The Network File System (NFS) and the Remote File Sharing (RFS) service are distributed file systems which use a client/server model to allow computers to share files over the network. NFS and RFS allow users to access, read, and change the contents of files stored on servers without having to log into the server or supply a password. This feature results in several security problems.
In order to share files using a distributed file system, directories of files must first be exported by the server. Once the client has mounted the exported files, users may access these files as though the files were stored locally. There are many threats associated with using distributed file systems, especially if no precautions are taken when exporting directories from the server.