c#socket

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private TcpListener _tcplistener;        
        private Socket clientSocket;      
     
        private Thread receiveThread;
        private void button1_Click(object sender, EventArgs e)
        {
            Thread startListenThread = new Thread(new ThreadStart(StartListening));
            startListenThread.Start();
        }

        private void StartListening()
        {
            int port = 11000;
            _tcplistener = new TcpListener(port);
            _tcplistener.Start();
            while (true)
            {
                try
                {
                    Socket s = _tcplistener.AcceptSocket();
                    clientSocket = s;
                    receiveThread = new Thread(new ThreadStart(ReceiveClient));
                    receiveThread.Start();
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
            }
        }


        private void ReceiveClient()
        {
            try
            {
                Socket client = clientSocket;
                bool keepalive = true;
                while (keepalive)
                {
                    Byte[] buffer = new Byte[1024];
                    client.Receive(buffer);
                    string clientcommand = System.Text.Encoding.ASCII.GetString(buffer);
                    ShowMsg(clientcommand);
                }
                client.Close();
                keepalive = false;
            }
            catch (Exception ex)
            { }
        
        }



        delegate void ShowMsgDelegate(string str);
        private void ShowMsg(string msg)
        {
            ShowMsgDelegate ShowMsg = new ShowMsgDelegate(ShowMessage);
            this.Invoke(ShowMsg, new object[] { msg });
        }
        private void ShowMessage(string msg)
        {
            richTextBox1.AppendText(msg);
        }







    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace TcpClientTestNew
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            string message = txtSendMsg.Text;
            byte[] outbytes = System.Text.Encoding.Default.GetBytes(message.ToCharArray());
            ns.Write(outbytes, 0, outbytes.Length);
        }
        TcpClient tcpClient;       
        private NetworkStream ns;
        private void StartConnect()
        {         


           try
            {
                //
                tcpClient = new TcpClient();
                //
                tcpClient.Connect(IPAddress.Parse(txtIP.Text), Int32.Parse(txtPort.Text));
                //
                ns = tcpClient.GetStream();
                //
             
           
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            StartConnect();

        }
    }
}