可以看到，总的工作流程就是：

1. 服务端监听
2. 客户端（可以有多个）请求连接
3. 确认连接进行通信

针对服务器端的工作流程是：

1. 建立Socket对象
2. Bind(ip, port)绑定端口。比如说本地的(127.0.0.1, 6666)
3. Listen()开始监听
4. Accept(）接受客户端连接
5. Send（）和Receive（）进行通信
6. Close()关闭套接字

而针对客户端的工作流程是：

1. 建立Socket对象
2. Connet(ip, port)向某个IP下的PORT端口发起连接请求，接受后开始通信
3. Send()和Receive（）进行通信
4. Close() 关闭套接字

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace socket
{
    class Program
    {

        static Socket serverSocket;
      
       

        static void Main(string[] args)
        {
            SetListen();  //开始监听

        }

        static void SetListen()
        {
            serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            try
            {
                //这里最好改成IPAddress.Any, 这样放到服务器上就会同时监听所有网卡上的端口，比如有内外双网的服务器
                serverSocket.Bind(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888));
                serverSocket.Listen(2);

                Thread thread = new Thread(Listen);
                thread.Start(serverSocket);

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
           
        }

        static void Listen(object so)
        {
            Socket serverSocket = so as Socket;

            while (true)
            {
                try
                {
                    Socket clientSocket = serverSocket.Accept(); //接受客户端接入
                    // 获取链接IP地址
                    string clientPoint = clientSocket.RemoteEndPoint.ToString();

                    //开启新线程来不停接受信息
                    Thread rec = new Thread(Receive);
                    rec.Start(clientSocket);

                    //开启新线程来不停发送信息
                    Thread sen = new Thread(Send);
                    sen.Start(clientSocket);
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex.Message, ex);
                    break;
                }
            }
            serverSocket.Close();
        }

        static void Receive(object so)
        {
            Socket clientSocket = so as Socket;

            string clientPoint = clientSocket.RemoteEndPoint.ToString();
            while (true)
            {
                try
                {
                    byte[] buffer = new byte[1024];
                    int len = clientSocket.Receive(buffer);
                    //Console.WriteLine(len.ToString(), buffer);
                    if (len == 0) break;

                    string msg = Encoding.UTF8.GetString(buffer, 0, len);
                    Console.WriteLine("客户端说："+ msg);
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex);
                }
            }
        }

        static void Send(object so)
        {
            Socket clientSocket = so as Socket;

            while (true)
            {
                //获取控制台输入
                string input = Console.ReadLine();

                byte[] msg = Encoding.UTF8.GetBytes(input);
                clientSocket.Send(msg);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace socket_client
{
    class Program
    {
        static Socket clientSocket;

        static void Main(string[] args)
        {
           
            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
           
            //连接
            Connect();
        }

        //连接客户端，连接后开始监听发送过来的消息并且把输入的信息发给服务端
        static void Connect()
        {
            clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
           
            try
            {
                //连接
                clientSocket.Connect(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888));

                //独立线程来接受来自服务端的数据
                Thread receive = new Thread(Receive);
                receive.Start(clientSocket);

                //独立线程来发送数据给服务端
                Thread send = new Thread(Send);
                send.Start(clientSocket);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

        static void Receive(object so)
        {
            Socket clientSocket = so as Socket;

            while (true)
            {
                Console.ForegroundColor = ConsoleColor.Green;  // 修改文字颜色为绿色
                try
                {
                    byte[] buffer = new byte[1024];
                    int len = clientSocket.Receive(buffer);
                    if (len > 0)
                    {
                        string msg = Encoding.UTF8.GetString(buffer);
                       
                        Console.WriteLine("服务端说："+ msg);
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex);
                    break;
                }
            }
            clientSocket.Close();
        }

        static void Send(object so)
        {
            Socket clientSocket = so as Socket;

            while (true)  // 监听键盘输入
            {
                Console.ForegroundColor = ConsoleColor.Red;
                //获取键盘输入
                string input = Console.ReadLine();
                //编码
                byte[] buffer = Encoding.UTF8.GetBytes(input);
                //发送
                clientSocket.Send(buffer);
            }
        }
    }
}