Cisco IDS-4230-FE - Intrusion Detection Sys Fast Ethernet Sensor Installation And Configuration Manual page 31

Chapter 1 Introducing the Sensor
Appliances
Figure 1-2 Appliance in Front of a Firewall
Hostile
network
ISP router
Outermost router
Monitoring interface
IDS Appliance
Firewall
Protected network Control interface
Management host
Placing an appliance behind a firewall allows it to monitor internal traffic, but it
cannot monitor any policy violations that the firewall rejects (see Figure 1-3 on
page 1-8).
Cisco Intrusion Detection System Appliance and Module Installation and Configuration Guide Version 4.1
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