[Godel_unicode]

Group membership matters in multicast, although I agree probably not in this case. If there's a hub-spoke topology and you a spoofing on a leaf switch which doesn't propagate this could be a fun problem for engineering (looking up and reading about IGMP is left as an exercise for the reader)

[chris_wot]

Well, it doesn't appear that IP spoofing has been setup too well on the switches, because the switch seems to be doing what either an el cheapo switch will do, or do what Cisco switches do which is take the multicast traffic and flood it out the vlan broadcast domain.

Hell, if that's UDP traffic it doesn't necessarily even look like it requires a response, so you could spoof the source IP address and the server might not even care...