Ubuntu NAS Server: Samba SMB Shares, NFS Exports, and Firewall

Q: How do clients connect to this Ubuntu NAS?

From Windows use \\SERVER\share. From Ubuntu use smb://SERVER/share in Files or mount with cifs-utils. For NFS use showmount -e SERVER then mount -t nfs SERVER:/srv/nas/data /mnt/nas. See the client mount walkthrough in the related article below.

A NAS server on Ubuntu is a spare PC or VM that shares folders over the network—photos, backups, media—without proprietary NAS hardware. You install Samba for SMB/CIFS (what Windows calls a “network drive”) and NFS for Linux clients that want simpler permissions and good throughput on a home LAN.

This guide shows how to build that Linux NAS server on Ubuntu from scratch: storage under /srv/nas, authenticated Samba shares, a read-only guest share, NFS exports restricted to your subnet, firewall rules, and verification with real commands. I ran the full path on Ubuntu 25.04 with Samba 4.21.4 and NFS 2.8.2. For mounting shares from another machine, see how to mount a network drive on Ubuntu—this page is the server side.

Tested on: Ubuntu 25.04 (Plucky Puffin); kernel 6.14.0-37-generic.

WARNING

Do not expose SMB or NFS directly to the public internet. These protocols are for trusted LANs. Use VPN or SSH tunnels if you need remote access.

Quick command summary

Task	Command
Install NAS packages	`sudo apt install -y samba nfs-kernel-server smbclient`
Create data paths	`sudo mkdir -p /srv/nas/data /srv/nas/public`
Add Samba user	`sudo useradd -m -s /usr/sbin/nologin nasuser` then `sudo smbpasswd -a nasuser`
Validate Samba config	`sudo testparm -s`
Restart services	`sudo systemctl restart smbd nmbd nfs-server`
List SMB shares	`smbclient -L //SERVER -U nasuser`
List NFS exports	`showmount -e SERVER`
Open firewall (LAN)	`sudo ufw allow OpenSSH` then `sudo ufw allow from 192.168.0.0/16 to any port 445 proto tcp`

Replace SERVER with your NAS hostname or LAN IP (for example 192.168.0.10), not 127.0.0.1 when testing from other computers.

Before you start

You need:

Ubuntu 22.04 LTS, 24.04 LTS, or newer (Server or Desktop; I used Desktop 25.04).
A dedicated data disk or partition for /srv/nas when possible—see check disk space on Linux before you commit terabytes.
A static IP or DHCP reservation so clients always reach the same address.
sudo on the NAS host.

Ubuntu Desktop works as a home NAS; Ubuntu Server drops the GUI but follows the same Samba and NFS steps. Dedicated NAS operating systems add volume management and apps out of the box—Ubuntu trades that for flexibility and packages you already know.

Step 1: Install Samba and NFS server packages

bash

sudo apt update
sudo apt install -y samba nfs-kernel-server smbclient

On my host:

text


Setting up samba (2:4.21.4+dfsg-1ubuntu3.5) ...
Created symlink ... smbd.service
Created symlink ... nmbd.service

Check versions:

bash

apt-cache policy samba nfs-kernel-server | grep Candidate

text

Candidate: 2:4.21.4+dfsg-1ubuntu3.5
  Candidate: 1:2.8.2-2ubuntu1

Step 2: Plan storage under /srv/nas

Create export directories on a disk with enough free space:

bash


sudo mkdir -p /srv/nas/data /srv/nas/public
sudo chmod 2775 /srv/nas/data /srv/nas/public

For a private authenticated share, ownership must match the Samba account or writes fail with NT_STATUS_ACCESS_DENIED—that caught me on the first smbclient put test until I fixed permissions.

Mount a separate disk at /srv/nas in production (for example an ext4 volume in /etc/fstab). Using only the root filesystem works for a lab but is risky when / fills up.

Step 3: Create a Samba user

SMB credentials are separate from your Ubuntu login unless you sync them manually. Create a service account:

bash


sudo useradd -m -s /usr/sbin/nologin nasuser
sudo smbpasswd -a nasuser
sudo smbpasswd -e nasuser

Enter a strong password when prompted. Clients use nasuser and this password—not your Ubuntu desktop password unless you set them the same on purpose.

Give the account ownership of the private data tree:

bash

sudo chown -R nasuser:nasuser /srv/nas/data

Step 4: Configure Samba shares

Back up the default config, then append share definitions to /etc/samba/smb.conf:

bash


sudo cp -a /etc/samba/smb.conf /etc/samba/smb.conf.bak.$(date +%F)
sudo tee -a /etc/samba/smb.conf <<'EOF'

[nas-private]
   path = /srv/nas/data
   browseable = yes
   read only = no
   guest ok = no
   valid users = nasuser
   create mask = 0664
   directory mask = 0775

[nas-public]
   path = /srv/nas/public
   browseable = yes
   read only = yes
   guest ok = yes
EOF

Validate syntax:

bash

sudo testparm -s

Near the end of the output you should see your shares:

text


[nas-private]
	path = /srv/nas/data
	read only = No
	valid users = nasuser

[nas-public]
	guest ok = Yes
	path = /srv/nas/public

Restart Samba:

bash


sudo systemctl restart smbd nmbd
sudo systemctl enable smbd nmbd
systemctl is-active smbd nmbd

text

active
active

Step 5: Export NFS to your LAN

Edit /etc/exports and allow only your local subnet—adjust the CIDR to match your router:

bash


echo '/srv/nas/data 192.168.0.0/24(rw,sync,no_subtree_check,no_root_squash)' | sudo tee -a /etc/exports
sudo exportfs -ra
sudo systemctl enable nfs-server
sudo systemctl restart nfs-server

List exports:

bash

showmount -e localhost

text

Export list for localhost:
/srv/nas/data 192.168.0.0/24

no_root_squash lets root on trusted LAN clients write as root—convenient on a home lab, too loose for shared networks. Tighten options if the NAS sits on untrusted Wi‑Fi.

Step 6: Open the firewall (UFW)

If UFW is inactive, add rules before you enable it. Allow SSH first so you do not lock yourself out of a remote NAS:

bash

sudo ufw allow OpenSSH comment 'SSH admin access'

Replace 192.168.0.0/16 with your LAN subnet. Check the NAS address with hostname -I and your router’s DHCP range (common home nets use 192.168.0.0/24 or 192.168.1.0/24):

bash


sudo ufw allow from 192.168.0.0/16 to any port 445 proto tcp comment 'Samba SMB'
sudo ufw allow from 192.168.0.0/16 to any port 139 proto tcp comment 'Samba NetBIOS'
sudo ufw allow from 192.168.0.0/16 to any port 2049 comment 'NFS'
sudo ufw enable
sudo ufw status numbered

On my test host after ufw enable:

text


Status: active

     To                         Action      From
     --                         ------      ----
[ 1] OpenSSH                    ALLOW IN    Anywhere                   # SSH admin access
[ 2] 445/tcp                    ALLOW IN    192.168.0.0/16             # Samba SMB
[ 3] 139/tcp                    ALLOW IN    192.168.0.0/16             # Samba NetBIOS
[ 4] 2049                       ALLOW IN    192.168.0.0/16             # NFS
[ 8] OpenSSH (v6)               ALLOW IN    Anywhere (v6)              # SSH admin access

Samba still answered on localhost after the firewall went active (smbclient -L //127.0.0.1 listed the shares). Traffic from addresses outside the allowed CIDR is dropped—adjust the subnet if clients cannot connect.

IMPORTANT

NFS may also use RPC on port 111 on some older setups. On Ubuntu 25.04 with nfs-kernel-server 2.8.2, opening 2049/tcp and udp was enough in my test. If showmount fails through the firewall, add sudo ufw allow from 192.168.0.0/16 to any port 111 and retest.

Confirm listeners are still bound:

bash

ss -tlnp | grep -E ':445|:139|:2049'

text


LISTEN 0      50           0.0.0.0:445        0.0.0.0:*
LISTEN 0      50           0.0.0.0:139        0.0.0.0:*
LISTEN 0      64           0.0.0.0:2049       0.0.0.0:*

Step 7: Verify from the NAS host

Seed a test file:

bash


echo 'NAS lab ok' | sudo tee /srv/nas/data/welcome.txt
sudo chown nasuser:nasuser /srv/nas/data/welcome.txt

List SMB shares:

bash

smbclient -L //127.0.0.1 -U nasuser

text


Sharename       Type      Comment
	---------       ----      -------
	nas-private     Disk
	nas-public      Disk

Upload through SMB (after ownership fix):

bash

smbclient //127.0.0.1/nas-private -U nasuser -c 'put /etc/hostname smb-test-hostname.txt; ls'

text


putting file /etc/hostname as \smb-test-hostname.txt
  welcome.txt
  smb-test-hostname.txt

Mount with CIFS locally (optional smoke test):

bash


sudo mkdir -p /mnt/nas-test
sudo mount -t cifs //127.0.0.1/nas-private /mnt/nas-test \
  -o username=nasuser,password=YOUR_PASSWORD,vers=3.0,uid=$(id -u),gid=$(id -g)
df -hT /mnt/nas-test

text

//127.0.0.1/nas-private cifs   58G   44G   15G  76% /mnt/nas-test

Mount NFS (from a client on the allowed subnet):

bash


sudo mkdir -p /mnt/nas-nfs
sudo mount -t nfs NAS_IP:/srv/nas/data /mnt/nas-nfs
ls /mnt/nas-nfs

Use your NAS LAN address instead of 127.0.0.1 when testing from another PC.

Step 8: Connect clients

Client	How to connect
Windows	File Explorer → `\\NAS_IP\nas-private` → sign in as `nasuser`
macOS	Finder → Go → Connect to Server → `smb://NAS_IP/nas-private`
Ubuntu GUI	Files → Other Locations → `smb://NAS_IP/nas-private`
Ubuntu CLI	`sudo mount -t cifs //NAS_IP/nas-private /mnt/nas -o credentials=/root/.smbcredentials,vers=3.0`

For permanent client mounts, credentials files, and fstab with _netdev, use the client mount guide linked at the top of this page.

Common pitfalls

Issue	What goes wrong	Fix
Share name vs hostname	Clients use the PC name instead of the `[share]` block in smb.conf	The share name is the bracketed name (`nas-private`), not the machine hostname
Wrong IP in fstab	`192.1.168.x` typos or using `127.0.0.1` from other PCs	Use the NAS LAN IP from `hostname -I`
SMB version mismatch	Old NAS firmware needs SMB1	Prefer `vers=3.0`; avoid SMB1 unless a legacy device requires it
`NT_STATUS_ACCESS_DENIED` on write	Export path owned by root	`sudo chown -R nasuser:nasuser /srv/nas/data`
NFS mount hangs at boot	Server offline during boot	On clients, use `_netdev` and `x-systemd.automount` in fstab
Full root disk	Samba still runs but OS becomes unstable	Store data on a dedicated volume; monitor with `df`

Optional next steps

Automated snapshots: timeshift or BTRFS snapshots on the data volume.
Remote sync: syncthing between your NAS and laptops (see must-have Ubuntu apps).
Malware scans on shares: periodic ClamAV sweeps when Windows clients use Samba (see does Ubuntu need antivirus?).
Media serving: Jellyfin or Plex in Docker—outside the scope of basic Samba/NFS but common on Ubuntu home servers.
Second disk mirror: mdadm RAID1 or ZFS mirror for redundancy—not a backup by itself.

Remove the NAS services

bash


sudo umount /mnt/nas-test /mnt/nas-nfs 2>/dev/null || true
sudo systemctl stop smbd nmbd nfs-server
sudo apt purge -y samba nfs-kernel-server
sudo rm -rf /srv/nas
# Restore smb.conf if you kept a .bak file

Troubleshooting

Symptom	Likely cause	Fix
`testparm` fails	Syntax error in smb.conf	Run `sudo testparm` without `-s` to see the line number
Shares missing in `smbclient -L`	Stanzas inside wrong section	Put `[nas-private]` at the end of smb.conf, not inside `[print$]`
`exportfs: access denied`	Path not exported	Check `/etc/exports`; run `sudo exportfs -rav`
Client `mount error(13)`	Bad password or user	Test `smbclient //NAS/nas-private -U nasuser%pass` first
NFS `access denied by server`	Client IP outside export CIDR	Widen or fix the subnet in `/etc/exports`
`Job for smbd.service failed`	AppArmor or SELinux rare on Ubuntu	Check `sudo journalctl -u smbd -n 30`

References

Summary

To run a NAS server on Ubuntu, install samba and nfs-kernel-server, create /srv/nas/data, add [nas-private] and optional guest shares to /etc/samba/smb.conf, enable users with smbpasswd, and export the same path in /etc/exports for your LAN subnet. Open 445 and 2049 in UFW, verify with testparm, smbclient, and showmount, then point Windows and Linux clients at \\SERVER\nas-private or smb://SERVER/nas-private. Keep data off the root disk, fix Unix ownership on the export path, and configure client fstab entries with _netdev on other machines.

Frequently Asked Questions

1. Can you use Ubuntu as a NAS server?

Yes. Install Samba for SMB/CIFS shares that Windows, macOS, and Linux clients can map, and nfs-kernel-server for high-throughput NFS on your LAN. Ubuntu Desktop or Server both work; dedicate a data disk under /srv/nas and avoid filling the root filesystem.

2. What is the difference between Samba and NFS on an Ubuntu NAS?

Samba speaks SMB/CIFS—the protocol Windows and most consumer NAS boxes use. NFS is common between Linux machines and often faster for large sequential transfers on a trusted LAN. Many home setups run both: Samba for mixed clients, NFS for Linux desktops and VMs.

3. Which packages do I need for a NAS on Ubuntu?

Install samba for SMB sharing and nfs-kernel-server for NFS exports. Add smbclient on the server for local testing. Clients need cifs-utils and nfs-common—covered in the mount guide linked from this article.

4. Where should NAS files be stored on Ubuntu?

Use a dedicated mount point such as /srv/nas/data on a separate disk or partition—not your root / volume. Check free space with df before you copy terabytes of data. Ext4 or XFS on the data disk is typical for home NAS builds.

5. How do I create a Samba user for NAS shares?

Create a Linux account with sudo useradd, then run sudo smbpasswd -a USERNAME to set the SMB password and sudo smbpasswd -e USERNAME to enable it. valid users = USERNAME in smb.conf restricts the share to that account.

6. Why do SMB clients get Permission denied on a new Ubuntu NAS?

Wrong SMB password, missing smbpasswd user, or Unix ownership on the export path are the usual causes. chown the data directory to the Samba user and test with smbclient -L //SERVER -U user%pass before clients mount.

7. Which firewall ports does an Ubuntu NAS need?

Open TCP 445 and 139 for Samba, and TCP/UDP 2049 for NFS on your LAN interface. Use sudo ufw allow from 192.168.0.0/16 to any port 445 proto tcp style rules instead of exposing shares to the internet.

8. How do clients connect to this Ubuntu NAS?

From Windows use \SERVER\share. From Ubuntu use smb://SERVER/share in Files or mount with cifs-utils. For NFS use showmount -e SERVER then mount -t nfs SERVER:/srv/nas/data /mnt/nas. See the client mount walkthrough in the related article below.