A program on machine X attempts to open a UDP connection to port 5376 on a machine Y, and a TCP connection to port 8632 on machine Z. However, there are no applications listening at the corresponding ports on Y and Z. An ICMP Port Unreachable error will be generated by ?
ICMP Port unreachable is a code 3 within type 3
3.3.Port Unreachable - generated if the designated transport protocol (e.g., UDP) is unable to demultiplex the datagram in the transport layer of the final destination but has no protocol mechanism to inform the sender
I read many online content of related this topic. But ,still , I'm in doubt , I can't say anything for TCP with correct reference . I conclude that it should be for both TCP and UDP , Since ICMP is a network layer protocol , and it is not related with transport layer protocols(i.e. TCP , UDP) . Hence , it don't bother about TCP or UDP , it returns error for both TCP and UDP . I need verification .