Re: Multicast listening
Re: Multicast listening
- Subject: Re: Multicast listening
- From: "Hamish Allan" <email@hidden>
- Date: Thu, 10 Jan 2008 11:44:58 +0000
How are you generating the packets from the external source? Using the
same netcat command?
It sounds as though your external source is generating multicast
packets with a TTL of 0.
Hamish
On Jan 10, 2008 11:04 AM, Alex Tarter <email@hidden> wrote:
>
> Thanks for your suggestion, when I ran the code from Hamish (or indeed
> my original code) it didn't work when packets were sent to it from an
> external source.
>
> They both did work when I used my own computer to generate the source
> (ie typing "nc -u 239.192.12.0 48640").
>
> Again both sets of code worked fine with an external source when
> Wireshark was turned on! I've tried changing the subnet address of my
> computer but that didn't work. There's something screwy going on here.
>
> I've tried running both pieces of software on other computers but to no
> avail. I've shut down my computer and restarted and run the software
> without ever loading Wireshark but it didn't work.
>
> I'm running 10.4.11 on one computer and 10.3.9 on the other, so I don't
> think it's an OS update problem.
>
> When I run the software and run Wireshark on another computer I see the
> "multicast membership report" packets been generated from my computer
> and when I close the program I see the "exit multicast group" messages,
> but while its running I don't seem to be able to capture the packets
> without setting my Ethernet adapter (en0) to promiscuous mode.
>
> When I run ifconfig without Wireshark running I get the following
> report:
>
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> inet 127.0.0.1 netmask 0xff000000
> inet6 ::1 prefixlen 128
> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
> gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
> stf0: flags=0<> mtu 1280
> en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> ether 00:0a:95:97:27:9e
> media: autoselect (none) status: inactive
> supported media: none autoselect 10baseT/UTP <half-duplex>
> 10baseT/UTP <full-duplex> 10baseT/UTP <full-duplex,hw-loopback>
> 100baseTX <half-duplex> 100baseTX <full-duplex> 100baseTX
> <full-duplex,hw-loopback> 1000baseT <full-duplex> 1000baseT
> <full-duplex,hw-loopback> 1000baseT <full-duplex,flow-control> 1000baseT
> <full-duplex,flow-control,hw-loopback>
> en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> ether 00:0a:95:f2:83:6a
> media: autoselect (<unknown type>) status: inactive
> supported media: autoselect
> fw0: flags=8822<BROADCAST,SMART,SIMPLEX,MULTICAST> mtu 4078
> lladdr 00:0a:95:ff:fe:97:27:9e
> media: autoselect <full-duplex> status: inactive
> supported media: autoselect <full-duplex>
>
>
> When I run Wireshark I get the following report from ifconfig:
>
>
>
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> inet 127.0.0.1 netmask 0xff000000
> inet6 ::1 prefixlen 128
> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
> gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
> stf0: flags=0<> mtu 1280
> en0: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST>
> mtu 1500
> ether 00:0a:95:97:27:9e
> media: autoselect (none) status: inactive
> supported media: none autoselect 10baseT/UTP <half-duplex>
> 10baseT/UTP <full-duplex> 10baseT/UTP <full-duplex,hw-loopback>
> 100baseTX <half-duplex> 100baseTX <full-duplex> 100baseTX
> <full-duplex,hw-loopback> 1000baseT <full-duplex> 1000baseT
> <full-duplex,hw-loopback> 1000baseT <full-duplex,flow-control> 1000baseT
> <full-duplex,flow-control,hw-loopback>
> en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> ether 00:0a:95:f2:83:6a
> media: autoselect (<unknown type>) status: inactive
> supported media: autoselect
> fw0: flags=8822<BROADCAST,SMART,SIMPLEX,MULTICAST> mtu 4078
> lladdr 00:0a:95:ff:fe:97:27:9e
> media: autoselect <full-duplex> status: inactive
> supported media: autoselect <full-duplex>
>
>
> As far as I can see the only change is the setting for en0's flags to
> promisc.
>
> Any other suggestions?? This is driving me up the wall and holding up
> our integration testing.
>
> Thanks,
>
> Alex
>
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