Change multicast address to private network

Multicast addresses in the 239.0.0.0/8 range are designated for private networks and are not to be routed over the public Internet. In practice however, multicast generally doesn't get routed over the Internet anyway as it's only seen limited use, and most routers won't pass multicast traffic by default. So you can probably get away with using any valid multicast address without worrying about it getting out of your network.