You don't happen to be running "avahi" or one of the other Zeroconf/
Bonjour/Rendezvous/$P2P_BUZZWORD_OF_THE_WEEK local-network-discovery
daemons, do you? Most of those keep an eye out for new network
interfaces and automatically start pushing multicast packets down
them as soon as they appear, which is the most likely explanation for
what you are seeing; as opposed to a kernel issue.
Cheers,
Kyle Moffett
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