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New Post: Fix bad checksum packet

Brickner — Fri, 14 Jun 2013 13:53:24 GMT

I don't know why.
And yes, this is a good way to check it.

New Post: Fix bad checksum packet

gshhar — Sat, 08 Jun 2013 12:02:38 GMT

So why this large packets has bad checkum ?

This is the way to check packet size ?

New Post: Fix bad checksum packet

Brickner — Sat, 08 Jun 2013 10:06:08 GMT

Usually Ethernet packet size don't exceed 1514 bytes (14 bytes for Ethernet header and 1500 for payload).

New Post: Fix bad checksum packet

gshhar — Sat, 08 Jun 2013 08:11:18 GMT

I checked now with another computer and it seems that it works fine.
can you show me how to check and see this large packets ?
because this packets comes from VMware machine and maybe i can change the packet size, what is the packet limit that network card could send ?

New Post: Fix bad checksum packet

Brickner — Sat, 08 Jun 2013 07:02:57 GMT

Have you seen such large packets go out from these machines?

New Post: Fix bad checksum packet

gshhar — Fri, 07 Jun 2013 14:30:10 GMT

NO because i have check it with several machines and on all those machine the result was the same.

New Post: Fix bad checksum packet

Brickner — Fri, 07 Jun 2013 11:47:53 GMT

Packet length does seems suspicious large.

It also seems that the original packets with the bad checksum are also very large.
It's possible that you can't send such large packets with your device.

Boaz.

New Post: Fix bad checksum packet

gshhar — Sat, 01 Jun 2013 14:44:53 GMT

After change to SendPacket:

nvalidOperationException was caught
InnerException: null
Message: Failed writing to device. Packet length: 2974. WinPcap Error: send error: PacketSendPacket failed
StackTrace: at PcapDotNet.Core.PacketCommunicator.SendPacket(Packet packet)
at packetPlayer.Pcap.sendBuffer(PacketDevice packetDevice) in d:\Drivers\projects\PacketPlayer\PacketPlayer\classes\Pcap.cs:line 288

i would say that the packet length is the reason ?

this is my code (moved some irrelevant code):

            OfflinePacketDevice selectedInputDevice = new OfflinePacketDevice("MyFile");
            PacketDevice selectedOutputDevice; //my interface 

            using (PacketCommunicator inputCommunicator = selectedInputDevice.Open(65536, PacketDeviceOpenAttributes.Promiscuous, 1000))
            {
                using (PacketCommunicator mOutputCommunicator = selectedOutputDevice.Open(100, PacketDeviceOpenAttributes.Promiscuous, 1000))
                {
                    Packet packet;

                    while (inputCommunicator.ReceivePacket(out packet) == PacketCommunicatorReceiveResult.Ok) //fill the buffer with the packets from the file
                    {
                        using (PacketSendBuffer mSendBuffer = new PacketSendBuffer((uint)packet.Length * 4))
                        {
                            try
                            {
                                mOutputCommunicator.SendPacket(packet);
                            }
                            catch (Exception ex)
                            {

                            }
                        }
                    }
                }
            }

New Post: Fix bad checksum packet

Brickner — Sat, 01 Jun 2013 13:36:28 GMT

According to the call stack, it seems you're using Transmit() and not SendPacket().
Please change it to SendPacket() so it's easier to debug.
Also, I'll need to take a look at the code you run and not just the packet creation method.

New Post: Fix bad checksum packet

gshhar — Sat, 01 Jun 2013 06:51:59 GMT

InvalidOperationException was caught

InnerException: null

Message: Failed transmiting packets from queue. WinPcap Error: Error opening adapter: Error opening adapter: Error opening adapter: Error

StackTrace: at PcapDotNet.Core.PacketSendBuffer.Transmit(pcap* pcapDescriptor, Boolean isSync)
at PcapDotNet.Core.LivePacketCommunicator.Transmit(PacketSendBuffer sendBuffer, Boolean isSync)
at packetPlayer.Pcap.sendBuffer(PacketDevice packetDevice) in d:\Drivers\projects\MyApplication\classes\Pcap.cs:line 287

New Post: Fix bad checksum packet

Brickner — Sat, 01 Jun 2013 06:34:33 GMT

Can you give the full exception description with the full call stack when you use OutputCommunicator?

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sanz86 — Fri, 31 May 2013 12:19:38 GMT

Thans Brickner for your help.

New Post: Fix bad checksum packet

gshhar — Fri, 31 May 2013 11:32:40 GMT

Any solution ?

New Post: Fix bad checksum packet

gshhar — Fri, 31 May 2013 11:01:13 GMT

Still the same error

New Post: Fix bad checksum packet

Brickner — Fri, 31 May 2013 10:54:18 GMT

Using Transmit() can be a bit tricky.
Can you first try and use the simple SendPacket() method to see if this works?

New Post: Fix bad checksum packet

gshhar — Fri, 31 May 2013 10:36:15 GMT

That is what i did now.
this link: http://www.sendspace.com/file/mkpf3h contain 1 packets that successfully save after the fix (only save without send)

when try to send this packet with the bad checksum and after this packet pass my fixBadChecksum function - i get an exception in OutputCommunicator.Transmit

New Post: Fix bad checksum packet

Brickner — Fri, 31 May 2013 10:25:26 GMT

I don't understand, do you get an exception? How is this stack trace helpful?

I suggest you just try to save a single packet and not transmit it and see how it looks like in a pcap file.

New Post: Fix bad checksum packet

gshhar — Fri, 31 May 2013 10:25:09 GMT

This is 1 packet after the fix and save as you ask: http://www.sendspace.com/file/mkpf3h

New Post: Fix bad checksum packet

gshhar — Fri, 31 May 2013 10:23:51 GMT

Failed transmiting packets from queue. WinPcap Error: Error opening adapter: Error opening adapter: Error opening adapter: Error

Ok this is the StackTrace from OutputCommunicator.Transmit(mSendBuffer, _isBurst);: at PcapDotNet.Core.PacketSendBuffer.Transmit(pcap* pcapDescriptor, Boolean isSync)
at PcapDotNet.Core.LivePacketCommunicator.Transmit(PacketSendBuffer sendBuffer, Boolean isSync)
at packetPlayer.Pcap.playCapture(PacketDevice packetDevice) in d:\Drivers\PacketPlayer__\MyApplication\classes\Pcap.cs:line 275

New Post: Fix bad checksum packet

Brickner — Fri, 31 May 2013 10:19:45 GMT

Can you show me how the packets look like if you save them to file instead of trying to transmit them?