GEN:SID 1:402
Message ICMP Destination Unreachable Port Unreachable
Summary An ICMP Port Unreachable was detected.
Impact An ICMP Port Unreachable is not an attack, but may indicate that the source
of the packet was the target of a scan or other malicious activity.
Detailed Information An ICMP Port Unreachable (ICMP type 3 code 3) indicates that someone or
something tried to connect to a port on a system that was not available
(i.e., no service was running on that port).
This is analagous to RST packets in TCP.  Since UDP does not have an
equivalent, it relies upon ICMP Port Unreachable for this.  This often
indicates someone was scanning for UDP services.
Affected Systems  
Attack Scenarios  
Ease of Attack  
Corrective Action Examine the activity of the recipient of this packet to see if the
recipient was responsible for scanning or other behavior.
Additional References