How to Configure NFS(Network File System) in Linux

To Setup NFS (Network File System)

Network File System is the most commonly used network services. It is based on the Remote procedure call. It allows the client to mount automatically on remote file systems. It provides transparent access to it as if the file system is local. Setup NFS (Network File System) on RHEL/CentOS/Fedora and Debian/Ubuntu is explained in this article.

Uses of NFS

• To share out data on a central server
• Can be secured with Kerberos and Firewalls.
• Newer version of NFS supports pseudo, acl root mounts.
• No manual refresh needed for new files.
• USB storage devices can be used by other machines on the network.
• Users get their data irrespective of physical location.
• With the help of NFS we can configure centralized storage solutions.
• With NFS it is not necessary that both machines run on the same OS.
• It uses standard client/server architecture for file sharing between all *nix based machines.
• NFS permits local access to remote files.

Services of NFS

Its a V-launched service of the System. The NFS server package has three facilities, which are included in the nfs-utils and portmap packages.

• nfs translates remote file sharing requests into the local file system requests.
• Portmap maps calls from other machines to the correct RPC service (not required with NFSv4).
• rpc.mountd service is responsible for mounting and unmounting of file systems.

Files Necessary for the Configuration of NFS

/etc/exports : Its a major NFS, all exported files and directories configuration files are defined in this file at the NFS Server end.
/etc/sysconfig/nfs : NFS Configuration file to control on which port rpc and other services are listening.
/etc/fstab : For mounting an NFS directory on your computer over the reboots, we have to make an entry in /etc/fstab.

Setting up and Configuration of NFS Mounts on Linux Server

For setting up NFS mounts, we require at least two Unix/Linux machines.

NFS Client IP : 192.168.5.148
NFS Server IP : 192.168.5.147

To Install NFS Server

Install NFS Server by executing the following command in NFS server machine.

root@linuxhelp1:~# sudo apt install nfs-kernel-server

To Install NFS Client

Install NFS Client by executing the following command in NFS client machine.

root@linuxhelp:~# sudo apt-get install nfs-common

To Set Up the NFS Server

To Configure Export directory

To make our directory shareable in the network, make an entry in “ /etc/exports” and restart the services .

root@linuxhelp1:~# vim /etc/exports
# /etc/exports: the access control list for filesystems which may be exported
.
.
.
# /srv/nfs4/homes  gss/krb5i(rw,sync,no_subtree_check)
#
/home   192.168.5.148(rw,sync,no_root_squash)

Now, if you specify any particular IP then it will share the folder only with the specified client. If you mention " *" then it is an open access to everyone.

NFS Options

Various options that can be used in “ /etc/exports” file for file sharing are as follows.

no_root_squash is a phrase, which permits root to connect to the specified directory.
no_subtree_check is an option that prevents the subtree checking.
ro - provides read only permission. Client will be able to read only the shared files.
rw - Provides the client server to both read and write permission in the shared directory.
sync, which confirms requests to the shared directory after the changes have been committed.

Now restart the service.

root@linuxhelp1:~# sudo systemctl restart nfs-kernel-server.service

To Set Up the NFS Client

After the configuration of the NFS server, mount the partition or shared directory in the client server. Now we have to mount the directory in our server at the NFS client end, to access it locally. For that, find out that shares on the NFS Server or the remote server.

root@linuxhelp:~# showmount -e 192.168.5.147
Export list for 192.168.5.147:
/home 192.168.5.148

Before that I am going to show you the partitions that are mounted in the client system

root@linuxhelp:~# df -h
Filesystem           Size  Used Avail Use% Mounted on
udev                 476M     0  476M   0% /dev
tmpfs                 99M  5.5M   93M   6% /run
/dev/sda3             11G  4.1G  6.4G  39% /
tmpfs                493M  156K  492M   1% /dev/shm
tmpfs                5.0M  4.0K  5.0M   1% /run/lock
tmpfs                493M     0  493M   0% /sys/fs/cgroup
/dev/sda2            269M   53M  198M  22% /boot
cgmfs                100K     0  100K   0% /run/cgmanager/fs
tmpfs                 99M   48K   99M   1% /run/user/1000

Mount Shared NFS Directory

Use the following command, to mount the shared NFS directory temporarily.

root@linuxhelp:~# mount -t nfs 192.168.5.147:/home /mnt

Now verify it by using the following command.

root@linuxhelp:~# mount | grep nfs
192.168.5.147:/home on /mnt type nfs4 (rw,relatime,vers=4.0,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.5.148,local_lock=none,addr=192.168.5.147)

For mounting permanently an NFS directory on your computer over the reboots, make an entry in “ /etc/fstab“ .
After that I am going to show you the partitions that are mounted in the client system.

root@linuxhelp:~# df -h
Filesystem           Size  Used Avail Use% Mounted on
udev                 476M     0  476M   0% /dev
tmpfs                 99M  5.5M   93M   6% /run
/dev/sda3             11G  4.1G  6.4G  39% /
tmpfs                493M  156K  492M   1% /dev/shm
tmpfs                5.0M  4.0K  5.0M   1% /run/lock
tmpfs                493M     0  493M   0% /sys/fs/cgroup
/dev/sda2            269M   53M  198M  22% /boot
cgmfs                100K     0  100K   0% /run/cgmanager/fs
tmpfs                 99M   48K   99M   1% /run/user/1000
192.168.5.147:/home   11G  4.1G  6.4G  40% /mnt

root@linuxhelp:~# vim /etc/fstab
Insert the below new line :

# /etc/fstab: static file system information.
.
.
.
/dev/fd0        /media/floppy0  auto    rw,user,noauto,exec,utf8 0       0
192.168.5.147:/home     /mnt    nfs     defaults        0       0

To Test the Working of NFS Setup

By creating a test file on the server side, check whether it is available in nfs client side.

In nfsserver side

In the shared directory, Create a new text file called “ file1”

root@linuxhelp1:/home# touch file1

In nfsclient side

Since client have read write permission so edit the file in client side

root@linuxhelp:/mnt# ls
testmail  user1
root@linuxhelp:/mnt# ls
file1  testmail  user1
root@linuxhelp:/mnt# vim file1
hello

In Server Side

You can be able to view the modified file from the client side in the server.

root@linuxhelp1:/home# ls
file1  testmail  user1
root@linuxhelp1:/home# cat file1
hello

To Remove the NFS Mount

To unmount the shared directory from your server after the completion of file sharing, unmount that specific directory using the following command.

root@linuxhelp:~# umount /mnt

Look at the filesystem once again to verify.

root@linuxhelp:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            476M     0  476M   0% /dev
tmpfs            99M  5.5M   93M   6% /run
/dev/sda3        11G  4.1G  6.4G  39% /
tmpfs           493M  156K  492M   1% /dev/shm
tmpfs           5.0M  8.0K  5.0M   1% /run/lock
tmpfs           493M     0  493M   0% /sys/fs/cgroup
/dev/sda2       269M   53M  198M  22% /boot
cgmfs           100K     0  100K   0% /run/cgmanager/fs
tmpfs            99M   48K   99M   1% /run/user/1000

Important commands for NFS:

exportfs -r - Refresh the server’ s list after modifying /etc/exports
exportfs -u - Unexports all shares listed in /etc/exports, or given name
exportfs -a - Exports all shares listed in /etc/exports, or given name
exportfs -v - Displays a list of shares files and options on a server
showmount -d - Lists all the sub directories
showmount -e : Lists the available shares at the remote server
showmount -e - Shows the available shares on your local machine