服务端：
        private void button1_Click(object sender, EventArgs e)
        {
             IPAddress ip = IPAddress.Parse("127.0.0.1");
            IPEndPoint ipep = new IPEndPoint(ip, 55555);
            Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);


            server.Bind(ipep);
            server.Listen(10);

            while (true)
            {
                Socket s = server.Accept();
                byte[] uspw = new Byte[1024];
                //接受  然后反序列化 
                s.Receive(uspw);
                BinaryFormatter formatter = new BinaryFormatter();
                MemoryStream stream = new MemoryStream(uspw);
               
                user us= (user)formatter.Deserialize(stream);

            }

        }

   [Serializable]
    public class user
    {
        public string userID;
        public string password;

    }

客户端：
        private void button1_Click(object sender, EventArgs e)
        {
            Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            client.Connect(IPAddress.Parse("127.0.0.1"), 55555);

            MemoryStream stream = new MemoryStream();
            IFormatter formatter = new BinaryFormatter();

            user us = new user();
            us.userID = "xiao";
            us.password = "rrr";

            formatter.Serialize(stream, us);
            stream.Flush();

            byte[] uspw = stream.ToArray();
 

            client.Send(uspw);

        }


    [Serializable]
    public class user
    {
        public string userID;
        public string password;

    }