I am developing a client/server app on redhat 8 that uses UDP to send and receive some data (the redhat 8 computer is the client). I need to use UDP because TCP is too slow for my current needs and the TCP version works already anyway. I am testing over a crossover cable point to point and what occasionally happens is that tcpdump indicates that it received a packet destined for my port, but the application never receives it in the recvfrom call, although it does receive the next packet. What would cause the stack to not route the packet to the application? Any ideas what I could do to fix this?