Answer: Snort
Step-by-step explanation:Snort is a system which provides the service of the prevention of the intrusion. This system works as the open source for provision of the logging of packets and traffic analysis.
The functions in the snort are analysis of the protocol, content matching , searching etc. The main purpose of it is for the detection of the attack like stealth port ,CGI attacks etc.Other options are incorrect because they don't provides attack detection service.Thus the correct option is snort.