Rule:--Sid:395--Summary:This event is generated when an ICMP Destination Network Unknown datagram is detected on the network.  Gateway devices normally generate these ICMP messages when the destination network is unreachable.--Impact:This ICMP message will be generated when the destination network specified in the datagram is unreachable.--Detailed Information: This rule generates informational events about the network.  Large numbers of these messages on the network could indication routing problems or faulty routingdevices.--Attack Scenarios:None Known--Ease of Attack:Numerous tools and scripts can generate these types of ICMP datagrams.--False Positives:None Known--False Negatives:None Known--Corrective Action:This rule detects informational network information, no correct action is necessary.--Contributors:Original Rule writer unknownSourcefire Research TeamMatthew Watchinski (matt.watchinski@sourcefire.com)--Additional References:None--