Hi, I'm using boost 1.35 on a Linux machine. I've written an application which creates a boost::asio::ip::udp::socket, then binds to a certain local address & port - and finally I've created an option to join a boost::asio::ip::multicast::join_group. All seems well, and I see the registration request through a network sniffer. BUT, when I try to receive packets after successfully joining the udp multicast group - I get NOTHING! Needless to say, I see tons of packets streaming through with the sniffer. What am I doing WRONG? Here's my code (just a test application): using namespace std; using namespace boost::asio; int main(int argc, char *argv[]) { if (argc != 4) { // Test for correct number of parameters cerr << "Usage: " << argv[0] << " <Local Address> <Multicast Address> <Port>" << endl; exit(1); } io_service m_io_service; ip::udp::socket m_socket(m_io_service); ip::address localAddress(ip::address_v4::from_string(argv[1])); ip::address multicastAddress(ip::address_v4::from_string(argv[2])); unsigned short port = atoi(argv[3]); // Second arg: port boost::system::error_code error; m_socket.open(ip::udp::v4()); m_socket.bind(ip::udp::endpoint(localAddress, port), error); if (error) { cout << "bind error!" << endl; exit(1); } ip::multicast::join_group option(multicastAddress.to_v4(), localAddress.to_v4()); m_socket.set_option(option); vector<unsigned char> m_receiveBuffer; mutable_buffers_1 buf = buffer((void*)&m_receiveBuffer[0], 1024); int size = (int)m_socket.receive(buf, 0, error); if (error) { cout << "recv error!" << endl; exit(1); } return 0; } Thanks! Lenny.