C# Pcap.net communication

问题

I would like to ask why is my communicator receiving sent frames. I'm trying to fix this problem using flag PacketDeviceOpenAttributes.NoCaptureLocal for receiving communicator but I'm still receiving sent frames. Could anyone know how to fix this problem? Thank you. Here is my code:

using PcapDotNet.Core;
using PcapDotNet.Packets;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace PSIP
{
    public partial class Form2 : Form
    {
    private Packet packet;
    private List<Packet> buffer;
    private IList<LivePacketDevice> allDevices;
    private LivePacketDevice selectedDevice, sendDevice;
    private int pkt_cnt;
    private Thread thrReceive,thrSend;
    public Form2(LivePacketDevice device)
    {
        InitializeComponent();
        Show();
        selectedDevice = device;
        pkt_cnt = 0;
        buffer = new List<Packet>();
        allDevices = LivePacketDevice.AllLocalMachine;

        for (int i = 0; i != allDevices.Count; ++i)
        {
            LivePacketDevice tempDevice = allDevices[i];
            if (device.Description != null)
            {
                ListViewItem row = new ListViewItem(tempDevice.Name);
                listDevices.Items.Add(row);
            }
        }
    }

    private void PacketHandler(object obj)
    {
        throw new NotImplementedException();
    }

    private void PacketHandler(Packet packet)
    {
        ListViewItem itemPacket = new ListViewItem(pkt_cnt.ToString());
        itemPacket.SubItems.Add(packet.Ethernet.Destination.ToString());
        itemPacket.SubItems.Add(packet.Ethernet.Source.ToString());

        pktView.Items.Add(itemPacket);
        buffer.Add(packet);
        pkt_cnt++;
    }

    private void Sending()
    {
        for (int i = 0; i <= allDevices.Count; ++i)
        {
            sendDevice = allDevices[i];
            if (sendDevice.Name.Equals(listDevices.SelectedItems[0].Text))
            {
                i = allDevices.Count;
            }
        }
        using (PacketCommunicator communicator = sendDevice
        .Open(100, PacketDeviceOpenAttributes.Promiscuous | PacketDeviceOpenAttributes.NoCaptureLocal, 1000))
        {
            int index = Int32.Parse(pktView.SelectedItems[0].Text);
            Packet tmpPacket = buffer.ElementAt(index);
            communicator.SendPacket(tmpPacket);
        }
    }

    private void Receiving()
    {
        int c = int.Parse(packetcount.Text);

        using (PacketCommunicator communicator = selectedDevice.Open(65536,
         PacketDeviceOpenAttributes.NoCaptureRemote | PacketDeviceOpenAttributes.Promiscuous, 1000))
        {
            communicator.ReceivePackets(c, PacketHandler);
        }
    }
    private void button1_Click(object sender, EventArgs e)
    {
        thrReceive = new Thread(Receiving);
        thrReceive.Start();
    }

    private void buttonSend_Click(object sender, EventArgs e)
    {
        thrSend = new Thread(Sending);
        thrSend.Start();

    }

    private void pktView_SelectedIndexChanged(object sender, EventArgs e)
    {
        try
        {
            int index = Int32.Parse(pktView.SelectedItems[0].Text);
            Packet tmpPacket = buffer.ElementAt(index);
            textPacket.ResetText();
            textPacket.AppendText(tmpPacket.Ethernet.ToHexadecimalString());
        }
        catch (Exception E)
        {
            Console.WriteLine(E.ToString());
        }
    }

    private void buttonClear_Click(object sender, EventArgs e)
    {
        pktView.Items.Clear();
        buffer.Clear();
        pkt_cnt = 0;

    }
} }

回答1:

You seem to be using different PacketCommunicators, one for sending and one for receiving.

The documentation for NoCaptureRemote states "Defines if the local adapter will capture its own generated traffic.".

Since you're using two different communicators, the receiving communicator captures the sending communicator.

来源：https://stackoverflow.com/questions/39935404/c-sharp-pcap-net-communication