Intrusion Detection Systems are important tools for system administrators to protect their network. However they find more and more difficulties with high speed networks. To enhance their capacity and deal with evasion techniques, frequently used by hackers, we have introduced a new method to filter the network traffic. The detection method, while being stateful, processes each packet as soon as it is received. We have employed this strategy after a new classification of detection rules. Then, we have used efficient multisearch methods and suitable datastructure for signatures. The method has been successfully implemented as an extension of the Intrusion Detection System "Snort". || Les systèmes de détection d'intrusions sont devenus indispensables pour les administrateurs afin de protéger leurs réseaux. Cependant, ces outils présentent des lacunes pour traiter le haut débit et mener une analyse précise du contenu des paquets. Nous p