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：

1. 通过进程名字获取对应的端口号。
2. 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);
        }

关于SharpPcap手册

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