read multicast packets from node

index.js

var socket = dgram.createSocket({ type: 'udp4', reuseAddr: true })
socket.bind(5004, function () {
  socket.addMembership('239.255.42.42', getIpForInterface('en2'))
  socket.setMulticastTTL(255)
})

socket.on('message', function (m) {
  // m is a buffer
})

function getIpForInterface (ifname) {
  return os.networkInterfaces()[ifname].reduce(function (i, j) {
    if (i.family === 'IPv4') return i
    return j
  }).address  
}