Re: Problem receiving UDP broadcast packets.

From	Grant Edwards <invalid@invalid.invalid>
Newsgroups	comp.lang.python
Subject	Re: Problem receiving UDP broadcast packets.
Date	2011-04-21 14:22 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<iopei9$sin$1@reader1.panix.com> (permalink)
References	(7 earlier) <iolc32$luj$1@reader1.panix.com> <BANLkTiniO=gXK=s5gXN5Y7SoR7=uWntUPg@mail.gmail.com> <mailman.605.1303269379.9059.python-list@python.org> <iomq63$e32$1@reader1.panix.com> <mailman.675.1303349764.9059.python-list@python.org>

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On 2011-04-21, Dan Stromberg <drsalists@gmail.com> wrote:
> On Wed, Apr 20, 2011 at 7:21 AM, Grant Edwards <invalid@invalid.invalid> wrote:
>> On 2011-04-20, Dan Stromberg <drsalists@gmail.com> wrote:
>>> On Tue, Apr 19, 2011 at 8:12 PM, Dan Stromberg <drsalists@gmail.com> wrote:
>>>> I agree though that you're kind of pushing IP in a direction it wasn't
>>>> intended to go.
>>>
>>> It just occurred to me: You might get some additional mileage out of
>>> popping the network adapter into promiscuous mode. ?In fact, it Might
>>> be necessary irrespective of the rest of your approach.
>>
>> The network adapter is already receiving all the packets I want to
>> receive, so putting it into promiscuous mode would only increase the
>> number of unwanted packets.
>
> I think tcpdump and tshark (was tethereal) will put the interface into
> promiscuous mode so it can see more traffic;

It can (and by default does).  I was using "-p" so it didn't.

> on OSF/1 (Tru64), we had
> to do this manually for said programs to see all that was possible
> (barring the presence of a switch not repeating packets the way
> routers and hubs would).

 * The packets were being sent to MAC address ff:ff:ff:ff:ff:ff, so the
   NIC does not have to be in promiscuous mode to receive them.

 * tcpdump saw them even when it doesn't put the NIC in promiscuous
   mode.

 * The kernel was seeing the packets because it was logging them as
   martians and discarding them (something I didn't notice until later).

 * Turning off reverse-path filtering in the TCP stack allowed the
   packets to be received as expected.

-- 
Grant Edwards               grant.b.edwards        Yow! I was making donuts
                                  at               and now I'm on a bus!
                              gmail.com

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Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-19 22:21 +0000
  Re: Problem receiving UDP broadcast packets. Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2011-04-20 01:13 +0200
    Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-19 23:21 +0000
      Re: Problem receiving UDP broadcast packets. Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2011-04-20 01:40 +0200
        Re: Problem receiving UDP broadcast packets. Dan Stromberg <drsalists@gmail.com> - 2011-04-19 16:52 -0700
          Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 00:09 +0000
            Re: Problem receiving UDP broadcast packets. Chris Angelico <rosuav@gmail.com> - 2011-04-20 10:53 +1000
              Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 01:15 +0000
                Re: Problem receiving UDP broadcast packets. Chris Angelico <rosuav@gmail.com> - 2011-04-20 11:24 +1000
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 03:05 +0000
                Re: Problem receiving UDP broadcast packets. Dan Stromberg <drsalists@gmail.com> - 2011-04-19 20:12 -0700
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 14:31 +0000
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 15:42 +0000
                Re: Problem receiving UDP broadcast packets. Dan Stromberg <drsalists@gmail.com> - 2011-04-19 20:16 -0700
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 14:21 +0000
                Re: Problem receiving UDP broadcast packets. Dan Stromberg <drsalists@gmail.com> - 2011-04-20 18:35 -0700
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-21 14:22 +0000
                Re: Problem receiving UDP broadcast packets. Heiko Wundram <modelnine@modelnine.org> - 2011-04-21 08:22 +0200
            Re: Problem receiving UDP broadcast packets. Roy Smith <roy@panix.com> - 2011-04-19 23:35 -0400
              Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 14:23 +0000
            Re: Problem receiving UDP broadcast packets. Sherm Pendley <sherm.pendley@gmail.com> - 2011-04-20 06:07 -0400
              Re: Problem receiving UDP broadcast packets. Adam Tauno Williams <awilliam@whitemice.org> - 2011-04-20 06:20 -0400
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 15:37 +0000
        Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-19 23:54 +0000
          Re: Problem receiving UDP broadcast packets. Heiko Wundram <modelnine@modelnine.org> - 2011-04-20 08:45 +0200
            Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 14:30 +0000
              Re: Problem receiving UDP broadcast packets. Heiko Wundram <modelnine@modelnine.org> - 2011-04-20 16:53 +0200
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 15:24 +0000
                Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 15:32 +0000
              Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 15:50 +0000
  Re: Problem receiving UDP broadcast packets. Dan Stromberg <drsalists@gmail.com> - 2011-04-19 16:40 -0700
    Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 00:00 +0000
      Re: Problem receiving UDP broadcast packets. Chris Angelico <rosuav@gmail.com> - 2011-04-20 10:32 +1000
  Re: Problem receiving UDP broadcast packets. Thomas Heller <theller@ctypes.org> - 2011-04-20 12:18 +0200
    Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 14:35 +0000
  Re: Problem receiving UDP broadcast packets. Grant Edwards <invalid@invalid.invalid> - 2011-04-20 22:25 +0000

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