How do I receive multicast packets?

Question

I'm trying to receive multicast packets from a media server. This is the wireshark capture of an example packet:

_{(source: memecode.com)}

There doesn't seem to be any ports involved, just MAC address for source and destination. Most of the source code examples I've seen bind against a specific port when receiving multicast packets. e.g. https://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=%2Frzab6%2Frzab6x2multicast.htm

I would like to be able to receive these packets on both Windows and MaxOSX (C++ apps in both cases, ie Win32 API and Carbon, although the Mac port is more important).

How can I do this?

Answer 1

You just create a UDP socket, bind it to the port, join the multicast group, and call recvfrom().

But the packet you captured doesn't look like a UDP multicast packet. Possibly something between the routers? It doesn't have an IP header let alone a UDP header, which is where the IP and port information is,