In my understanding, if you have a UDP socket client that is bound to a particular port, then a second UDP client on the same machine can't bind to the same port.

If this is the case, then how can a packet sniffing program like Wireshark run on the same machine you have a UDP client without issues?

1 Answer 1


Packet sniffing applications tap into the lower layers of the network stack, not at the top like your UDP-using applications that connect to UDP at the top of the network stack.

  • Are you saying that the packet sniffing applications work at the network/routing layer?
    – Fred
    Dec 13, 2018 at 22:04
  • Even lower than that. Most can capture the Data-Link frames.
    – Ron Maupin
    Dec 13, 2018 at 22:05
  • 1
    @Fred Usually the packet capturing happens right on top of the NIC, ie. between layer 2 and 3.
    – Zac67
    Dec 13, 2018 at 22:11

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