answer all below questions in 2 or 3 lines each

11.1 List and briefly define three classes of intruders.
11.2 What are two common techniques used to protect a password file?
11.3 What are three benefits that can be provided by an intrusion detection system?
11.4 What is the difference between statistical anomaly detection and rule-based intrusion detection?
11.5 What metrics are useful for profile-based intrusion detection?
11.6 What is the difference between rule-based anomaly detection and rule-based penetration identification?
11.7 What is a honeypot?
11.8 What is a salt in the context of UNIX password management?
11.9 List and briefly define four techniques used to avoid guessable passwords.