IP multicast is a layer 3 protocol. Therefore, in theory, in order to filter it you'd
need a layer 3 device, (or 'router') not a layer 2 device (or 'switch'). You see,
IIRC, TTWAGOS(Take This With A Grain Of Salt), IP Multicast is mapped to an ethernet
Broadcast by the last-hop router. The idea is that from the multicast source's and
intermediate router's point of view, it is treated as (mostly)
an IP unicast packet, but when it hits a point where paths to multiple clients
diverge, the packet is duplicated on each path. When the next hop is a
shared-media(ethernet) with multiple next-hop routers or registered multicast
end-nodes, it is sent as a broadcast. This is nice if you are e.g. streaming video
and would like to only send one copy of the stream over your local T-1(which you pay
for) but you do have multiple clients that need to see the stream. Routing IP
Multicast is complex, and I will not show off any more of my ignorance about it here.
If you want more, mail me off-list. I can out-pedantify the best of them.
All that being said, it seems that most of the major network hardware vendors failed
to go to OSI model-compliant-network-device-naming schools, which could end up working
in your favor. Most modern 'network switches' of the 'managed' or 'enterprise'
classes (basically anything other than those sub $300 netgear boxes flooding the local
computer stores) DO implement various kinds of Multicast
filtering.
(Cisco and HP both do, at least). They typically can filter IPX and IP multicast and
broadcast traffic, sometimes based on even HIGHER layers of the OSI model, just to
give snits to all the entry-level network technologies instructors out there.
So short answer is 'Maybe'.
If you don't happen to have one of these fancier switches, you could try filtering out
udp packets with destination addresses of 224.10.10.10 on whatever port your receiver
is sending to. Check into ipchains. There are well-written HOW-TOs over at the ldp.
This will prevent your linux boxes from seeing this traffic, but will of course will
not prevent the traffic from taking up useless bandwidth.
Kevin Tyle wrote:
>
> Hi,
>
> We recently installed a satellite data receiver which transmits
> data over a Multicast address (224.10.10.10). I have assigned
> the receiver an IP address on our Class C address, and it is
> attached to our network switch.
>
> While this configuration allows any of our Linux machines to
> receive and process the data, I have found that the receiver's
> packets are being received by all of our systems on the network,
> according to tcpdump. This may also be responsible to some strange
> instances of "bind:address already in use" when I attempt to restart
> some network services, such as HylaFAX.
>
> Can anyone give me advice as to how to restrict the Multicast packets
> being sent on 224.10.10.10 so that they don't hit all the machines--only
> the two or so that I want? I don't really understand much about
> Multicast so I'd welcome any assistance.
>
> The receiver is preconfigured by the vendor to use Multicast so reconfiguring
> it locally is not an option.
>
> Thanks!
>
> --Kevin
>
> ---------------------------------------------------------------
>
> Kevin Tyle <[EMAIL PROTECTED]>
> MESO, Inc.
> Troy, NY
>
> _______________________________________________
> Redhat-list mailing list
> [EMAIL PROTECTED]
> https://listman.redhat.com/mailman/listinfo/redhat-list
--
-------------------------------------
Sam Bayne - System Administrator
North Seattle Community College
[EMAIL PROTECTED] (206)527-3762
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