Abstract-By studying the Kerberos authentication scheme, an improved authentication scheme is raised, which is based on Dynamic Password Method. In the improved scheme, user's password can be effectively protected, and the authentication is double between users and severs. Also, the scheme can resist jacking connection attack. The improved scheme is more secure and more practical than the original one.

Network not only brings people convenience, but also becomes a hotbed for breeding crime. And it not only brings people efficiency, but also opens a new criminal platform for the computer network criminals. This paper analyzes the performance form and main features of computer networks crime and proposes several control measures based on their form and features.