title: C# socket server refuses the connection from a python client
body: <p>I am just getting started with C# , and I was trying to make a socket server that can receive connections from python client, however server keep on refusing to connect.</p>
  <p><strong>Here is server code :</strong></p>
  <pre><code>using System;
  using System.Net;
  using System.Net.Sockets;
  using System.Text;
  using System.Threading;
  
  // State object for reading client data asynchronously  
  public class StateObject
  {
      // Size of receive buffer.  
      public const int BufferSize = 1024;
  
      // Receive buffer.  
      public byte[] buffer = new byte[BufferSize];
  
      // Received data string.
      public StringBuilder sb = new StringBuilder();
  
      // Client socket.
      public Socket workSocket = null;
  }
  
  public class AsynchronousSocketListener
  {
      // Thread signal.  
      public static ManualResetEvent allDone = new ManualResetEvent(false);
  
      public AsynchronousSocketListener()
      {
      }
  
      public static void StartListening()
      {
          // Establish the local endpoint for the socket.  
     
          IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
          IPAddress ipAddress = ipHostInfo.AddressList[0];
          IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 45545);
  
          // Create a TCP/IP socket.  
          Socket listener = new Socket(ipAddress.AddressFamily,
              SocketType.Stream, ProtocolType.Tcp);
  
          // Bind the socket to the local endpoint and listen for incoming connections.  
          try
          {
              listener.Bind(localEndPoint);
              listener.Listen(100);
  
              while (true)
              {
                  // Set the event to nonsignaled state.  
                  allDone.Reset();
  
                  // Start an asynchronous socket to listen for connections.  
                  Console.WriteLine(&quot;Waiting for a connection...&quot;);
                  listener.BeginAccept(
                      new AsyncCallback(AcceptCallback),
                      listener);
  
                  // Wait until a connection is made before continuing.  
                  allDone.WaitOne();
              }
  
          }
          catch (Exception e)
          {
              Console.WriteLine(e.ToString());
          }
  
          Console.WriteLine(&quot;\nPress ENTER to continue...&quot;);
          Console.Read();
  
      }
  
      public static void AcceptCallback(IAsyncResult ar)
      {
          // Signal the main thread to continue.  
          allDone.Set();
  
          // Get the socket that handles the client request.  
          Socket listener = (Socket)ar.AsyncState;
          Socket handler = listener.EndAccept(ar);
  
          // Create the state object.  
          StateObject state = new StateObject();
          state.workSocket = handler;
          handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
              new AsyncCallback(ReadCallback), state);
      }
  
      public static void ReadCallback(IAsyncResult ar)
      {
          String content = String.Empty;
  
          // Retrieve the state object and the handler socket  
          // from the asynchronous state object.  
          StateObject state = (StateObject)ar.AsyncState;
          Socket handler = state.workSocket;
  
          // Read data from the client socket.
          int bytesRead = handler.EndReceive(ar);
  
          if (bytesRead &gt; 0)
          {
              // There  might be more data, so store the data received so far.  
              state.sb.Append(Encoding.ASCII.GetString(
                  state.buffer, 0, bytesRead));
  
              // Check for end-of-file tag. If it is not there, read
              // more data.  
              content = state.sb.ToString();
              if (content.IndexOf(&quot;&lt;EOF&gt;&quot;) &gt; -1)
              {
                  // All the data has been read from the
                  // client. Display it on the console.  
                  Console.WriteLine(&quot;Read {0} bytes from socket. \n Data : {1}&quot;,
                      content.Length, content);
                  // Echo the data back to the client.  
                  Send(handler, content);
              }
              else
              {
                  // Not all data received. Get more.  
                  handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                  new AsyncCallback(ReadCallback), state);
              }
          }
      }
  
      private static void Send(Socket handler, String data)
      {
          // Convert the string data to byte data using ASCII encoding.  
          byte[] byteData = Encoding.ASCII.GetBytes(data);
  
          // Begin sending the data to the remote device.  
          handler.BeginSend(byteData, 0, byteData.Length, 0,
              new AsyncCallback(SendCallback), handler);
      }
  
      private static void SendCallback(IAsyncResult ar)
      {
          try
          {
              // Retrieve the socket from the state object.  
              Socket handler = (Socket)ar.AsyncState;
  
              // Complete sending the data to the remote device.  
              int bytesSent = handler.EndSend(ar);
              Console.WriteLine(&quot;Sent {0} bytes to client.&quot;, bytesSent);
  
              handler.Shutdown(SocketShutdown.Both);
              handler.Close();
  
          }
          catch (Exception e)
          {
              Console.WriteLine(e.ToString());
          }
      }
  
      public static int Main(String[] args)
      {
          StartListening();
          return 0;
      }
  }
  </code></pre>
  <p><strong>and here is Python Client :</strong></p>
  <pre><code>import socket
  import time
  from datetime import datetime
  clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM);
  clientSocket.connect(('localhost',45545));
  time.sleep(10000);
  </code></pre>
  <p>initially the python client was supposed to send some data to the server but then i noticed that connection isnt being established , so i removed the part where its sending the data and only using the code that is responsible for establishing the connection.</p>
  <p><strong>Here is what is am receiving at the python client side :</strong></p>
  <p><a href="https://i.stack.imgur.com/A4kdn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/A4kdn.png" alt="enter image description here" /></a></p>
  <p>I am not sure whats going on , but is it possible that server is refusing the connection because the client is not a C# client and is a python client ?</p>