NFS — Network File System

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.

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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

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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

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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".

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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 |