Signature and Anomaly-based IDS

This video explains what an intrusion detection system (IDS) does in general terms. You will learn about two common techniques used by IDS to identify threats. What are these two common techniques and how do they detect system attacks? Where can IDS software be placed on a small network, and where can it be placed to keep from slowing down systems on the network? What is a popular opensource IDS software? What are the two types of protection offered by IDS software?