NFS File Sharing

Networking 2026-08-28

Native Linux file sharing at near-local disk speeds. Best for Linux-to-Linux sharing on a trusted LAN. NFS state is bind-mounted from /data/varlib/nfs and persists across OS updates.

Prefer Samba if you need to share with Windows or macOS clients. Use NFS for Linux-to-Linux shares where performance matters.

Server Setup

1. Enable NFS Server

sudo systemctl enable --now nfs-server

2. Define Exports

Edit /etc/exports:

# /etc/exports
# Syntax: /path  allowed_clients(options)

# Read-write share for LAN clients
/home/user/shared     192.168.1.0/24(rw,sync,no_subtree_check)

# Read-only share (e.g. for media)
/srv/media            192.168.1.0/24(ro,sync,no_subtree_check)

# Single trusted host with full root access (backup/cluster use only)
/var/backups          192.168.1.5(rw,sync,no_subtree_check,no_root_squash)

Common export options:

Option	Effect
`rw`	Read/write access (default: `ro`)
`sync`	Wait for writes to commit to disk before replying (safer, slightly slower)
`no_subtree_check`	Improves performance when exporting a subdirectory; recommended
`root_squash`	(Default) Maps remote root UID to `nfsnobody` — prevents privilege escalation
`no_root_squash`	⚠️ Allows remote root to act as root on the share. Use only on trusted hosts

3. Apply & Verify

# Re-read /etc/exports without restarting the server
sudo exportfs -arv

# Check which exports are active
showmount -e localhost

4. Firewall

sudo firewall-cmd --add-service=nfs --add-service=rpcbind --add-service=mountd --permanent
sudo firewall-cmd --reload

Client — Mounting

Temporary Mount

sudo mkdir -p /mnt/remote
sudo mount -t nfs 192.168.1.100:/home/user/shared /mnt/remote

# Unmount
sudo umount /mnt/remote

Persistent Mount (`/etc/fstab`)

192.168.1.100:/home/user/shared  /mnt/remote  nfs  defaults,_netdev,nfsvers=4,timeo=14  0 0

Option	Effect
`_netdev`	Delays mount until the network interface is up
`nfsvers=4`	Forces NFSv4 — more firewall-friendly and secure than v3
`timeo=14`	Timeout in tenths of a second before retrying (1.4 s); reduces boot hang if server is down

Apply without rebooting:

sudo mount -a

Disk Quotas (quota-tools)

quota-tools enforces per-user and per-group disk usage limits on NFS-exported filesystems. Quotas are enforced on the server side — limits apply regardless of which client is writing.

Enable Quotas on the Server

# 1. Mount the filesystem with quota options in /etc/fstab
#    Add usrquota and/or grpquota to the options field:
#    /dev/sdb1  /srv/shared  ext4  defaults,usrquota,grpquota  0 2

# 2. Remount to apply the new options
sudo mount -o remount /srv/shared

# 3. Initialise the quota database files
sudo quotacheck -cug /srv/shared

# 4. Enable quota enforcement
sudo quotaon /srv/shared

Set User Quotas

# Edit quotas for a specific user (opens an editor)
sudo edquota -u alice

# The editor shows soft/hard limits for blocks (KB) and inodes (file count):
# Filesystem  blocks   soft   hard  inodes  soft  hard
# /srv/shared  102400  900000 1000000   512  4500  5000
#
# soft = warning threshold; hard = absolute limit
# grace period applies when usage is between soft and hard limits

# Set the grace period (how long a user can exceed soft limit before hard limit kicks in)
sudo edquota -t

# Copy one user's quota settings to another user
sudo edquota -p alice bob

Reporting

# Show quota usage for all users on a filesystem
sudo repquota /srv/shared

# Show your own quota usage
quota -s

# Show quota for a specific user
sudo quota -su alice

NFS + Quotas

NFS clients do not enforce quotas locally — writes that exceed a quota are rejected by the server with an EDQUOT (disk quota exceeded) error, which the client reports as "no space left on device".

Troubleshooting

Issue	Solution
`Permission denied`	Check the client IP is within the allowed range in `/etc/exports`; also verify Linux filesystem permissions on the export path
`Stale file handle`	The exported path was deleted or the server restarted while the client had it open — `sudo umount -f /mnt/remote` and remount
`Access denied by server`	Check `journalctl -u nfs-server` on the host for detailed errors
Mount hangs at boot	Add `_netdev` and `timeo=14` to fstab options; ensure `nfs-server` is running on the host
`showmount` fails from client	Open `rpcbind` and `mountd` firewall services on the server in addition to `nfs`