Hugo wrote: > -> IP > -> UDP > -> No endpoint found, return "Port not reachable" > -> IP sends ICMP Port not reachable. > > Axel may have a different view on this. Not really :-) But in addition to that, I think we should have a register_error_handler() function in the stack that the ICMP module would use. Then, IPv4 would just forward the error to the error module. On the other side, the ICMP module would need a way to report an error to a protocol as well. Bye, Axel.