Changes

NFS, or Network File System, is a distributed file system protocol that allows you to mount remote directories on your server. This lets you manage storage space in a different location and write to that space from multiple clients. NFS provides a relatively quick and easy way to access remote systems over a network and works well in situations where the shared resources will be accessed regularly.

In this guide, we'll cover how to configure NFS mounts.

To follow along, you will need:

Throughout the tutorial, we refer to the server that shares its directories as the host and the server that mounts these directories as the client. In order to keep them straight, we’ll use the following IP addresses as stand-ins for the host and client values:

Host: 203.0.113.0

Client: 203.0.113.256

You should replace these values with your own host and client ip addresses.

ls -la /var/nfs/general

Output

NFS will translate any root operations on the client to the nobody:nogroup credentials as a security measure. Therefore, we need to change the directory ownership to match those credentials.

/etc/exports

We’ll need to create a line for each of the directories that we plan to share. Since our example client has an IP of 203.0.113.256, our lines will look like the following. Be sure to change the IPs to match your client:

/etc/exports

We’re using the same configuration options for both directories with the exception of no_root_squash. Let’s take a look at what each one means.

Status: active

On our system, only SSH traffic is being allowed, so we’ll need to add a rule for NFS traffic.

Status: active

This confirms that UFW will only allow NFS traffic on port 2049 from our client machine.

df -h

Output

Both of the shares we mounted appear at the bottom. Because they were mounted from the same file system, they show the same disk usage. To see how much space is actually being used under each mount point, use the disk usage command du and the path of the mount. The -s flag will provide a summary of usage rather than displaying the usage for every file. The -h will print human readable output.

ls -l /nfs/general/general.test

Output

Because we mounted this volume without changing NFS’s default behavior and created the file as the client machine’s root user via the sudo command, ownership of the file defaults to nobody:nogroup. Client superusers won’t be able to perform typical administrative actions, like changing the owner of a file or creating a new directory for a group of users, on this NFS-mounted share.

ls -l /nfs/home/home.test

Output

We created home.test as root via the sudo command, exactly the same way we created the general.test file. However, in this case it is owned by root because we overrode the default behavior when we specified the no_root_squash option on this mount. This allows our root users on the client machine to act as root and makes the administration of user accounts much more convenient. At the same time, it means we don’t have to give these users root access on the host.

/etc/fstab

. . .

Note: More information about the options we are specifying here can be found in the man page that describes NFS mounting in the fstab with the man nfs command.

Output

If you also want to prevent them from being remounted on the next reboot, edit /etc/fstab and either delete the line or comment it out by placing a # symbol at the beginning of the line. You can also prevent auto-mounting by removing the auto option, which will allow you to mount it manually.