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Nmap Project's Windows packet capture and transmission library
https://npcap.com
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Sending many custom frames with npcap on an interface cause corruption in the other frames sent from the interface. #242

Open axel-tessore opened 4 years ago

axel-tessore commented 4 years ago

We are using the npcap library to send EtherCAT frames to an EtherCAT network (a packet every few milliseconds). The windows protocols are still active, we cannot deativate them. The EtherCAT network is tolerant to non EtherCAT ethernet frames, but it happen that, when pcap is in use to send the EtherCAT frames, some Windows frames (ie. DHCP request) exit corrupted, and alters the error counters of the EtherCAT slaves. There isn't any problem on the frames sent by the npcap library.

dmiller-nmap commented 3 years ago

Thanks for the report. Can you provide more information about your Npcap installation and configured adapters? DiagReport works well for this.

Also, do you have a packet capture of the corrupted frames available? It would be very helpful to know exactly how the frames are corrupted.

axel-tessore commented 3 years ago

Good morning, attached the DiagReport result DiagReport-20201016-145418.txt

I cannot have a trace of the corrupted packet: our customer detected them with their capture device, signaling there are CRC errors.

I can detect them since my EtherCAT slaves counter of malformed packets increase. Note that a valid EtherNET frame, not EtherCAT, is dropped by the slaves without increasing counters, the counters are incremented only if a non regular ethernet frame is corrected.