Guide to NFS on Linux

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What is NFS?

NFS (Network File System) allows Linux systems to share directories and files with others over a network. It is commonly used for centralizing storage and making files accessible to multiple machines.

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NFS Architecture

• NFS Server: The machine that shares its directories.
• NFS Client: The machine that mounts and accesses the shared directories.

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Prerequisites

• Two Linux machines on the same network.

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Setting Up NFS: Step-by-Step

1. Install NFS Packages

On Ubuntu/Debian:

sudo apt update
sudo apt install nfs-kernel-server nfs-common

On CentOS/Fedora/RHEL:

sudo yum install nfs-utils

• nfs-kernel-server: Provides the NFS server functionality.
• nfs-common/nfs-utils: Provides client utilities.

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2. Create a Directory to Share

sudo mkdir -p /srv/nfs/shared
sudo chown nobody:nogroup /srv/nfs/shared
sudo chmod 777 /srv/nfs/shared

• chown and chmod: Set permissions so all clients can access it.

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3. Configure NFS Exports

Edit the exports file:

sudo nano /etc/exports

Add a line like:

/srv/nfs/shared 192.168.1.0/24(rw,sync,no_subtree_check)

• rw: Read/write access.
• sync: Writes changes to disk before replying.
• no_subtree_check: Disables subtree checking for better performance.

• Replace 192.168.1.0/24 with your network

  subnet.

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4. Export the Shared Directory

sudo exportfs -ra

• -ra: Re-exports all directories listed in /etc/exports.

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5. Start and Enable NFS Server

sudo systemctl enable --now nfs-server

• Starts the NFS server and enables it at boot.

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6. Adjust Firewall (if enabled)

On Ubuntu:

sudo ufw allow from 192.168.1.0/24 to any port nfs

• 192.168.1.0 replace with your own ip/subnet ip

On CentOS/Fedora:

sudo firewall-cmd --permanent --zone=public --add-service=nfs
sudo firewall-cmd --reload

• Allows NFS traffic through the firewall.

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7. Check NFS Exports

showmount -e

• Lists exported directories on the server.

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NFS Client Configuration

1. Install NFS Client Utilities

On Ubuntu/Debian:

sudo apt install nfs-common

On CentOS/Fedora/RHEL:

sudo yum install nfs-utils

• Installs the client-side tools.

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2. Mount the NFS Share

sudo mkdir -p /mnt/nfs-client
sudo mount -t nfs 192.168.1.100:/srv/nfs/shared /mnt/nfs-client

• Replace 192.168.1.100 with the server’s IP address.
• /mnt/nfs-client is the local mount point.

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3. Make the Mount Permanent

Edit /etc/fstab:

sudo nano /etc/fstab

Add:

192.168.1.100:/srv/nfs/shared /mnt/nfs-client nfs defaults 0 0

• Ensures the share mounts at boot.

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4. Unmount the NFS Share

sudo umount /mnt/nfs-client

• Unmounts the share from the client.[10]

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Export Options

• ro: Read-only access.
• no_root_squash: Allows root on client to act as root on server (use with caution).
• all_squash: Maps all client users to anonymous user.
• anonuid/anongid: Set UID/GID for anonymous users.

NFS Versions

• NFSv3: Widely supported, stateless.
• NFSv4: Improved security, stateful, supports ACLs and pseudo-root.

Security Best Practices

• Restrict access to trusted IPs.
• Use firewalls to limit NFS ports.
• Prefer NFSv4 for better security features.

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Troubleshooting

• Check NFS status: sudo systemctl status nfs-server
• View logs: journalctl -xe | grep nfs
• Test connectivity: showmount -e 192.168.1.100
• Remount all: sudo mount -a
• Check permissions: Ensure directory and export permissions are correct.

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Example: Full Workflow

On Server:

sudo apt install nfs-kernel-server
sudo mkdir -p /srv/nfs/shared
sudo chown nobody:nogroup /srv/nfs/shared
sudo chmod 777 /srv/nfs/shared
echo "/srv/nfs/shared 192.168.1.0/24(rw,sync,no_subtree_check)" | sudo tee -a /etc/exports
sudo exportfs -ra
sudo systemctl enable --now nfs-server

On Client:

sudo apt install nfs-common
sudo mkdir -p /mnt/nfs-client
sudo mount -t nfs 192.168.1.100:/srv/nfs/shared /mnt/nfs-client

• Now, files placed in /srv/nfs/shared on the server will appear in /mnt/nfs-client on the client.

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Thank You