The wide use of Wireless Local Area Network (WLAN) has required the increase of Wireless Intrusion Detection System (WIDS) technology to focus on protecting the wired and wireless infrastructures from internal and external attacks. This book explores the different alternatives to design and implement an Embedded Intrusion Detection System (IDS) in order to protect a multi services wireless network. The targeted IDS must have a small size in order to be integrated in different wireless devices, low cost in order to be placed in many places of network, and has good performance to cover the data rate of the WLAN. All these attributes are achieved by Network Processor and System on Chip(SOC) Technologies. In order to build an efficient IDS, the time for checking the packet and searching signatures inside the payload must be small. So, an efficient pattern searching algorithms must be used in order to constrain the best one that is suitable for Network processor platform. The Experimental results obtained from this work indicate that the proposed IDS can be worked efficiently at IEEE 802.11x WLAN network which provides different services to its clients.