CODEWITHSUNDEEP
socketsudpmulticast
denvercoder
denvercoder

Reputation: 1

How to find out if a multicast packet is addressed to a specific host?

I have wireshark records of an interface on a host machine. In these records, there are several multicast packages which has multicast group ip address (ex. 224.0.20.30) as destination and multicast message originator ip as source. How can I be sure that the packets I received using wireshark on this network interface is actually addressed to this host machine?

I tried checking layer 2 destination and source fields. For my outgoing multicast packets, source is my network interface card mac address and destination is 01:00:5e followed by 23 bits of multicast group address. But for packets whose originators are different hosts, destination is still the same but source is a different address.

Does receiving a packet using wireshark ensure that said package is addressed to this host machine?

Upvotes: 0

Views: 270

Answers (1)

Steffen Ullrich
Steffen Ullrich

Reputation: 123531

How to find out if a multicast packet is addressed to a specific host?

The very point of multicast is that it a packet not addressed to a specific host but that a single packet has many hosts at once as a target. It depends on the software on the hosts if the packet will then be used for some application or if it will be simply ignored.

Does receiving a packet using wireshark ensure that said package is addressed to this host machine?

If promiscuous mode is enabled on the interface (and Wireshark usually is configured to do this) then it will also see packets which are not explicitly addressed to the host but will still arrive at the network card. Note that in environments with a network switch mostly packets arrive at the system which are designed to the processed by the system though.

Upvotes: 0

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