Socket.BeginDisconnect Method (Boolean, AsyncCallback, Object)


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Begins an asynchronous request to disconnect from a remote endpoint.

Namespace:   System.Net.Sockets
Assembly:  System (in System.dll)

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public IAsyncResult BeginDisconnect(
	bool reuseSocket,
	AsyncCallback callback,
	object state


Type: System.Boolean

true if this socket can be reused after the connection is closed; otherwise, false.

Type: System.AsyncCallback

The AsyncCallback delegate.

Type: System.Object

An object that contains state information for this request.

Return Value

Type: System.IAsyncResult

An IAsyncResult object that references the asynchronous operation.

Exception Condition

The operating system is Windows 2000 or earlier, and this method requires Windows XP.


The Socket object has been closed.


An error occurred when attempting to access the socket. See the Remarks section for more information.

If you are using a connection-oriented protocol, you can call the BeginDisconnect method to request a disconnect from a remote endpoint. If reuseSocket is true, you can reuse the socket.

The BeginDisconnect method uses a separate thread to invoke the specified callback method. The EndDisconnect method blocks until the pending disconnect is complete. For additional information on writing callback methods, see Marshaling a Delegate as a Callback Method.


If you receive a SocketException exception, use the SocketException.ErrorCode property to obtain the specific error code. After you have obtained this code, refer to the Windows Sockets version 2 API error code documentation in the MSDN library for a detailed description of the error.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

The following code example creates a socket for asynchronous communication and sends some data to a remote host. When the data has been sent, Shutdown is called to stop the send and receive activity. Then BeginDisconnect is called to begin a disconnect request. When the request completes, the Connected property is queried to test whether the socket is disconnected.

    // Establish the remote endpoint for the socket.
    // For this example use local computer.
    IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
    IPAddress ipAddress = ipHostInfo.AddressList[0];
    IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);

    // Create a TCP/IP socket.
    Socket client = new Socket(AddressFamily.InterNetwork,
        SocketType.Stream, ProtocolType.Tcp);

    // Connect to the remote endpoint.
        new AsyncCallback(ConnectCallback), client);

    // Wait for connect.

    // Send some data to the remote device.
    string data = "This is a string of data <EOF>";
    byte[] buffer = Encoding.ASCII.GetBytes(data);
    client.BeginSend(buffer, 0, buffer.Length, 0, new AsyncCallback(ClientSendCallback), client);
    // Wait for send done.

    // Release the socket.
    client.BeginDisconnect(true, new AsyncCallback(DisconnectCallback), client);

    // Wait for the disconnect to complete.
    if (client.Connected)
        Console.WriteLine("We're still connected");
        Console.WriteLine("We're disconnected");

private static void DisconnectCallback(IAsyncResult ar)
    // Complete the disconnect request.
    Socket client = (Socket) ar.AsyncState;

    // Signal that the disconnect is complete.

.NET Framework
Available since 2.0
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