Intrusion-detection systems are used to detect unusual activity in a network of computer systems, to identify that activity as unfriendly or unauthorized and to enable a response to that intrusion.

• 入侵探测系统是用来探测计算机系统网络上不寻常的活动，以识别出此活动是不友好的或者未经授权的，以便能够对此入侵作出响应。