Destination unreachable administratively prohibited messages can inform the hacker to what?

A.
That a circuit level proxy has been installed and is filtering traffic

B.
That his/her scans are being blocked by a honeypot or jail

C.
That the packets are being malformed by the scanning software

D.
That a router or other packet-filtering device is blocking traffic

E.
That the network is functioning normally

Explanation:
Destination unreachable administratively prohibited messages are a good way to discover that a router or other low-level packet device is filtering traffic. Analysis of the ICMP message will reveal the IP address of the blocking device and the filtered port. This further adds the to the network map and information being discovered about the network and hosts.