Intrusion Detection Systems

The best method to allow you to make certain your wireless network is
protected against intruders is to implement and carefully monitor an
intrusion detection system (IDS), so that unauthorized users are caught trying to access your network. If a hacker does access your network, the
IDS will send an emergency alert to the administrator of your network
with the hope that he will catch the attack in progress, find the open
vulnerability, and prevent the hacker from accessing the network in the
future.

When dealing with a wireless network, the intrusion detection system
you choose can be a host-based intrusion detection system (HIDS) or a
network-based intrusion detection system (NIDS).