Test

Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere
OpenSSH (v6)               ALLOW       Anywhere (v6)

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

With many applications, you can use sudo ufw app list and enable them by name, but nfs is not one of those. However, because ufw also checks /etc/services for the port and protocol of a service, you can still add NFS by name. Best practice recommends that you enable the most restrictive rule that will still allow the traffic you want to permit, so rather than enabling traffic from just anywhere, you’ll be specific.

Use the following command to open port 2049 on the host, being sure to substitute your client public IP address:

1. sudo ufw allow from client_ip to any port nfs

You can verify the change by typing:

1. sudo ufw status

You should see traffic allowed from port 2049 in the output:

Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                 
2049                       ALLOW       client_ip        
OpenSSH (v6)               ALLOW       Anywhere (v6)

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

Step 5 — Creating Mount Points and Mounting Directories on the Client

Now that the host server is configured and serving its shares, you’ll prepare your client.

In order to make the remote shares available on the client, you need to mount the directories on the host that you want to share to empty directories on the client.

You’ll create two directories for your mounts on the client machine:

1. sudo mkdir -p /nfs/general
2. sudo mkdir -p /nfs/home

Now that you have a location to put the remote shares and you’ve opened the firewall, you can mount the shares using the IP address of your host server:

1. sudo mount host_ip:/var/nfs/general /nfs/general
2. sudo mount host_ip:/home /nfs/home

These commands will mount the shares from the host computer onto the client machine. You can double-check that they mounted successfully in several ways. You can check this with a mount or findmnt command, but the df -h command, which lists available disk space, provides a more readable output:

1. df -h

Filesystem                   Size  Used Avail Use% Mounted on
tmpfs                        198M  972K  197M   1% /run
/dev/vda1                     50G  3.5G   47G   7% /
tmpfs                        989M     0  989M   0% /dev/shm
tmpfs                        5.0M     0  5.0M   0% /run/lock
/dev/vda15                   105M  5.3M  100M   5% /boot/efi
tmpfs                        198M  4.0K  198M   1% /run/user/1000
10.124.0.3:/var/nfs/general   25G  5.9G   19G  24% /nfs/general
10.124.0.3:/home              25G  5.9G   19G  24% /nfs/home

Both of the shares you 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 provides a summary of usage rather than displaying the usage for every file. The -h prints human-readable output.

For example:

1. du -sh /nfs/home

36K    /nfs/home

This shows us that the contents of the entire home directory is using only 36K of the available space.

Step 6 — Testing NFS Access

Next, test access to the shares by writing something to each of them.

Example 1: The General Purpose Share

First, write a test file to the /var/nfs/general share:

1. sudo touch /nfs/general/general.test

Then, check its ownership:

1. ls -l /nfs/general/general.test

-rw-r--r-- 1 nobody nogroup 0 Apr 18 00:02 /nfs/general/general.test

Because you 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.

Example 2: The Home Directory Share

To compare the permissions of the General Purpose share with the Home Directory share, create a file in /nfs/home the same way:

1. sudo touch /nfs/home/home.test

Then look at the ownership of the file:

1. ls -l /nfs/home/home.test

-rw-r--r-- 1 root root 0 Apr 18 00:03 /nfs/home/home.test

You created home.test as root using the sudo command, exactly the same way you created the general.test file. However, in this case it is owned by root because you overrode the default behavior when you specified the no_root_squash option on this mount. This allows your 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 you don’t have to give these users root access on the host.

Step 7 — Mounting the Remote NFS Directories at Boot

You can mount the remote NFS shares automatically at boot by adding them to /etc/fstab file on the client.

Open this file with root privileges in your text editor:

1. sudo nano /etc/fstab

At the bottom of the file, add a line for each of your shares. They will look like this:

. . .
host_ip:/var/nfs/general    /nfs/general   nfs auto,nofail,noatime,nolock,intr,tcp,actimeo=1800 0 0
host_ip:/home               /nfs/home      nfs auto,nofail,noatime,nolock,intr,tcp,actimeo=1800 0 0

Make sure you save and close this file so that your changes take effect.

The client will automatically mount the remote partitions at boot, although it may take a few moments to establish the connection and for the shares to be available.

Step 8 — Unmounting an NFS Remote Share

If you no longer want the remote directory to be mounted on your system, you can unmount it by moving out of the share’s directory structure and unmounting, like this:

1. cd ~
2. sudo umount /nfs/home
3. sudo umount /nfs/general

Take note that the command is named umount not unmount as you may expect.

This will remove the remote shares, leaving only your local storage accessible:

1. df -h

Filesystem      Size  Used Avail Use% Mounted on
tmpfs           198M  972K  197M   1% /run
/dev/vda1        50G  3.5G   47G   7% /
tmpfs           989M     0  989M   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
/dev/vda15      105M  5.3M  100M   5% /boot/efi
tmpfs           198M  4.0K  198M   1% /run/user/1000