You can configure an intrusion detection program to send e-mail to a system administrator to alert them to suspicious events and provide suggestions as to what action to take.
An intrusion detection program should take suspicious events into account as well as network problems that occur for other reasons such as hardware or configuration problems. For example, ICMP redirect messages might indicate that a router is not fully configured yet. Sometimes routers are slow to figure out which router in a network is the best route to a destination.