T 5.50 Abuse of the ICMP Protocol

As a protocol of the transport level, the Internet Control Message Protocol (ICMP) has to transport error and diagnostic information. It may be abused in several ways. On the one hand, the routing tables of a computer may be changed by way of Redirect packets and undesirable routes may be configured. On the other hand an invader may smuggle falsified Destination Unreachable packets into the connection so that the existing connection is interrupted and the availability of the network connection is no longer given.