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Honolulu College Computers Electronic and Networking Technology UNIX System Administration page 1 Curriculum version 2.0
Network File System NFS NFS was developed by Sun Microsystems and is now incorporated into the operating systems of many other vendors. NFS is a method of sharing directories from one computer to another. NFS is a client server application. The latest version of the NFS service Version 3 is based on TCP/IP Protocols. The machine that has a locally attached disk with files that are to be shared must run the NFS server. The machine that needs to access the shared files must incorporate NFS client software. Solaris and many other UNIX systems install both client and server NFS services as part of a standard installation. Setting up the NFS Server Directories can be shared with the command share. example: share -F ufs o ro d Man Pages /usr/man This command would share the directory /usr/man as a read only file system with the description "Man Pages". Directories shared with the share command would not automatically be shared again when the computer is rebooted. File systems or directories that are to be shared can also be entered into the /etc/dfs/dfstab file. This file lists the directories to be shared as well as information on which clients may have access to them and the permissions that are granted. When directories to be shared are listed in the /etc/dfs/dfstab file they are automatically shared when the machine is rebooted. The startup scripts read the /etc/dfs/dfstab file and share any listed directories or file sytems. Just using the share command or editing the /etc/dfs/dfstab file may not result in the directory being shared. The NFS server program must also be running. It does not start at boot time unless there is at least one valid entry in the /etc/dfs/dfstab file. The script that starts the nfs server program is /etc/init.d/nfs.server it is linked to an S script in the rc3.d directory so that NFS services are started when the system enters run level 3. The script checks the /etc/dfs/dfstab file before starting the server at boot time. To manually start the nfs server use the command /etc/init.d/nfs.server start. It is always recommended that the script be run with the stop parameter first and then the start. This assures you that the server will not be running twice and that all the associated daemons such as lockd and statd and mountd are also running correctly. /etc/init.d/nfs.server stop /etc/init.d/nfs.server start 928bd2a1e06074a2e6d3e04fad72d04d298f5488.doc 06/15/09 Page 1 of 4
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Honolulu Community College Computers Electronic and Networking Technology UNIX System Administration page 2 Curriculum version 2.0
After adding at least one entry in the /etc/dfs/dfstab file and starting the nfs server it is easier to share more directories. Either share them directly with the share command or add them to the /etc/dfs/dfstab file and use the command shareall The shareall command reads the /etc/dfs/dfstab file and mounts every entry. It is a good way to make sure that the dfstab does not have any errors. To unshare a file system or directory you can use the unshare command. unshare /usr/man The syntax for the /etc/dfs/dfstab file is: share -F <fs type> -o <options> -d < description> <pathname of dir to share>
The F is followed by the file system type, usually NFS The is o followed by many possible options The d is followed by an optional descrtiption The pathname is the absolute pathname to the directory to be shared. The directory to be shared must be locally mounted. You cannot share a directory that has already been mounted from another server. Share -o options rw read / write Indicates that systems that mount the shared directory can read and write to the directory and subdirectories.
rw=client-host1:client-host2 read write only to listed hosts. ro read only
ro=client-hosts anon=<uid> sets uid to be the effective user ID of unknown users. By default unknown users are give the effective user id nobody. if anon=-1 then unauthenticated users are denied access.
928bd2a1e06074a2e6d3e04fad72d04d298f5488.doc 06/15/09
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Project nosub
Honolulu Community College Computers Electronic and Networking Technology UNIX System Administration page 3 Curriculum version 2.0 prevents clients from mounting subdirectories. They must mount the entire shared system.
nosuid server system ignores any attempt to set suid and guid bits on files. root=client-host The dfstab example /etc/dfs/dfstab # Place share commands here for automatic sharing upon entering run state 3 # # share -F nfs /export share -F nfs -o ro -d Man Pages /usr/man share -F nfs -o rw=lulu,bart,dilbert root=dilbert -d Home /local/home The /etc/dfs/dfstab shown above would share 3 directories. The /export directory would be shared with default options and no description. The /usr/man directory would be available for any system on the network to mount, but it would be mounted read only. None of the systems that mounted the file system would be able to modify, add or delete any files in /usr/man. The /local/home directory would be available to only to the hosts lulu bart and gecko. They would be able to mount the directories as Read and Write. Only dilbert would be able to access the shared directory as root. Clients mount a shared directory similar to mounting local directories except the shared directory is ...