C#

private void btnstartserver_Click(object sender, EventArgs e)
    {

        int portno = Convert.ToInt32(txtportnum.Text);
        byte[] receivedBytes = new byte[1024];
        IPHostEntry ipHost = Dns.GetHostEntry(Dns.GetHostName());
        IPAddress ipAddress = ipHost.AddressList[0];
        IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, portno);//2112
        txtboxstatus.Text = "Creating socket object...";

        Socket listener = new Socket(AddressFamily.InterNetworkV6,
                                    SocketType.Stream,
                                    ProtocolType.Tcp);

        listener.Bind(ipEndPoint);
        listener.Listen(10);
        txtboxstatus.AppendText("Listening on " + ipHost.AddressList[0].ToString() + ":" + portno.ToString() + "\r\n");


        Socket socket = listener.Accept();

        txtboxstatus.AppendText ( "\n Connected with ..." + ipEndPoint.Port);

        string receivedvalue = string.Empty;


        receivedvalue = ReadMessage(socket);
        txtboxstatus.AppendText("\n Message read.....trying to write to the file...");
        //writing the received value from client into a file.
        try
        {
            FileStream fs = new FileStream("E:/Demo/IpData/Call.txt", FileMode.Create);
            StreamWriter sw = new StreamWriter(fs);
            sw.Write(receivedvalue);
            sw.Dispose();
            fs.Dispose();
        }
        catch (Exception ex)
        {
            txtclient.AppendText(ex.Message); 
        }  
     }