Same package appears twice in wireshark


I work with FreeRTOS Windows port to develop my library. I just realize that, Wireshark makes it look like the same ethernet packet was sent twice. I’m sure pcap_sendpacket function is called only once. I’m pretty sure the same package wasn’t sent twice because I have a udp send receive test with counter. Is it known issue or am I missing something?

I wish you good work.

can you share the pcap for us to inspect? Filtered would be fine. (1.0 KB)

Only required packages are shown. 25th byte of the data(total is 28 byte) is counter.

I believe that it is an issue with the pcap_sendpacket and use of Wireshark. I think since Wireshark uses the pcap interface to read the incoming packets, the use of pcap_sendpacket leads to Wireshark seeing suplicate packets.

But FreeRTOS+TCP doesn’t actually send the packet twice (as you already mentioned :slightly_smiling_face:)
Don’t worry, it is not a bug in your code. Do note that windows simulator port should not be used for production level code - it is to be used for learning and debugging purpose only :slightly_smiling_face:


Hello again,

Thank you for reply. Because i used old version of wireshark before both winpcap and npcap are installed on my PC. I removed winpcap from my PC and changed Freertos WinPort pcap library with npcap. The app seems to be working fine but duplicate packets still appear in Wireshark.

I wish you good work.


I removed npcap and reinstall wireshark 3.4.0 with winpcap 4.1.3 and duplicate package problem is solved.

Thank you.