UDP: reading data from all network interfaces

Question

I have the following code to read a multicast message coming from the network for the specified IP + port

private static void ReceiveMessages(int port, string ip, CancellationToken token)
{
    Task.Factory.StartNew(() =>
        {
            using (var mUdpClientReceiver = new UdpClient())
            {
                var mReceivingEndPoint = new IPEndPoint(IPAddress.Any, port);
                mUdpClientReceiver.ExclusiveAddressUse = false;
                mUdpClientReceiver.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                mUdpClientReceiver.ExclusiveAddressUse = false;
                mUdpClientReceiver.Client.Bind(mReceivingEndPoint);
                mUdpClientReceiver.JoinMulticastGroup(IPAddress.Parse(ip), 255);

                while (!token.IsCancellationRequested)
                {
                    byte[] receive = mUdpClientReceiver.Receive(ref mReceivingEndPoint);

                    Console.WriteLine("Message received from {0} ",mReceivingEndPoint);
                }
            }
        });
}

I have two network adapters, of which I have data coming to this multicast ip + port (confirmed by two wirehark instances that track each network adapter). I see on the wires a lot of traffic going on these ports + Ip) for both network cards.

The problem is that on my console I see only messages coming from one network card.

I double-checked netstat, I have no other software listening on my port:

So why do I only get traffic from one of the two network cards?

EDIT

I even tried the following:

private static void ReceiveMessages(int port, string ip, CancellationToken token, IEnumerable<IPAddress> ipAddresses)
{
    foreach (IPAddress ipAddress in ipAddresses)
    {
        IPAddress ipToUse = ipAddress;
        Task.Factory.StartNew(() =>
        {
            using (var mUdpClientReceiver = new UdpClient())
            {

                var mReceivingEndPoint = new IPEndPoint(ipToUse, port);
                mUdpClientReceiver.ExclusiveAddressUse = false;
                mUdpClientReceiver.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                mUdpClientReceiver.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
                mUdpClientReceiver.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.DontRoute, 1);
                mUdpClientReceiver.ExclusiveAddressUse = false;
                mUdpClientReceiver.Client.Bind(mReceivingEndPoint);
                mUdpClientReceiver.JoinMulticastGroup(IPAddress.Parse(ip), 255);
                Console.WriteLine("Starting to listen on "+ipToUse);
                while (!token.IsCancellationRequested)
                {
                    byte[] receive = mUdpClientReceiver.Receive(ref mReceivingEndPoint);

                    Console.WriteLine("Message received from {0} on {1}",  mReceivingEndPoint,ipToUse);
                }
            }
        });
    }
}

" CorrectIP" ( IP-), - , .

2

- , . , , , . , .

, , , ( )

3

: (localhost), , , , . , , , .

4

, : ethernet, 10.10.24.78 ip, - 10.9.10.234 ip. , , ( 5353 ip - , mDNS, , , itunes, macs , ). ip   224.0.0.251 5353.

, IP-, , , , ( , ).

private static void SendManuallyOnAllCards(int port, string multicastAddress, IEnumerable<IPAddress> ipAddresses)
{
    foreach (IPAddress remoteAddress in ipAddresses)
    {
        IPAddress ipToUse = remoteAddress;
        using (var mSendSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp))
        {
            mSendSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership,
                                        new MulticastOption(IPAddress.Parse(multicastAddress)));
            mSendSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, 255);
            mSendSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

            var ipep = new IPEndPoint(ipToUse, port);
            //IPEndPoint ipep = new IPEndPoint(IPAddress.Parse(multicastAddress), port);
            mSendSocket.Bind(ipep);
            mSendSocket.Connect(ipep);


            byte[] bytes = Encoding.ASCII.GetBytes("This is my welcome message");
            mSendSocket.Send(bytes, bytes.Length, SocketFlags.None);
        }
    }
}

5 route print ( ), IP- 10.9.10.234

6

:

• UdpClient →
• socketOption (DontRoute = 1, Broadcast = 1) →
• MulticastInterface, ( socketOption MulticastInterface) →

Answer 1

- , !

, , , !!! , ( - , :))

3 , , :

private static void ReceiveAsync(int port, string address, IEnumerable<IPAddress> localAddresses)
{
    IPAddress multicastAddress = IPAddress.Parse(address);
    foreach (IPAddress localAddress in localAddresses)
    {
        var udpClient = new UdpClient(AddressFamily.InterNetwork);
        udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        udpClient.Client.Bind(new IPEndPoint(localAddress, port));
        udpClient.JoinMulticastGroup(multicastAddress, localAddress);
        udpClient.BeginReceive(OnReceiveSink,
                               new object[]
                                   {
                                       udpClient, new IPEndPoint(localAddress, ((IPEndPoint) udpClient.Client.LocalEndPoint).Port)
                                   });
    }
}

async:

private static void OnReceiveSink(IAsyncResult result)
{
    IPEndPoint ep = null;
    var args = (object[]) result.AsyncState;
    var session = (UdpClient) args[0];
    var local = (IPEndPoint) args[1];

    byte[] buffer = session.EndReceive(result, ref ep);
    //Do what you want here with the data of the buffer

    Console.WriteLine("Message received from " + ep + " to " + local);

    //We make the next call to the begin receive
    session.BeginReceive(OnReceiveSink, args);
}

, ;)

Answer 2

. IGMP JOIN , " " , , NIC . ​​ , .

Answer 3

, . EJP, JoinMulticastGroup(IPAddress multicastAddr, IPAddress localAddress) UdpClient :

int port = 1036;
IPAddress multicastAddress = IPAddress.Parse("239.192.1.12");

client = new UdpClient(new IPEndPoint(IPAddress.Any, port));

// list of UdpClients to send multicasts
List<UdpClient> sendClients = new List<UdpClient>();

// join multicast group on all available network interfaces
NetworkInterface[] networkInterfaces = NetworkInterface.GetAllNetworkInterfaces();

foreach (NetworkInterface networkInterface in networkInterfaces)
{
    if ((!networkInterface.Supports(NetworkInterfaceComponent.IPv4)) ||
        (networkInterface.OperationalStatus != OperationalStatus.Up))
    {
        continue;
    }

    IPInterfaceProperties adapterProperties = networkInterface.GetIPProperties();
    UnicastIPAddressInformationCollection unicastIPAddresses = adapterProperties.UnicastAddresses;
    IPAddress ipAddress = null;

    foreach (UnicastIPAddressInformation unicastIPAddress in unicastIPAddresses)
    {
        if (unicastIPAddress.Address.AddressFamily != AddressFamily.InterNetwork)
        {
            continue;
        }

        ipAddress = unicastIPAddress.Address;
        break;
    }

    if (ipAddress == null)
    {
        continue;
    }

    client.JoinMulticastGroup(multicastAddress, ipAddress);

    UdpClient sendClient = new UdpClient(new IPEndPoint(ipAddress, port));
    sendClients.Add(sendClient);
}

I also create a list of UdpClients so that I can send my multicast messages on all network interfaces.