C#利用SharpPcap实现网络包捕获嗅探

本文是利用SharpPcap实现网络包的捕获的小例子，实现了端口监控，数据包捕获等功能，主要用于学习分享。

什么是SharpPcap？

SharpPcap 是一个.NET 环境下的网络包捕获框架，基于著名的 pcap/WinPcap 库开发。提供了捕获、注入、分析和构建的功能，适用于 C# 和 VB NET 开发语言。

SharpPcap有两部分组成：1> SharpPcap.dll 负责数据的捕获  2> PacketDotNet.dll负责数据包的解析

思路：

通过进程名字获取对应的端口号。
SharpPcap获取对应的数据包，通过解析数据包过滤相关的端口。

涉及知识点：

Process 获取相关进程信息。
netstat命令：netstat -ano|find "3844" 获取进程对应的端口
SharpPcap相关信息：

通过CaptureDeviceList的静态方法获取设备列表。
       通过OnPacketArrival事件接收数据包。
       通过PacketDotNet来解析数据包

效果图下：

SharpPcap核心代码：

/// <summary>
  /// 开始捕捉
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void btnStart_Click(object sender, EventArgs e)
  {
   if (this.combDevice.SelectedIndex > -1)
   {
    StartCapture(this.combDevice.SelectedIndex);
    this.btnStart.Enabled = false;
    this.btnStop.Enabled = true;
   }
   else {
    MessageBox.Show(this,"请选择一个设备","提示",MessageBoxButtons.OK);
   }
  }

  /// <summary>
  /// 停止捕捉
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void btnStop_Click(object sender, EventArgs e)
  {
   Shutdown();
   this.btnStop.Enabled = false;
   this.btnStart.Enabled = true;
  }

  private void StartCapture(int itemIndex)
  {
   packetCount = 0;
   device = CaptureDeviceList.Instance[itemIndex];
   packetStrings = new Queue<PacketWrapper>();
   bs = new BindingSource();
   dgvData.DataSource = bs;
   LastStatisticsOutput = DateTime.Now;

   // start the background thread
   backgroundThreadStop = false;
   backgroundThread = new Thread(BackgroundThread);
   backgroundThread.Start();

   // setup background capture
   device.OnPacketArrival += new PacketArrivalEventHandler(device_OnPacketArrival);
   device.OnCaptureStopped += new CaptureStoppedEventHandler(device_OnCaptureStopped);
   device.Open();

   // tcpdump filter to capture only TCP/IP packets
   string filter = "ip and tcp";
   device.Filter = filter;

   // force an initial statistics update
   captureStatistics = device.Statistics;
   UpdateCaptureStatistics();

   // start the background capture
   device.StartCapture();

   btnStop.Enabled = true;
  }

  /// <summary>
  /// 设备接收事件
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void device_OnPacketArrival(object sender, CaptureEventArgs e)
  {
   // print out periodic statistics about this device
   var Now = DateTime.Now;
   var interval = Now - LastStatisticsOutput;
   if (interval > new TimeSpan(0, 0, 2))
   {
    Console.WriteLine("device_OnPacketArrival: " + e.Device.Statistics);
    captureStatistics = e.Device.Statistics;
    statisticsUiNeedsUpdate = true;
    LastStatisticsOutput = Now;
   }

   lock (QueueLock)
   {
    PacketQueue.Add(e.Packet);
   }
  }

  /// <summary>
  /// 设备停止事件
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="status"></param>
  private void device_OnCaptureStopped(object sender, CaptureStoppedEventStatus status)
  {
   if (status != CaptureStoppedEventStatus.CompletedWithoutError)
   {
    MessageBox.Show("Error stopping capture", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
   }
  }

  private void UpdateCaptureStatistics()
  {
   tlblStatistic.Text = string.Format("接收包: {0}, 丢弃包: {1}, 接口丢弃包: {2}", captureStatistics.ReceivedPackets,captureStatistics.DroppedPackets, captureStatistics.InterfaceDroppedPackets);
  }

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