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Adding SMB Shares

  12 minute read.

Last Modified 2023-01-18 10:24 EST

About Windows (SMB) Shares

SMB (also known as CIFS) is the native file sharing system in Windows. SMB shares can connect to most operating systems, including Windows, MacOS, and Linux. TrueNAS can use SMB to share files among single or multiple users or devices.

SMB supports a wide range of permissions, security settings, and advanced permissions (ACLs) on Windows and other systems, as well as Windows Alternate Streams and Extended Metadata. SMB is suitable for managing and administering large or small pools of data.

TrueNAS uses Samba to provide SMB services. The SMB protocol has multiple versions. An SMB client typically negotiates the highest supported SMB protocol during SMB session negotiation. Industry-wide, SMB1 protocol (sometimes referred to as NT1) usage is being deprecated for security reasons. However, most SMB clients support SMB 2 or 3 protocols, even when they are not default.

Legacy SMB clients rely on NetBIOS name resolution to discover SMB servers on a network. TrueNAS disables the NetBIOS Name Server (nmbd) by default. Enabled in Network if you require its functionality.

MacOS clients use mDNS to discover SMB servers present on the network. TrueNAS enables the mDNS server (avahi) by default.

Windows clients use WS-Discovery to discover the presence of SMB servers, but network discovery can be disabled by default depending on the Windows client version.

Discoverability through broadcast protocols is a convenience feature and not required to access an SMB server.

Adding an SMB Share

Adding an SMB share to your system involves several steps to add the share and get it working.

First you set up the storage for your new share.

Next you create local user accounts. It is also possible to use Directory Services to provide additional user accounts.

After adding or modifying local users, modify the dataset ACL.

Now you create the SMB share. You can create a basic SMB share or for more specific share types or feature requirements, use the Advanced Options instructions before you save the share.

After adding the share you start the service and mount it to your other system.

Adding an SMB Share Dataset

Before creating the SMB share, first add the dataset the share uses for data storage.

We recommend creating a new dataset with the Share Type set to SMB for the new SMB share.

TrueNAS creates the ZFS dataset with these settings:

  • ACL Mode set to Restricted The ACL Type influences the ACL Mode setting. When ACL Type is set to Inherit or POSIX, you cannot change the ACL Mode setting. When ACL Type is set to NFSv4 you can change the ACL Mode setting to Restricted.

  • Case Sensitivity set to Insensitive

TrueNAS also applies a default access control list to the dataset. This default ACL is restrictive and only allows access to the dataset owner and group. You can modify the ACL later according to your use case.

Creating Local User Accounts

Use Credentials > Local Users to add new users to your TrueNAS.

By default, all new local users are members of a built-in SMB group called builtin_users.

For more information on the builtin_users group, go to Credentials > Local Users and click the Toggle Built-In Users button at the top right of the screen. Scroll down to the smbguest user and click on the name. Click Edit to view the Edit User screen. The Auxiliary Group field displays the builtin_user group.
You can use the group to grant access to all local users on the server or add more groups to fine-tune permissions to large numbers of users.
You cannot access SMB shares with the root user, or user accounts built-in to TrueNAS or those without the smb flag.

Anonymous or guest access to the share is possible, but it is a security vulnerability. Major SMB client vendors are deprecating it, partly because signing and encryption are not possible for guest sessions.

If you want LDAP server users to access the SMB share, go to Credentials > Directory Services. If an LDAP server is configured, select the server and click Edit to display the LDAP configuration screen. If not configured, click Configure LDAP to display the LDAP configuration screen. Click Advanced Options and select Samba Schema (DEPRECATED - see help text.

Only set LDAP authenication for SMB share is required and the LDAP server is already configured with Samba attributes. Support for Samba Schema is officially deprecated in Samba 4.13. This feature will be removed after Samba 4.14. Users should begin upgrading legacy Samba domains to Samba AD domains.

Local TrueNAS user accounts no longer have access to the share.

Tuning the Dataset ACL

After creating a dataset and accounts, you need to investigate your access requirements and adjust the dataset ACL to match. Many home users typically add a new ACL entry that grants FULL_CONTROL to the builtin_users group with the flags set to INHERIT.

To change or add permissions for the builtin_users group, go to Storage,

  1. Click the for your SMB dataset and then click on View Permissions.

  2. Click the edit pencil icon. The Edit ACL screen for the dataset displays.

  3. Check the Access Control List to see if this user is on the list and has the correct permissions. If not add this ACE item.


    a. Enter Group in the Who field or use the dropdown list to select Group.

    b. Begin typing builtin_users in the Group field to display a filtered list of groups you can select from and then select builtin_users.

    c. Verify Full Control displays in Permissions. If not, select it from the dropdown list.

    d. Click Save Access Control List to add the ACE item.

If you want to allows users to move through directories within an SMB share without have read or write access, you must use the Traverse permission. Traverse is useful if you intend to have nested groups within an SMB share that have different levels of access.

See Permissions for more information on editing dataset permissions.

You cannot access SMB shares with the root user. Always change SMB dataset ownership to the intended SMB user.

Creating the SMB Share

To create a basic Windows SMB share, go to Shares.

  1. Click on Windows Shares (SMB) to select it and then click Add. The Add SMB configuration screen displays the Basic Options settings.


  2. Enter the SMB share Path and Name.

    The Path is the directory tree on the local file system that TrueNAS exports over the SMB protocol.

    The Name is the SMB share name, which forms part of the full share pathname when SMB clients perform an SMB tree connect. Because of how the SMB protocol uses the name, it must be less than or equal to 80 characters and it cannot have any invalid characters as specified in Microsoft documentation MS-FSCC section 2.1.6. If you do not enter a name the share name becomes the last component of the path. If you change the name follow the naming conventions for:

  3. (Optional) Select a preset from the Purpose dropdown list to apply and lock or unlock pre-determined Advanced Options settings for the share. To retain control over all the share Advanced Options settings, select No presets.

  4. (Optional) Enter a Description to help explain the share purpose.

  5. Select Enabled to allow sharing of this path when the SMB service is activated. Leave it cleared if you want to disable but not delete the share configuration.

  6. Click Save to create the share and add it to the Shares > Windows (SMB) Shares list.

You can also choose to enable the SMB service at this time.

Configuring Share Advanced Options Settings

For a basic SMB share you do not need to use the Advanced Options settings, but if you set Purpose to No Presets, click Advanced Options to finish customizing the SMB share for your use case.

The following are possible use cases, but for all settings see SMB Shares Screens.

Enabling ACL Support

To add ACL support to the share, select Enable ACL, and then see Managing SMB Shares for more on configuring permissions for the share and the file system.

Setting Up Guest Access

If you want to allow guest access to the share, select Allow Guest Access.

The privileges are the same as the guest account. Guest access is disabled by default in Windows 10 version 1709 and Windows Server version 1903. Additional client-side configuration is required to provide guest access to these clients.

  • MacOS clients: Attempting to connect as a user that does not exist in FreeNAS does not automatically connect as the guest account.

  • Connect As: Guest Specifically choose this option in macOS to log in as the guest account. See the Apple documentation for more details.

Setting Up Read or Write Access

To prohibit writes to the share, select Export Read Only.

To restrict share visibility to users with read or write access to the share, select Access Based Share Enumeration. See the smb.conf manual page.

Setting Up Host Allow and Host Deny

To control allowed or denied host names or IP addresses, use the Host Allow and Host Deny options.

Use the Hosts Allow field to enter a list of allowed hostnames or IP addresses. Separate entries by pressing Enter. You can find a more detailed description with examples here. Use the Hosts Deny field to enter a list of denied hostnames or IP addresses. Separate entries by pressing Enter.

The Hosts Allow and Hosts Deny fields work together to produce different situations:

  • If neither Hosts Allow or Hosts Deny contains an entry, then SMB share access is allowed for any host.
  • If there is a Hosts Allow list but no Hosts Deny list, then only allow hosts on the Hosts Allow list.
  • If there is a Hosts Deny list but no Hosts Allow list, then allow all hosts on the Hosts Deny list.
  • If there is both a Hosts Allow and Hosts Deny list, then allow all hosts on the Hosts Allow list. If there is a host not on the Hosts Allow and not on the Hosts Deny list, then allow it.

Apple Filing Protocol (AFP) Compatibility

AFP shares are deprecated and not available in SCALE. To customize your SMB share to work with a migrated AFP share or with your MacOS, use the Advanced Options settings provided for these uses cases.

Time Machine enables Apple Time Machine backups on this share.

Legacy AFP Compatibility controls how the SMB share reads and writes data. Leave unset for the share to behave like a normal SMB share and set for the share to behave like the deprecated Apple Filing Protocol (AFP). Only set this when this share originated as an AFP sharing configuration. This is not required for pure SMB shares or macOS SMB clients.

Use Apple-style Character Encoding converts NTFS illegal characters in the same manner as MacOS SMB clients. By default, Samba uses a hashing algorithm for NTFS illegal characters.

Starting the SMB Service

To connect to an SMB share you must start the related system service. You can start the service from the Windows SMB Share header on the Sharing screen or on the System Settings > Services screen.

Starting the Service Using the Windows SMB Share

From the main Sharing screen, click on the Windows (SMB) Shares more_vert to display the service options which are Turn Off Service if the service is running or Turn On Service if the service is stopped.


Each SMB share on the list also has a toggle you can use to enable or disable the service for that share.

Starting the Service Using the System Settings

To make SMB share available on the network, go to System Settings > Services and click the toggle to running for SMB. Set Start Automatically if you want the service to activate when TrueNAS boots.

Service Configuration

Configure the SMB service by clicking . Unless you need a specific setting or are configuring a unique network environment, we recommend the default settings.

Mounting the SMB Share

The instructions in this section cover mounting the SMB share on system with the following operating systems.

Mounting on Linux System

Verify that your Linux distribution has the required CIFS packages installed.

Create a mount point: sudo mkdir /mnt/smb_share.

Mount the volume. sudo mount -t cifs //computer_name/share_name /mnt/smb_share.

If your share requires user credentials, add the switch -o username= with your username after cifs and before the share address.

Mounting on Windows System

Have the information on the Windows drive letter, computer name and share name ready before you start.

To mount the SMB share to a drive letter on Windows, open the command line and run the following command with the appropriate drive letter, computer name, and share name.

net use Z: \\computer_name\share_name /PERSISTENT:YES

Mounting on Apple System

Have the user name and password for the user assigned to pool or for the guest if the share has guest access ready before you begin.

Open Finder > Go > Connect To Server Enter the SMB address: smb://

Input the username and password for the user assigned to that pool or guest if the share has guest access.

Mounting on FreeBSD System

Mounting on a FreeBSD system involves creating the mount point and then mounting the volume.

Create a mount point: sudo mkdir /mnt/smb_share.

Mount the volume. sudo mount_smbfs -I computer_name\share_name /mnt/smb_share.

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