Fingerprinting attack is a major threat to enterprise networks since it enables adversaries to easily figure out the operating system of target hosts. Due to the fact that OS fingerprint is a key indicator of a majority of vulnerabilities, it is critical to obfuscate the fingerprint. However, it is a challenge to achieve this goal with end-host transparency, lossless network functionality, and acceptable performance penalty. We propose a novel scheme named MOFA(Moving OS Fingerprint Adaptively), which makes full use of the packets monitoring and controlling capability of SDN switches to provide a convenient moving target defense service for fingerprint attacks. MOFA dynamically shifts various attack surface of fingerprinting with strategies determined by the possibility of undergoing fingerprint attacks. The result of experiments indicates that MOFA is capable of disrupting the fingerprinting attack with little burdens on network performance.