Who is reached by IP multicast?

Question

We have a piece of software here that seems to be phoning home quite a bit. Using wireshark we figured out that it sends quite a few UDP packets each second to 224.168.168.168. Google tells me, this is a reserved multicast IP.

Can I somehow find out who is subscribed to that multicast group?

score 2 · Accepted Answer · answered Aug 26 '15 at 16:48

Unicast is visible to the local LAN AND it is visible to any routable network that has a chain of properly configured multicast repeaters available.

NO internet provider will forward multicast packets, so the software is NOT phoning home.

You can find out who is sbscribed IF you have the infrastructure in your network to track it. If not - no. But then it is limited basically on the next router (i.e. the same subnet / ethernet broadcast domain).

Thanks a lot for that. What infrastructure would I need to track that? — Dakkaron, Aug 27 '15 at 09:49

score 1 · Answer 2 · answered Aug 26 '15 at 16:24

1

Each device on the LAN can see those packets. If you don't do multicast routing then that's where it stops.

answered Aug 26 '15 at 16:24

Sander Steffann

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The multicast address you mention is often used for multicast paging and intercom features of VoIP systems – Sander Steffann Aug 26 '15 at 16:26

Who is reached by IP multicast?

2 Answers2