C#中Udp通信问题
我在C#中，用Udp实现网络通信，用计算机向一个端口发消息后，如果想从接受消息方再消息发回来，还需要什么链接吗？下面是我写的代码，有点问题，希望大家帮我改一下！窗体就是上面一个richtextbox1,下面一个richtextbox2,最下面一个接收按钮btnReceive，一个发送按钮btnSend。两个窗体结构是一样的！麻烦大家了！
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace 个人
{
  public partial class 个人 : Form
  {
  UdpClient udpClient;
  Thread thread;

  public 个人()
  {
  InitializeComponent();
  CheckForIllegalCrossThreadCalls = false;
  udpClient = new UdpClient(13579);
  }

  private void listen()
  {
  IPEndPoint iep = null;
  while (true)
  {
  string sData = System.Text.Encoding.UTF8.GetString
  (udpClient.Receive(ref iep));
  this.richTextBox1.Text += sData;
  }
  }

  private void btnSend_Click(object sender, EventArgs e)
  {
  richTextBox1.Text += richTextBox2.Text;
  string temp = this.richTextBox2.Text;
  byte[] bData = System.Text.Encoding.UTF8.GetBytes(temp);
  udpClient.Connect(IPAddress.Parse("127.0.0.1"), 13579);
  udpClient.Send(bData, bData.Length); 
  richTextBox2.Text = null;
  richTextBox2.Focus();
  }

  private void btnReceive_Click(object sender, EventArgs e)
  {
  btnReceive.Enabled = false;
  thread = new Thread(new ThreadStart(listen));
  thread.IsBackground = true;
  thread.Start();
  }

  private void 个人_FormClosing(object sender, FormClosingEventArgs e)
  {
  if (thread != null)
  thread.Abort();
  }
  }
}


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

namespace Udp聊天
{
  public partial class 群 : Form
  {
  UdpClient udpClient;
  Thread thread;

  public 群()
  {
  udpClient = new UdpClient();
  InitializeComponent();
  CheckForIllegalCrossThreadCalls = false;
  //udpClient = new UdpClient(13579);
  }

  private void btnSend_Click(object sender, EventArgs e)
  {
  richTextBox1.Text += '\n'+this.richTextBox2.Text;
  string temp = this.richTextBox2.Text;
  byte[] bData = System.Text.Encoding.UTF8.GetBytes(temp);
  udpClient.Connect(IPAddress.Parse("127.0.0.1"), 13579);
  udpClient.Send(bData, bData.Length);
  richTextBox2.Text = null;
  richTextBox2.Focus();
  }

  private void btnReceive_Click(object sender, EventArgs e)
  {<