Re: Problem receiving UDP broadcast packets.

From	Grant Edwards <invalid@invalid.invalid>
Newsgroups	comp.lang.python
Subject	Re: Problem receiving UDP broadcast packets.
Date	2011-04-20 14:31 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<iomqod$e32$4@reader1.panix.com> (permalink)
References	(4 earlier) <mailman.592.1303257124.9059.python-list@python.org> <iol875$ah2$3@reader1.panix.com> <mailman.596.1303260785.9059.python-list@python.org> <iolc32$luj$1@reader1.panix.com> <mailman.604.1303269150.9059.python-list@python.org>

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On 2011-04-20, Dan Stromberg <drsalists@gmail.com> wrote:
> On Tue, Apr 19, 2011 at 6:15 PM, Grant Edwards <invalid@invalid.invalid> wrote:
>
>>> Or can you simply use a stupid netmask like /1 that picks up all the
>>> IP ranges? That way, the source-IP check wouldn't fail.
>>
>> That would require that the device somehow knows that it's not
>> configured correctly and should change the netmask to /1. ?The device
>> doesn't have any way to know that, and it must respond to the
>> discovery commands both before and after it's properly configured.
>
> - Actually, you Might be able to configure your device to have a
> netmask of 0.0.0.0, IP address of 255.255.255.255 and broadcast of
> 255.255.255.255.
> - I've seen something a bit similar used for detecting IP address
> conflicts automatically.
> - A network guru I used to work with told me that you could configure
> a machine with a broadcast of 255.255.255.255 more simply than messing
> around with the netmask, while still achieving the same result for
> general purpose networking.

I'll look into that.

>> I've reread the protocol documentation and noticed that the device has
>> to respond not only to broadcasts to 255.255.255.255 but also to
>> subnet broadcasts send to subnets it's not on. ?That pretty much
>> clinches the requirement to use a raw socket. :/
>
> With a netmask of 0.0.0.0, I suspect you will receive all broadcasts
> on the wire, given appropriate listening code.

That might be an option as well, as long as it doesn't disrupt normal
operation of the interface.

-- 
Grant Edwards               grant.b.edwards        Yow! Remember, in 2039,
                                  at               MOUSSE & PASTA will
                              gmail.com            be available ONLY by
                                                   prescription!!

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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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