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npcap stops EtherNet/IP responses #1424

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MusaMan opened this Issue Jan 3, 2019 · 2 comments

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@MusaMan
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MusaMan commented Jan 3, 2019

Hello

I am using Wireshark with npcap on Windows 7 to develop an EtherNet/IP client application. Setup is as follows: My development PC -> VPN into the office -> EtherNet/IP Device connected to network. I have been using Npcap 0.99-r8 and Npcap 0.99-r7 - the issue is the same.

Test scenario:

  • Start test application, send any EtherNet/IP request packet (e.g. List Identity, using UDP unicast)
    => Response is successfully received
  • Start WireShark witn NPcap driver, select appropriate NdisWan Adapter.
  • Send any EtherNet/IP request packet (e.g. List Identity, using UDP unicast)
    => Request packet can be seen in Wireshark, but no response.
    => Subsequent request packets can be seen in Wireshark, but no response.
  • Stop logging or Exit WireShark
  • Send any EtherNet/IP request packet (e.g. List Identity, using UDP unicast)
    => Response is successfully received

I use my own EtherNet/IP client software or the free Molex EtherNet/IP tool, which is great for showing this issue. Download: https://www.molex.com/mx_upload/superfamily/iccc/EtherNet_IPTool.html
Usage: Start tool, stay on first tab (List Identity), Message Type 'Unicast', enter IP address of target device, press 'Send List Identity Request on UDP'. If successful, 'Station' (device) will show up in the frame to the right, otherwise not.

Thanks.

@dmiller-nmap

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dmiller-nmap commented Jan 14, 2019

Thanks for this bug report. Can you clarify whether:

  1. the responses are still received (as evidenced by the EtherNet/IP software working correctly) but simply not displayed by Wireshark, or
  2. the packets appear to be blocked while the packet capture is running.

Additionally, please provide output from DiagReport to help us diagnose the problem.

@MusaMan

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MusaMan commented Jan 17, 2019

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