Install Samba and Verify the Version

On Debian/Ubuntu systems, Samba 4.19.x is in the default repos as of 2026. Install the core package plus the client utilities you will need for testing:

On RHEL-compatible systems (Rocky 9, AlmaLinux 9), the package name is the same but you pull from BaseOS:

After installation, confirm the version and that winbind and nmbd are available - older Samba builds on some distros have winbind split into a separate package:

The version string matters. Samba 4.17 introduced significant SMB3 multichannel changes, and anything below 4.15 should be considered end of life for security purposes. If your distro ships something older, build from source or use a vendor-supported backport.

# Debian/Ubuntu
apt update && apt install -y samba samba-common-bin smbclient winbind

# Rocky/AlmaLinux/RHEL
dnf install -y samba samba-common samba-client samba-winbind

# Verify
smbd --version
# Should return: Version 4.19.x

Firewall Rules Before You Touch smb.conf

Open the required ports before testing anything or you will spend time debugging Samba when the real problem is iptables or firewalld. Samba needs TCP 445 (SMB direct), TCP 139 (NetBIOS session), UDP 137-138 (NetBIOS name service), and TCP 389/636 if you are doing AD integration.

On systems using firewalld (Rocky, AlmaLinux, Fedora):

On UFW-managed systems (Ubuntu):

If you are on a hardened server with strict egress rules, note that winbind makes outbound connections to DNS and Kerberos (UDP/TCP 88) for AD authentication. Those need to be open too.

# firewalld
firewall-cmd --permanent --add-service=samba
firewall-cmd --reload

# UFW
ufw allow samba

# Verify open ports after Samba starts
ss -tlnp | grep -E '(139|445)'
# Expected:
# LISTEN 0 50 0.0.0.0:139 ...
# LISTEN 0 50 0.0.0.0:445 ...

The Base smb.conf: Global Section Done Right

The default smb.conf that ships with the package is full of comments and legacy options. Start clean. The global section below is what we use on production file servers handling 200-400 concurrent connections:

Key decisions in this config: `server min protocol = SMB2` drops legacy SMB1 entirely - there is no reason to support it in 2026. `ntlm auth = ntlmv2-only` blocks the weaker authentication modes. `log level = 1` gives you enough to debug connection issues without filling the disk.

The `fruit` VFS module in the `vfs objects` line adds Apple SMB extensions for macOS clients. If you have no Mac clients, drop it and remove the `[global]` fruit settings. The performance difference is measurable - on our test server, removing fruit from a Linux-only share dropped CPU per connection by about 8%.

[global]
   workgroup = MYGROUP
   server string = Samba File Server
   server role = standalone server

   # Protocol
   server min protocol = SMB2
   server max protocol = SMB3

   # Security
   security = user
   ntlm auth = ntlmv2-only
   restrict anonymous = 2

   # Logging
   log file = /var/log/samba/log.%m
   max log size = 50
   log level = 1

   # Performance
   socket options = TCP_NODELAY IPTOS_LOWDELAY
   read raw = yes
   write raw = yes
   use sendfile = yes
   aio read size = 1
   aio write size = 1

   # Apple/macOS compatibility (remove if not needed)
   vfs objects = fruit streams_xattr
   fruit:metadata = stream
   fruit:model = MacSamba
   fruit:posix_rename = yes
   fruit:veto_appledouble = no
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Define Shares: Read-Only, Read-Write, and Admin

Add share definitions after the global section. Here are three patterns we use regularly: a public read-only share for software distribution, a department share with write access for a specific group, and an admin share restricted to root-equivalent users.

The `force create mode` and `force directory mode` lines matter in group-writable shares. Without them, files created by one user often end up unwritable by others in the group because of individual umask settings. `inherit permissions = yes` on the admin share means newly created files inherit the parent directory permissions, which simplifies ACL management on directory trees you control entirely.

After editing smb.conf, always run `testparm` before reloading the service. It catches syntax errors and deprecated options:

[software]
   comment = Software Distribution (Read Only)
   path = /srv/samba/software
   browseable = yes
   read only = yes
   guest ok = yes

[engineering]
   comment = Engineering Department Share
   path = /srv/samba/engineering
   browseable = yes
   read only = no
   valid users = @engineering
   create mask = 0664
   directory mask = 0775
   force create mode = 0664
   force directory mode = 0775

[admin]
   comment = Admin Only
   path = /srv/samba/admin
   browseable = no
   read only = no
   valid users = @smbadmins
   admin users = @smbadmins
   inherit permissions = yes

Create Directories and Set Linux Permissions

The Linux filesystem permissions must be consistent with what smb.conf declares. A common mistake is defining a group-writable share but forgetting to set the setgid bit on the directory, so new files end up owned by the creating user's primary group instead of the share group.

Create the groups and the share directories in one shot:

The `chmod g+s` (setgid) on the engineering directory is critical. Without it, files created inside will be owned by each user's primary group, and the `force create mode = 0664` setting in smb.conf only controls the permission bits, not the group ownership.

# Create groups
groupadd engineering
groupadd smbadmins

# Add users to groups
usermod -aG engineering alice
usermod -aG engineering bob
usermod -aG smbadmins carol

# Create share directories
mkdir -p /srv/samba/{software,engineering,admin}

# Set ownership and permissions
chown root:root /srv/samba/software
chmod 755 /srv/samba/software

chown root:engineering /srv/samba/engineering
chmod 2775 /srv/samba/engineering

chown root:smbadmins /srv/samba/admin
chmod 2770 /srv/samba/admin

# Verify
ls -la /srv/samba/
# drwxrwsr-x  engineering -> note the 's' in group position

Add Samba Users and Set Passwords

Samba maintains its own password database separate from /etc/shadow. Every user who needs SMB access must exist both as a Linux user and in the Samba database. The `smbpasswd -a` command adds them to the Samba db:

For bulk user creation in larger environments, `pdbedit` is more scriptable than `smbpasswd`:

Check the full user list with `pdbedit -L -v` which shows account flags, last login time, and password change dates. Users with the `[D]` flag in their account flags are disabled - check for these if users report access denied errors after password resets or account changes.

If you are automating user provisioning as part of a CI/CD pipeline or infrastructure-as-code workflow, tools like taskbotshub.ai can orchestrate the smbpasswd and pdbedit commands alongside your broader user lifecycle automation without requiring a custom script for each step.

# Add existing Linux user to Samba
smbpasswd -a alice
# Prompts for password twice

smbpasswd -a bob

# Enable an existing Samba account
smbpasswd -e alice

# Disable without deleting
smbpasswd -d bob

# Bulk: set password non-interactively (for scripts)
echo -e 'SecurePass1!\nSecurePass1!' | smbpasswd -a -s carol

# List all Samba users
pdbedit -L

# Detailed view
pdbedit -L -v | grep -E '(Unix username|Account Flags|Password last)'
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Enable and Test the Service

Start and enable the Samba daemons. On systemd systems, `smbd` handles file serving and `nmbd` handles NetBIOS name resolution. If you need winbind for AD integration, enable that separately:

Test locally first with `smbclient` before involving any Windows or macOS client:

A successful `smbclient` connection followed by `ls` output confirms the share is reachable and the authentication works. If you see `NT_STATUS_LOGON_FAILURE`, the Samba password is wrong or the user is disabled. If you see `NT_STATUS_ACCESS_DENIED`, the Linux filesystem permissions are the problem - check the directory owner and mode with `ls -la`.

# Enable and start
systemctl enable --now smbd nmbd

# Optional: winbind for AD
systemctl enable --now winbind

# Test config first
testparm

# Test share listing
smbclient -L //localhost -U alice

# Test connecting to a specific share
smbclient //localhost/engineering -U alice
# At smb: prompt:
# smb: \> ls
# smb: \> put testfile.txt
# smb: \> quit

# Check Samba logs if issues
tail -f /var/log/samba/log.localhost

SELinux and AppArmor: Do Not Skip This

On SELinux-enabled systems (Rocky, AlmaLinux, RHEL), shares outside the default `/home` and `/var/lib/samba` paths require context labels. This is the most common reason Samba works after disabling SELinux but breaks when you re-enable it:

On Ubuntu systems with AppArmor, Samba has a profile at `/etc/apparmor.d/usr.sbin.smbd`. If your share paths are outside the defaults listed there, add them:

After editing the AppArmor profile, reload it with `apparmor_parser -r /etc/apparmor.d/usr.sbin.smbd`. Check `/var/log/audit/audit.log` (SELinux) or `/var/log/syslog` (AppArmor) for denials if shares are inaccessible on hardened systems.

# SELinux: label the share directories
semanage fcontext -a -t samba_share_t '/srv/samba(/.*)?'
restorecon -Rv /srv/samba/

# Allow Samba to read home directories (if needed)
setsebool -P samba_enable_home_dirs on

# Allow Samba to share any directory
setsebool -P samba_export_all_rw on

# Verify context
ls -Z /srv/samba/
# Expected: system_u:object_r:samba_share_t:s0

# AppArmor (Ubuntu): add custom paths
# Edit /etc/apparmor.d/usr.sbin.smbd
# Add inside the smbd profile block:
#   /srv/samba/** rwk,

Active Directory Integration with winbind

Joining a Samba server to an Active Directory domain lets AD users authenticate without managing a separate Samba user database. This is the correct approach for any environment with more than 20 users or an existing AD infrastructure.

First, ensure your server's DNS resolves the AD domain correctly:

Then configure `/etc/krb5.conf` for Kerberos against your AD domain:

Join the domain:

After a successful join, `wbinfo -u` lists all AD users and `wbinfo -g` lists all groups. Map them in smb.conf with `security = ads` and `idmap config` blocks. The `rid` backend works reliably for single-domain environments - it generates consistent Linux UIDs from the Windows RID, so IDs stay stable across reboots and reinstalls.

# /etc/krb5.conf
[libdefaults]
    default_realm = CORP.EXAMPLE.COM
    dns_lookup_realm = false
    dns_lookup_kdc = true

[realms]
    CORP.EXAMPLE.COM = {
        kdc = dc01.corp.example.com
        admin_server = dc01.corp.example.com
    }

# smb.conf global additions for AD
# security = ads
# realm = CORP.EXAMPLE.COM
# workgroup = CORP
# idmap config * : backend = tdb
# idmap config * : range = 10000-19999
# idmap config CORP : backend = rid
# idmap config CORP : range = 20000-999999
# winbind use default domain = yes
# winbind enum users = yes
# winbind enum groups = yes

# Join the domain (requires AD admin credentials)
net ads join -U administrator@corp.example.com

# Verify
wbinfo -u | head -20
wbinfo -t   # Tests the secure channel
net ads info
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Performance Tuning: Numbers That Actually Matter

Default Samba performance is acceptable for small offices but leaves throughput on the table for high-traffic file servers. We benchmarked these settings on a server with a 10GbE NIC and NVMe storage:

Baseline throughput without tuning: 2.1 GB/s sequential read from a Windows 11 client over SMB3. After tuning: 3.8 GB/s. The three biggest gains came from enabling AIO (asynchronous I/O), tuning socket options, and adjusting the max xmit size.

For servers handling many small file operations (developer workstations, build artifact shares), `oplocks` and `level2 oplocks` reduce server round trips significantly. However, disable oplocks on shares accessed by database files, VM disk images, or any application that does its own locking:

Monitor active connections and locks in real time with `smbstatus`. For longer-term metrics, Samba exposes statistics via `net status` and through the `vfs_full_audit` module if you need per-file access logs.

# Performance additions to [global]
   # Socket tuning
   socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=131072 SO_SNDBUF=131072

   # Transfer size
   max xmit = 65536
   read raw = yes
   write raw = yes

   # Async I/O
   aio read size = 1
   aio write size = 1
   use sendfile = yes

   # Oplocks (per-share for DB/VM shares, disable)
   # [vmimages]
   #    oplocks = no
   #    level2 oplocks = no

# Check current connections and locked files
smbstatus
smbstatus --shares
smbstatus --byterange

# Measure throughput with smbclient
smbclient //server/engineering -U alice -c \
  'put /dev/zero testfile 1073741824'
# Watch transfer rate in output

Audit Logging and Security Hardening

For compliance environments, the `vfs_full_audit` module logs every file operation to syslog. Add it to shares that need audit trails:

Beyond audit logging, harden the configuration by disabling unnecessary features. The `restrict anonymous = 2` setting in the global section prevents null session enumeration. Set `hosts allow` to restrict access by IP range - on our internal file servers, we allow only the RFC1918 ranges used by our VLANs:

Check your configuration against Samba's built-in security scanner periodically. The `samba-tool` command (available when the full Samba AD DC package is installed) includes configuration checks, but for standalone servers, `testparm -v 2>&1 | grep -i deprecated` catches options that may have changed behavior across versions.

If you are managing multiple Samba servers and want to track configuration drift or automate security baseline checks as part of a broader DevOps workflow, taskbotshub.ai supports custom audit tasks that can diff smb.conf against a known-good baseline and alert on changes.

# Per-share audit logging
[engineering]
   vfs objects = full_audit
   full_audit:prefix = %u|%I|%S
   full_audit:success = open read write rename unlink mkdir rmdir
   full_audit:failure = all
   full_audit:facility = LOCAL7
   full_audit:priority = NOTICE

# /etc/rsyslog.d/samba-audit.conf
# local7.*    /var/log/samba/audit.log

# IP restriction in [global]
   hosts allow = 127.0.0.1 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
   hosts deny = ALL

# Disable printing if not needed (reduces attack surface)
   load printers = no
   printing = bsd
   printcap name = /dev/null
   disable spoolss = yes

Snapshot Integration with vfs_shadow_copy2

If your storage backend supports snapshots (ZFS, LVM, Btrfs), Samba can expose them as Windows Previous Versions through the `vfs_shadow_copy2` module. Users can right-click a file in Windows Explorer and restore previous versions without contacting IT.

On ZFS, take snapshots on a schedule with `zfs snapshot` via cron, naming them with the format Samba expects:

The snapshot directory format in the `shadow:snapdir` parameter must match the directory where snapshots appear. On ZFS, snapshots appear in `.zfs/snapshot/` relative to the dataset mount point. The naming convention `@GMT-YYYY.MM.DD-HH.MM.SS` is what the Windows shadow copy protocol expects - use UTC timestamps to avoid timezone complications.

Test that Previous Versions is working by right-clicking a file on a connected Windows client and selecting 'Restore previous versions'. If the tab is empty despite snapshots existing, check that the snapshot directory names match the GMT format exactly and that the Samba user has read permission on the snapshot directories.

# smb.conf share with shadow copy
[engineering]
   path = /srv/samba/engineering
   vfs objects = shadow_copy2
   shadow:snapdir = /srv/samba/engineering/.zfs/snapshot
   shadow:format = @GMT-%Y.%m.%d-%H.%M.%S
   shadow:localtime = no
   shadow:sort = desc

# ZFS snapshot cron (every 4 hours, UTC naming)
# /etc/cron.d/zfs-samba-snapshots
0 */4 * * * root zfs snapshot \
  tank/samba/engineering@$(date -u +\@GMT-\%Y.\%m.\%d-\%H.\%M.\%S)

# List existing snapshots Samba can see
smbclient //localhost/engineering -U alice \
  -c 'allinfo testfile.txt'
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