I'm trying to devise a way for ROS to accept an incoming UDP unicast stream on one interface and send it out another interface as multicast.

In this application, the input and output interfaces are both wifi. I control the programs generating the packets at the source and receiving the packets on multiple devices at the destination.

I could generate the original traffic as multicast, but this is an unreliable transmission method and packets will be lost going from the source via wifi to the router. I realize that the multicast link out of the router is also unreliable, but I at least want the incoming packets to arrive more-or-less intact, hence the desire for unicast on the way in.

I thought perhaps I could use a mangle rule, but there doesn't seem to be a way to re-write the destination address.

I also thought about some kind of NAT, but I'm not sure what to do with that.

Some odd routing rule maybe?

Any ideas out there?

I don't think you can do that with NAT

in v6 there's possibility to send multicast packets as unicast transmission via wireless, AFAIR