What are the different categories of IDS?
There exist (2) two different types of Intrusion Detection Systems. The first category includes Network Intrusion Detection Systems, or NIDS. With this type of IDS solution, packets are analyzed off the network medium on which hosts are connected. NIDS are used to detect anomalous activities that are designed to slip past firewalls. Host Intrusion Detection Systems, or HIDS, examines the activity occurring on that individual computer system. An example of this would be the detection of an application making a malicious SYSCALL to the Operating Systems kernel.
