服務端：

/***
 * 
 * 
 *  服務器端 
 * 
 */

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using System.Text;
using System.Threading;
using System.Net;
using System.Net.Sockets;
using UnityEngine.UI;
using System;

public class Server : MonoBehaviour
{
    
 
public InputField InpIPAdress;                              //IP地址
    public InputField InpPort;                                  //端口號
    public InputField InpDisplayInfo;                           //顯示信息
    public InputField InpSendMsg;                               //發送信息
    public Dropdown Dro_IPList;                                 //
 
客戶端的IP列表

    private Socket socketServer;                                //服務端套接字
    private bool IsListionContect;                              //是否監聽
    private StringBuilder _strDisplayInfo = new StringBuilder();//追加信息
    private string _CurClientIPValue = string.Empty;            //當前選擇的IP地址
    
 
//保存客戶端通訊的套接字
    private Dictionary<string, Socket> _DicSocket = new Dictionary<string, Socket>();
    //保存DropDown的數據，目的為了刪除節點信息
    private Dictionary<string, Dropdown.OptionData> _DicDropdowm = new Dictionary<string, Dropdown.OptionData>();

    // Start is called before the first frame update
    void Start()
    {
        //控件初始化
        InpIPAdress.text = "127.0.0.1";
        InpPort.text = "1000";
        InpSendMsg.text = string.Empty;
        
        //下拉列表處理
        Dro_IPList.options.Clear();                         //清空列表信息
        //添加一個空節點
        Dropdown.OptionData op = new Dropdown.OptionData();
        op.text = "";
        Dro_IPList.options.Add(op);
    }

    /// <summary>
    /// 退出系統
    /// </summary>
    public void ExitSystem()
    {
        if (socketServer != null)
        {
            socketServer.Shutdown(SocketShutdown.Both);     //關閉連接
            socketServer.Close();                           //清理資源
        }
        Application.Quit();
    }

    /// <summary>
    /// 獲取當前好友
    /// </summary>
    public void GetCurrentIPInformation()
    {
        //選擇玩家當前列表
        _CurClientIPValue = Dro_IPList.options[Dro_IPList.value].text;
    }

    public void EnableServerReady()
    { 
        //需要綁定地址和端口號
        IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse(InpIPAdress.text), Convert.ToInt32(InpPort.text));
        //定義監聽Socket
        socketServer = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        //綁定
        socketServer.Bind(endPoint);

        //開始socket監聽
        socketServer.Listen(10);
        //顯示內容
        //定義方法

        //開啟前臺監聽（監聽客戶端連接）
        Thread thClientCon = new Thread(ListionCilentCon);
        thClientCon.Name = "thListionClientCon";
        thClientCon.Start();
    }

    private void ListionCilentCon()
    {
        Socket socMesgServer = null;                        //會話Socket

        try
        {
            while (IsListionContect)
            {
                //等待接受客戶端連接，此處會“阻斷”當前線程
                socMesgServer = socketServer.Accept();
                //獲取遠程節點信息
                string strClientIPAndPort = socketServer.RemoteEndPoint.ToString();
                //把遠程節點信息添加到DropDown控件中
                Dropdown.OptionData op = new Dropdown.OptionData();
                op.text = strClientIPAndPort;
                Dro_IPList.options.Add(op);
                //把會話Socket添加到集合中（為後面發送信息使用）
                _DicSocket.Add(strClientIPAndPort, socMesgServer);
                //控件顯示，有客戶端連接
                
                //開啟後臺線程，接受客戶端信息
                Thread thClientMsg = new Thread(ReceivMsg);
                thClientMsg.IsBackground = true;
                thClientMsg.Name = "thListionClientMsg";
                thClientMsg.Start(socMesgServer);
            }
        }
        catch (Exception)
        {
            
            throw;
        }
    }
    /// <summary>
    /// 後臺線程，接受客戶端信息
    /// </summary>
    /// <param name="sockMsg"></param>
    private void ReceivMsg(object sockMsg)
    { 
    
    }

    // Update is called once per frame
    void Update()
    {
        
    }
}

Unity 網絡編程(Socket)應用