Receiving broadcast messages

Posted by Prasad on Stack Overflow See other posts from Stack Overflow or by Prasad
Published on 2010-03-27T17:25:22Z Indexed on 2010/03/27 17:33 UTC
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Hi,

I'm trying to receive broadcast messages using C# code in an ISDN network with BRI interface at my end.

I see the packets sent to the broadcast ip address (239.255.255.255) on some ports using Comm View tool.

But when I try to listen to this IP address, it says the address is not in a valid context.

But when I send broadcast messages to 255.255.255.255 on a port, I can receive those messages with the below code..

What could be the problem with this ip address - 239.255.255.255 ?

The code I use to listen to broadcast messages is..

UdpClient udp = new UdpClient();
IPEndPoint receiveEndPoint = new IPEndPoint(IPAddress.Any, 8013);
// If I use IPAddress.Parse("239.255.255.255") to listen to,
// it says "the address is not in a valid // context."
udp.Client.Bind(receiveEndPoint);
udp.BeginReceive(_Callback, udp);

static private void _Callback(IAsyncResult iar)
{
        try
        {
            UdpClient client = (UdpClient)iar.AsyncState;

            client.BeginReceive(_Callback, client);

            IPEndPoint ipRemote = new IPEndPoint(IPAddress.Any, 8013);

            byte[] rgb = client.EndReceive(iar, ref ipRemote);

            Console.WriteLine("Received {0} bytes: \"{1}\"",
            rgb.Length.ToString(), Encoding.UTF8.GetString(rgb));
        }
        catch (ObjectDisposedException)
        {
            Console.WriteLine("closing listening socket");
        }
        catch (Exception exc)
        {
            Console.WriteLine("Listening socket error: \"" +
            exc.Message + "\"");
        }
 }

There are packets sent to the broadcast ipaddress (239.255.255.255) which I can see in Commview tool, but can't receive them from the code...

Can anybody help me out please?

Thanking you in advance,
Prasad Kancharla.

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