Thanks, I managed to develop solution for UDP packets. Now I experience other issue with transparent proxy. Once I enable transparent proxy it is not possible to ping any server, I get "Protocol wrong type for socket". You can find details in attachment. Does transparent proxy block all other network traffic except TCP and UDP? It shouldn't be related with my proxy implementation because ping doesn't work even if I create dummy proxy that just returns "false" in handleNewFlow callback and causes the flow to proceed to communicate directly with the flow's ultimate destination.