C#利用SharpPcap实现网络包捕获嗅探

/// <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);  }