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.NET Forum / .NET Framework / New Users / January 2007

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UDP Server (what's wrong?)

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Nick - 11 Jan 2007 05:16 GMT
I have written a simple UDP server. It uses a single socket and sends
incoming data to random ports on the same machine. After second call of
Receive () I got SocketException "An existing connection was forcibly
closed by the remote host". How it can be? I have UDP server and there
are no connections!

Also I noticed if I comment out SendTo or change SendTo IP to some real
IP then the server works perfectly. What can be wrong with this?

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Net;
using System.Net.Sockets;

namespace UdpTest
{
   class Program
   {
       private static string serverIP = "192.168.64.66";
       private static int serverPort = 5000;

       static void Main(string[] args)
       {
           Thread thread = new Thread(new ThreadStart(ServerThread));
           thread.Start();

           using (UdpClient client = new UdpClient())
           {
               client.Connect(serverIP, 5000);
               while (true)
               {
                   client.Send(new byte[100], 100);
                   Thread.Sleep(1000);
               }
           }
       }

       private static void ServerThread()
       {
           using (Socket socket = new
Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp))
           {
               socket.Bind(new IPEndPoint(0, serverPort));

               byte[] buffer = new byte[65536];
               while (true)
               {
                   int read = socket.Receive(buffer);
                   if (read > 0)
                   {
                       int sent = 0;
                       for (int i = 0; i < 10; i++)
                       {
                           int port = new Random().Next(10000, 11000);
                           EndPoint point = new
IPEndPoint(IPAddress.Parse(serverIP), port);
                           sent += socket.SendTo(buffer, 0, read,
SocketFlags.None, point);
                       }
                       Console.WriteLine("Received {0} bytes, sent {1}
bytes", read, sent);
                   }
               }
           }
       }
   }
}
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Nick - 11 Jan 2007 05:19 GMT
Here's the socket log

System.Net.Sockets Verbose: 0 : [3244]
Socket#58225482::Socket(InterNetwork#2)
System.Net.Sockets Verbose: 0 : [4012]
Socket#21950498::Socket(InterNetwork#2)
System.Net.Sockets Verbose: 0 : [3244] Exiting
Socket#58225482::Socket()
System.Net.Sockets Verbose: 0 : [3244]
DNS::GetHostAddresses(192.168.64.66)
System.Net.Sockets Verbose: 0 : [3244] Exiting DNS::GetHostAddresses()
    -> IPAddress[]#54267293
System.Net.Sockets Verbose: 0 : [3244]
Socket#58225482::Connect(66:5000#1111538504)
System.Net.Sockets Verbose: 0 : [4012] Exiting
Socket#21950498::Socket()
System.Net.Sockets Verbose: 0 : [4012]
Socket#21950498::Bind(0:5000#5000)
System.Net.Sockets Verbose: 0 : [4012] Exiting Socket#21950498::Bind()
System.Net.Sockets Verbose: 0 : [4012] Socket#21950498::Receive()
System.Net.Sockets Verbose: 0 : [3244] Exiting
Socket#58225482::Connect()
System.Net.Sockets Verbose: 0 : [3244] Socket#58225482::Send()
System.Net.Sockets Verbose: 0 : [4012] Data from
Socket#21950498::Receive
System.Net.Sockets Verbose: 0 : [4012] 00000000 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000010 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000020 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000030 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000040 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000050 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000060 : 00 00 00 00
                         : ....
System.Net.Sockets Verbose: 0 : [4012] Exiting
Socket#21950498::Receive()     -> 100#100
System.Net.Sockets Verbose: 0 : [4012] Socket#21950498::SendTo()
System.Net.Sockets Verbose: 0 : [4012] Data from
Socket#21950498::SendTo
System.Net.Sockets Verbose: 0 : [4012] 00000000 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000010 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000020 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000030 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000040 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000050 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [4012] 00000060 : 00 00 00 00
                         : ....
System.Net.Sockets Verbose: 0 : [4012] Exiting
Socket#21950498::SendTo()     -> 100#100
System.Net.Sockets Verbose: 0 : [4012] Socket#21950498::Receive()
System.Net.Sockets Error: 0 : [4012] Exception in the
Socket#21950498::Receive - An existing connection was forcibly closed
by the remote host
System.Net.Sockets Verbose: 0 : [4012] Exiting
Socket#21950498::Receive()     -> 0#0
System.Net.Sockets Verbose: 0 : [3244] Data from Socket#58225482::Send
System.Net.Sockets Verbose: 0 : [3244] 00000000 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000010 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000020 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000030 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000040 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000050 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000060 : 00 00 00 00
                         : ....
System.Net.Sockets Verbose: 0 : [3244] Exiting Socket#58225482::Send()
    -> 100#100
System.Net.Sockets Verbose: 0 : [3244] Socket#58225482::Send()
System.Net.Sockets Verbose: 0 : [3244] Data from Socket#58225482::Send
System.Net.Sockets Verbose: 0 : [3244] 00000000 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000010 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000020 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000030 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000040 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000050 : 00 00 00 00 00 00 00
00-00 00 00 00 00 00 00 00 : ................
System.Net.Sockets Verbose: 0 : [3244] 00000060 : 00 00 00 00
                         : ....
System.Net.Sockets Verbose: 0 : [3244] Exiting Socket#58225482::Send()
    -> 100#100
System.Net.Sockets Verbose: 0 : [4012] Socket#21950498::Dispose()
Reply to this Message
Nick - 11 Jan 2007 07:53 GMT
Resolved
http://blog.devstone.com/aaron/archive/2005/02/20.aspx
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