I have two sensors which broadcast their data using UDP. I configured them to use different ports.

If I connect only one sensor, I receive the packets using nc -ul port without any trouble.

If I connect both sensors, I get no packets via netcat from any of the sensors. However, the packets are properly detected by wireshark.


I just found out that it works correctly on another PC (same OS Ubuntu 16, a fresh installation). Anybody has an idea how to check what causes the problem on the first PC?

  • Can you capture a packet with tcpdump or wireshark and see what actual destination and source MAC and IP addresses the sensors are using? Is this all on wired Ethernet or is there any Wi-Fi involved? – Spiff Oct 9 '19 at 15:05
  • Guess: You have another process hanging around that listens on the port, because you don't killed a previous nc properly. – dirkt Oct 10 '19 at 9:14
  • @Spiff all wired Ethernet, tcpdump captures the packets. I think I discovered what is the problem. The sensors generate quite a lot of data and the bandwidth of my network is too low to handle it. – miloszmaki Oct 14 '19 at 10:41

Problem solved. The bandwidth of my network was to low to handle big amounts of data generated by multiple sensors.

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