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

A circuit-level proxy operates at the session layer and handles or silently drops connections rather than generating ICMP administratively prohibited messages.

Honeypots and jails are designed to simulate open services and engage attackers, not to emit ICMP administrative prohibition responses.

Malformed packets from scanning software would cause parsing or checksum errors at the destination, not trigger an ICMP administratively prohibited response from a network device.

ICMP Type 3 Code 13 is generated specifically by routers and stateless packet-filtering devices when an ACL or firewall ruleset drops a packet due to an administrative policy, as defined in RFC 1812. Unlike a silent drop, this response leaks the presence of a filtering device to the attacker. It distinguishes policy-based blocking from routing failures, giving the attacker actionable reconnaissance data.

An administratively prohibited ICMP message is a deliberate security-policy block indicator, not evidence of normal, unfiltered network operation.