Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #3715

Re: Problem receiving UDP broadcast packets.

Path csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path <modelnine@modelnine.org>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.008
X-Spam-Evidence '*H*': 0.98; '*S*': 0.00; '(i.e.,': 0.03; 'socket': 0.05; 'option,': 0.07; 'python': 0.07; '"""': 0.09; '(there': 0.09; 'subject:Problem': 0.09; '"from': 0.16; 'addr': 0.16; 'capturing': 0.16; 'header)': 0.16; 'nodes': 0.16; 'received:10.2': 0.16; 'sock': 0.16; 'case.': 0.16; 'header:In- Reply-To:1': 0.22; 'specified': 0.22; '(and': 0.22; '(without': 0.23; 'instead': 0.26; 'looks': 0.28; 'load': 0.28; 'supports': 0.29; 'mode': 0.29; 'interface.': 0.29; '---': 0.31; 'mirror': 0.31; 'transport': 0.31; 'types.': 0.31; 'data,': 0.31; 'to:addr :python-list': 0.32; "i've": 0.33; 'relatively': 0.33; 'using': 0.34; 'actually': 0.34; 'print': 0.35; 'header:User-Agent:1': 0.35; 'like:': 0.35; 'rather': 0.36; '(with': 0.36; 'raw': 0.37; 'either': 0.37; 'but': 0.38; 'received:org': 0.38; 'skip:s 30': 0.39; 'to:addr:python.org': 0.39; 'add': 0.39; 'similar': 0.40; 'would': 0.40; 'contacting': 0.66; 'broadcast': 0.68; 'address),': 0.84; 'client-side': 0.84; 'listens': 0.84; 'schrieb': 0.84; 'similar.': 0.84; 'sniffer': 0.84
DKIM-Signature v=1; a=rsa-sha256; c=simple/simple; d=modelnine.org; s=modelnine1012; t=1303311236; bh=g7s68ICw+71Fq48cBAVriso/D3jcB5OTEWff1ALeFg8=; h=Message-ID:Date:From:MIME-Version:To:Subject:References: In-Reply-To:Content-Type:Content-Transfer-Encoding; b=LO8roq9RMqB069glF69Ow6X2INzW2JGREx80lPX4JBxuLxAEYJp8mFsNCAwi1R+IN jXrmJoDAsAQQVRuPMdjcyy5g3UHtmqPgh5hDZGDncqWp0o9tgK34KLFBoLJRM8fVTe TEGA1Igu97MxzDPkb2IELPSf+qNiUQut/bEqMFu4=
Date Wed, 20 Apr 2011 16:53:53 +0200
From Heiko Wundram <modelnine@modelnine.org>
User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9
MIME-Version 1.0
To python-list@python.org
Subject Re: Problem receiving UDP broadcast packets.
References <iol1tv$8dn$1@reader1.panix.com> <4dae172e$0$65870$e4fe514c@news.xs4all.nl> <iol5dm$rdb$2@reader1.panix.com> <4dae1d82$0$81483$e4fe514c@news.xs4all.nl> <iol7bu$ah2$1@reader1.panix.com> <mailman.620.1303282060.9059.python-list@python.org> <iomqll$e32$3@reader1.panix.com>
In-Reply-To <iomqll$e32$3@reader1.panix.com>
X-Enigmail-Version 1.1.1
Content-Type text/plain; charset=ISO-8859-1
Content-Transfer-Encoding 7bit
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.12
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.649.1303311238.9059.python-list@python.org> (permalink)
Lines 41
NNTP-Posting-Host 82.94.164.166
X-Trace 1303311238 news.xs4all.nl 34849 [::ffff:82.94.164.166]:40494
X-Complaints-To abuse@xs4all.nl
Xref x330-a1.tempe.blueboxinc.net comp.lang.python:3715

Show key headers only | View raw

Am 20.04.2011 16:30, schrieb Grant Edwards:
>> If you need to see the packets regardless, either use a promiscuous mode
>> sniffer (i.e., tcpdump, but that's relatively easy to mirror in Python
>> using SOCK_RAW, capturing packets at the ethernet level), or add a route
>> on your system for the 192.168.x.x network on the same interface.
> 
> I've thought about the SOCK_RAW option, but the CPU load of looking
> all received Ethernet packets in user-space would be a big down-side.

Not necessarily: instead of using UDP datagrams to send the data, use
ethernet datagrams (without any IP/UDP header) with your own
ethernet-type (there is a range of "local" types that you can use for
your own local use-case), and then simply create a RAW socket that only
listens on packets that have the specified ethernet types. We use
something similar at work for a high-availability application.

The server-side looks something like:

"""
PKT_TYPE = 0x1234 # My very own ethertype.

sock = socket(AF_PACKET,SOCK_DGRAM,htons(PKT_TYPE))
sock.bind(("ethxyz",PKT_TYPE))

while True:
    data, (_, _, _, _, addr) = sock.recvfrom(1500)
    print "I got:", repr(data), "from etheraddr:", addr
"""

The client-side looks similar.

Because you're using UDP broacast, you have unreliable transport anyway,
and if the client-side supports sending ethernet datagrams (with a
broadcast address), I'd rather advise to use that for your use case.
This makes you independent of IP configuration (and as I can see, you're
actually not interested in the "routing" that IP gives you, but rather
interested in contacting all nodes on a local ethernet; why not use
ethernet directly?).

-- 
--- Heiko.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

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

csiph-web