Adding security to remote file access is merely a matter of taking the various secure requirements, and the technology presented in chapter 4, and applying them to the particular file access protocol in hand. One existing example of this is the Multi-level secure version of the Network File System presented earlier: This includes discretionary access control (DAC), subject and object security labeling, mandatory access control (MAC), authentication, auditing, and documentation. NFS provides authentication in a range of ways, and by extending the credentials required, one can provide multiple levels of access. For example, MLS adds: