Network security starts from（  1  ）any user, most likely a username and a password. Once authenticated, a stateful firewall enforces （  2  ）such as what services are allowed to be accessed by network users. Though effective to prevent unauthorized access, this component fails to check potentially harm contents such as computer worms being transmitted over the network. An intrusion prevention system (IPS)helps detect and prevent such malware. （  3  ）also monitors suspicious network affic for contents, volume and anomalies to protect the network from attacks such as denial of service. Communication between two hosts using the network could be encrypted to maintain privacy. Individual events occurring on the network could be tracked for audit purposes and for a later high level analysis.  
（  4  ）, essentially decoy network-accessible resources, could be deployed in a network as surveillance and early-warning tools. Techniques used by the attackers that attempt to compromise these decoy resources are studied during and after an attack to keep an eye on new exploitation techniques. Such analysis could be used to further tighten security of the actual network （  5  ）by the honeypot. 
（1）A. authenticating   
B. Proofreading   
C. checking   
D. detecting     
（2）A. Control Strategy   
B. access permission   
C. access policies  
D. security strategy   
（3）A. lPS          
B.IDS           
C. P2DR     
D. P2DR2   
（4）A. Botnet          
B. Honeypots   
C. Phishing   
D. Demilitarized zone   
（5）A. being destroyed   
B. being attacked       
C. being damaged   
D. being protected