SephStorm wrote: » I assume by vulnerability testing you mean vulnerability scanning, which would diferentiate from pen-testing, in that pen-testing involves exploiting vulnerabilities found during vulnerability scanning. As for IDS, an IDS signature will detect a known attack, such as a port scan or certain types of traffic, whereas behavior based IDS will detect changes from a baseline. i.e. if a system was only used for web traffic suddenly started sending email traffic, that would be a deviation from the baseline, and generate an alert. Yes, you are seeing abnormal behavior, however, the sig IDS is detecting BASED on the signature, not the behavior.