dirk Gouders wrote: > >>>> Borislav Petkov writes: > >>>> > >>>>> On Fri, Jul 27, 2012 at 11:24:53AM +0200, Dirk Gouders wrote: > >>>>>> Cong Wang writes: > >>>>>> > >>>>>>> On Fri, Jul 27, 2012 at 2:35 PM, Dirk Gouders > >>>>>>> wrote: > >>>>>>>> Hi Jesse, > >>>>>>>> > >>>>>>>> I would like to ask you to check if the documentation of "nc" in > >>>>>>>> netconsole.txt is still correct. I tried two different netcat packages > >>>>>>>> and both require "-p" to specify the listening port. I am wondering if > >>>>>>>> that changed after the use of "nc" has been documented. > >>>>>>> > >>>>>>> On Fedora 16, `nc -u -l ` works fine. > >>>>>> > >>>>>> Thanks for checking that. > >>>>>> > >>>>>> If the information I found is correct, Fedora uses OpenBSD's nc > >>>>>> codebase. The two netcat packages I tested on a Gentoo system differ in > >>>>>> requiring the -p switch for the port specification. > >>>>> > >>>>> So say exactly that in the doc: that the *BSD's version of nc doesn't > >>>>> need the port number specified with '-p' and you're covered. > >>>> OK, I tried that in the attached patch. > >>>> I'm not sure if every exeption needs to/should be documented, though. > >>>> > >>>> >From 3cdeac3e814471053129145c5fa8391acb365fd8 Mon Sep 17 00:00:00 2001 > >>>> From: Dirk Gouders > >>>> Date: Sat, 28 Jul 2012 12:32:49 +0200 > >>>> Subject: [PATCH] netconsole.txt: non-BSD versions of nc(1) require '-p' > >>>> switch > >>>> > >>>> Gentoo for example uses non-BSD versions of nc(1) which require > >>>> the '-p' switch to specify the listening port. > >>>> > >>>> --- > >>>> Documentation/networking/netconsole.txt | 3 ++- > >>>> 1 files changed, 2 insertions(+), 1 deletions(-) > >> > >> Did this ever resolve to a specific recommended patch? The one at the > >> start of the thread: > >> > >> http://lkml.indiana.edu/hypermail/linux/kernel/1207.3/01995.html > >> > >> Apparently isn't it...? > > > > Sorry for the delay. > > I tested the situation on a few distributions and am still thinking > > about a proper way to write it in a way without netconsole.txt becoming > > a kind of "netcat.txt". > > > > I would be glad about comments to what I currently have -- also, because > > I am not a native English speaker: > > > > ------------------------------------------------------------------------ > > The remote host can run syslogd or netcat to receive the kernel > > messages. On distributions using a BSD-based netcat version > > (e.g. Fedora, openSUSE and Ubuntu) the listening port must be > > specified without the -p switch: > > > > 'nc -u -l -p ' / 'nc -u -l ' or > > 'netcat -u -l -p ' / 'netcat -u -l ' > > ------------------------------------------------------------------------ > > > > At the end, I also attach what I have noted during the tests with the > > different distributions. > > > > Dirk > > > > ------------------------------------------------------------------------ > > Problem on systems where the gnu-netcat package provides a symbolic > > link /usr/bin/nc -> /usr/bin/netcat: > > > > gnu-netcat requires -p to specify the local port but does not complain > > if invoked as `nc -l -u '; you need to use -v to see that it > > does not do what you might expect: > > > > # nc -l -u 4444 -v > > Warning: Inverse name lookup failed for `0.0.17.92' > > ------------------------------------------------------------------------ > > > > Distro Package needs -p > > Command invocation > > ======================================================================== > > Arch gnu-netcat yes > > (Website nc | netcat > > documentation) > > openbsd-netcat no > > nc.openbsd > > ------------------------------------------------------------------------ > > Debian-6.0.5 netcat-openbsd no > > nc | netcat | nc.openbsd > > > > netcat / netcat-traditional (preinstalled) yes > > nc | netcat > > > > netcat6 yes > > nc | netcat | nc6 > > ------------------------------------------------------------------------ > > Fedora-17 nc (preinstalled) no > > nc > > > > nc6 > > nc6 yes > > ------------------------------------------------------------------------ > > Gentoo gnu-netcat yes > > netcat > > > > netcat yes > > nc > > > > netcat6 yes > > nc | nc6 > > ------------------------------------------------------------------------ > > OpenSUSE-12.1 netcat-openbsd no > > nc | netcat > > ------------------------------------------------------------------------ > > Ubuntu-12.04 netcat-openbsd (preinstalled) no > > Desktop nc | netcat | nc.openbsd > > > > netcat / netcat-traditional yes > > nc | netcat > > > > netcat6 yes > > nc | netcat | nc6 > > ------------------------------------------------------------------------ > > Here is a patch that also includes Jan's suggestion for socat(1). > > The problem with the patch is that the netcat part does not cover every > possible distribution/netcat-package situation but in my opinion it is a > bearable compromise with respect to keeping the example section compact. > > Dirk > > From d756d2750e4cf07d3c0942dc3c491d57631d4338 Mon Sep 17 00:00:00 2001 > From: Dirk Gouders > Date: Thu, 2 Aug 2012 22:20:16 +0200 > Subject: [PATCH] netconsole.txt: revision of examples for the receiver of kernel messages > > There are at least 4 implementations of netcat with the BSD-based > being the only one that has to be used without the -p switch to > specify the listening port. > > Jan Engelhardt suggested to add an example for socat(1). > --- > Documentation/networking/netconsole.txt | 19 +++++++++++++++++-- > 1 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt > index 8d02207..2e9e0ae2 100644 > --- a/Documentation/networking/netconsole.txt > +++ b/Documentation/networking/netconsole.txt > @@ -51,8 +51,23 @@ Built-in netconsole starts immediately after the TCP stack is > initialized and attempts to bring up the supplied dev at the supplied > address. > > -The remote host can run either 'netcat -u -l -p ', > -'nc -l -u ' or syslogd. > +The remote host has several options to receive the kernel messages, > +for example: > + > +1) syslogd > + > +2) netcat > + > + On distributions using a BSD-based netcat version (e.g. Fedora, > + openSUSE and Ubuntu) the listening port must be specified without > + the -p switch: > + > + 'nc -u -l -p ' / 'nc -u -l ' or > + 'netcat -u -l -p ' / 'netcat -u -l ' > + > +3) socat > + > + 'socat udp-recv: -' > > Dynamic reconfiguration: > ======================== Looks good to me, thanks Dirk. Reviewed-by: Jesse Barnes -- Jesse Barnes, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/