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Since the number of server providing the facilities for users is usually more than one, remote user authentication schemes used for multi-server architectures, rather than single server circumstance, is considered. In 2007, Liao and Wang proposed a “secure dynamic ID based remote user authentication scheme for multi-server environment” that uses dynamic ID instead of static ID to achieve user's anonymity for verifying the legitimacy of a remote login user. In this paper, we analyze their protocol and demonstrate that it cannot achieve true anonymity and has some other weaknesses. We further propose the improvements to avoid those security problems. Besides user privacy, the key features of our scheme are including no verification table, freely chosen password, mutual authentication, low computation and communication cost, single registration, session key agreement, access control, and being secure against the related attacks.