I have confused about UDP port reservation by using C++ function. I'm new for network programming.
I have been tring to reserve UDP ports for my own experiment.
My target is to reserve around 500 ports for my application.
I followed this guidance here.
It is Microsoft document for blocking UDP port (from Dodcument said).
It is CreatePersistentUdpPortReservation function on C++.
As for my understanding, CreatePersistentUdpPortReservation function contacts with SIO_ACQUIRE_PORT_RESERVATION function to negotially reserve a port at runtime.
Hence, If I call CreatePersistentUdpPortReservation function to reserve approx. 5000 ports. For example, 60000-64999 (5000) ports. Then, any services will be theoretically not able to use one of them. They will be only use other avaialable ports (For example, 56000).
To check the result of the port reservation is completed, I captured DNS traffic in the machine, which I did the port reservation function, by Wireshark. I found that one port of 60000-64999 is applied for some service in the local machine from the capture result. So, that means CreatePersistentUdpPortReservation does not work? or I did a wrong?
I tried to find a reason to explain this problem. I re-checked many times about the function calling. It always returned 0 errorcode that means the function is worked completely. But why one of range UDP ports that I reserved is still used for other service after I did the ports reservation. Because this function did not reserve UDP port at first or the reservation time is expired ?
I am not sure about reservation time for reserving one UDP port for this function.
Also, anyone has any new idea on how to check the status of the UDP port for testing this function? Not only Wireshark, I tried network scanner to scan the reserved UDP ports, after calling the ports reservation function. The result said the reserved port is the open state.
