Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 13Network File SharingIN THIS CHAPTER. Network File System. Samba File SharingIn an enterprise computing environment, it is common toshare files between computers or allow several users toaccess the same set of files on a central server and have allchanges be visible to all users immediately. In a pure UNIXenvironment, including those consisting solely of Red HatEnterprise Linux systems, this can be achieved via NetworkFile System (NFS). If sharing files between Red HatEnterprise Linux and Microsoft Windows systems isdesired, Samba can be used to achieve connectivity.Network File SystemNFS, or Network File System, is a server-client protocol forsharing files between computers on a common network. Itis available on a variety of UNIX-based operating systems,not just Linux. The server and client do not have to use thesame operating system. The client system just needs to berunning an NFS client compatible with the NFS server.The NFS server exports one or more directories to the clientsystems, and the client systems mount one or more of theshared directories to local directories called mount points. Afterthe share is mounted, all I/O operations are written back tothe server, and all clients notice the change as if it occurredon the local filesystem. A manual refresh is not neededbecause the client accesses the remote filesystem as if it werelocal. Access is granted or restricted by client IP addresses.One advantage of NFS is that the client mounts the remotefilesystem to a directory thus allowing users to access it inthe same method used to access local files. Furthermore,because access is granted by IP address, a username andpassword are not required. However, there are security risksto consider because the NFS server knows nothing aboutthe users on the client system. The files from the NFSserver retain their file permissions, user ID, and group IDwhen mounted. If the client uses a different set of user andgroup IDs, file ownership will change.