本文出自Simmy的个人blog：西米在线 http://simmyonline.com/archives/66.html

A network analyzer is used for:

■ Converting the binary data in packets to readable format
■ Troubleshooting problems on the network
■ Analyzing the performance of a network to discover bottlenecks
■ Network intrusion detection
■ Logging network traffic for forensics and evidence
■ Analyzing the operations of applications
■ Discovering faulty network cards
■ Discovering the origin of virus outbreaks or Denial of Service (DoS)
attacks
■ Detecting spyware
■ Network programming to debug in the development stage
■ Detecting a compromised computer
■ Validating compliance with company policy
■ As an educational resource when learning about protocols
■ Reverse-engineering protocols to write clients and supporting programs
Intruders use sniffers on networks for:
■ Capturing cleartext usernames and passwords
■ Discovering the usage patterns of the users on a network
■ Compromising proprietary information
■ Capturing and replaying Voice over IP (VoIP) telephone conversations
■ Mapping the layout of a network
■ Passive OS fingerprinting