服务端代码
static void Main(string[] args)
        {
            Socket server_socket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);

            IPAddress  ips = IPAddress.Parse("127.0.0.1");
            IPEndPoint ipNode = new IPEndPoint(ips,6666);
            server_socket.Bind(ipNode);
            server_socket.Listen(40);            
            Console.WriteLine("wait a client.....");
            Thread acceptThread = new Thread(AcceptThread);
            acceptThread.Start(server_socket);            
        }
        static void AcceptThread(object obj)
        {
            Socket server_socket = (Socket)obj;
            while (true)
            {
                Socket client = server_socket.Accept();
                Thread recvThread = new Thread(RecvThread);
                Thread sendThread = new Thread(SendThread);
                recvThread.Start(client);
                sendThread.Start(client);   
            }
                    
        }
        static void RecvThread(object client)
        {            
            Socket clients = (Socket)client;
            while (true)
            {
                try
                {
                    byte[] buffer = new byte[1024 * 1024];
                    int num = clients.Receive(buffer);
                    string str = Encoding.ASCII.GetString(buffer, 0, num);
                    Console.WriteLine(clients.RemoteEndPoint.ToString() + " : " + str);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message+"65");
                }
               
            }
        }
        static void SendThread(object objClient)
        {
            Socket client = (Socket)objClient;

            try
            {
                byte[] data = new byte[1024];
                int recv = 0;
                string server_msg = "welcome! " + Thread.CurrentThread.ManagedThreadId;
                data = Encoding.ASCII.GetBytes(server_msg);
                client.Send(data, data.Length, SocketFlags.None);
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.Message+"85");
            }
        }

 static void Main(string[] args)
        {
            Socket client_socket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            string ip = "127.0.0.1";
            IPAddress ipAdress = IPAddress.Parse(ip);
            IPEndPoint ipEndpoint = new IPEndPoint(ipAdress,6666);
            client_socket.Connect(ipEndpoint);
            Thread recvThread = new Thread(RecvThread);
            recvThread.Start(client_socket);
            Thread sendThread = new Thread(SendThread);
            sendThread.Start(client_socket);
        }
        static void RecvThread(object obj)
        {
            Socket client_socket = (Socket)obj;
            try
            {
                byte[] data = new byte[1024];
                int recv = 0;
                recv = client_socket.Receive(data);
                string msg;
                msg = Encoding.ASCII.GetString(data, 0, recv);

                Console.WriteLine(msg + "客户端2");
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.Message);
            }
               
              
           
        }
        static void SendThread(object obj)
        {
            Socket client_socket = (Socket)obj;

            byte[] data = new byte[1024];

            string msg = "收到服务端消息 客户端2";

            data = Encoding.ASCII.GetBytes(msg);
            try
            {
                client_socket.Send(data, data.Length, SocketFlags.None);
            }
            catch(Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }