Unable to receive multicast on a multi network interface host

Question

Can anyone please help?
I am not able to receive multicast on a multi network interface host.
This is the code:
public class LegacyMulticast {
public static void main(String[] args) throws IOException {
InetSocketAddress group = new InetSocketAddress("224.10.20.30", 12345);
NetworkInterface iface = NetworkInterface.getByName("eth3");
MulticastSocket socket = new MulticastSocket();
socket.setSoTimeout(5000);
socket.joinGroup(group , iface);
byte[] b = new byte[4096];
DatagramPacket datagram = new DatagramPacket(b, b.length);
try {
socket.receive(datagram);
System.out.println("Success");
catch (SocketTimeoutException ste) {
System.out.println("Failure");
socket.leaveGroup(group, iface);
The funny thing is that when I start this code, Wireshark detects IGMP join on the correct network interface caused by joinGroup call, followed by constant UDP traffic on correct port which I aim to receive and finally I see correct IGMP leave caused by leaveGroup call and the UDP traffic stops.
I just don't receive anything on socket.receive call.
I am trying to figure this one out for days now. Pls help someone :)
P.S. I suspected security, but System.getSecurityManager() call returns null.
P.P.S. I also tried implementing this with NIO, but with same result.

Answer 1

public class LegacyMulticast {
public static void main(String[] args) throws IOException {
InetSocketAddress group = new InetSocketAddress("224.10.20.30", 12345);
NetworkInterface iface = NetworkInterface.getByName("eth3");
MulticastSocket socket = new MulticastSocket(12345);
socket.setSoTimeout(5000);
socket.joinGroup(group , iface);
byte[] b = new byte[4096];
DatagramPacket datagram = new DatagramPacket(b, b.length);
try {
socket.receive(datagram);
System.out.println("Success");
catch (SocketTimeoutException ste) {
System.out.println("Failure");
socket.leaveGroup(group, iface);
This is still not working.
The multicast is coming from the network (not localhost), OS is Windows 7.
When I start a multicast stream localy via VLC application on this same group and port, I receive the traffic in this Java application OK.
Once again, Wireshark detects IGMP join and leave and multicast traffic flow on eth3 network interface initiated by the Java application, but it just doesn't see the UDP datagrams.