Worth noting, however, is that many IPS sensors use signature-based detection, meaning that attacks are added to a database as they are discovered.

但是，值得牢记的是，许多IPS嗅探器使用基于特征码的检测方法，这意味着当攻击被发现的时候才能被加入到数据库中。

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Many of current IDSes implement only signature-based intrusion detection which gives them less false positive but with a unbearable false negative.

当前大多数IDS系统仅采用基于特征的检测以减少误报，然而这会造成不可忍受的漏报问题。

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For intrusion pattern based signature detection, an improved quick multi-pattern matching algorithm is adopted, which can search for multiple patterns by scanning the packet once.

对基于入侵模式的特征，采用了一种改进的快速多模式匹配算法可以一次在包的负载中查找多个入侵模式。

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These techniques help criminals evade signature-based detection and stay on the network.

FORBES: Is anyone safe? Spate of incidents raises security concerns

In general, the signature-based security products used to defend enterprise networks, such as firewalls, anti-virus products and intrusion detection systems are increasingly blind to modern attack methods, which are increasingly embedded into application data or designed to self-mutate in order to evade detection.

FORBES: Cyberwar Or Not Cyberwar? And Why That Is The Question