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Disable guest file sharing over SMB

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Works with any MacWorks with any Mac running macOS/OS X on Intel or Apple Silicon.
  • macOS onlyThis script improves your privacy on macOS
  • Single actionThis page belongs to a script, containing basic changes to achieve a task.
  • Impact: Medium

    System Functionality / Data Loss Risk: Moderate

    This action improves privacy with minimal impact when you run the recommended script.

    This action improves privacy with some impact when you run the recommended script.
  • Bash (Shell script)These changes use macOS system commands to update your settings.
  • Administrative (sudo) access requiredThis script requires privilege access to do the system changes
  • Fully reversible

    You can fully restore this action (revert back to the original behavior) using this website.

    The restore/revert methods provided here can help you fix issues.

Overview​

This script prevents anonymous (guest) users from accessing files shared over the SMB protocol.

By default, macOS allows guest users to access shared folders without authentication 1 2.

macOS allows users to share entire systems or specific folders with others on a network 3. This script impacts only SMB sharing 4, meaning that it has no impact on other file sharing alternatives. SMB (Server Message Block) is a network system that allows computers to share files 4 5 6. It is commonly used to share files between Mac and Windows computers 7.

The Guest User feature in macOS lets people temporarily access a Mac without creating standard user accounts 8. Additionally, Guest User accounts on macOS:

  • Do not require a password to log in 8
  • Are restricted from changing system settings 8
  • Cannot access the Mac remotely 8
  • Automatically delete all files when logging out 8
  • Can only use Safari when FileVault encryption is enabled 8
  • Enable Mac location through Find My app if lost 8

Disabling SMB guest sharing blocks unauthorized access to shared folders. This improves your security and privacy by preventing unauthorized users from:

  • Accessing your shared files and folders 4 9
  • Performing network reconnaissance 4
  • Potentially exploiting system vulnerabilities for privilege escalation 4

This security measure is recommended by major security organizations:

  • NIST (National Institute of Standards and Technology) - The official US government cybersecurity standards agency 9
  • Center for Internet Security (CIS) - A leading nonprofit organization that creates security guidelines used worldwide 4

This script may also provide a performance benefit by reducing overhead for guest connections.

Caution

After using this script, you must manually add user accounts for anyone who needs to access your shared files 3.

Technical Details​

The script:

  • Configures the system preference for guest access (/Library/Preferences/SystemConfiguration/com.apple.smb.server!AllowGuestAccess) 4 9
  • Disables SMB guest access using the sysadminctl with -smbGuestAccess off option 10 sysadminctl is a tool used to administer system user accounts 10.
Use with Caution

This script is only recommended if you understand its implications.

Some non-critical or features may no longer function correctly after running this script.

This script can be fully reversed to restore changes if something goes wrong.

Sources
PrivacyLearn.com maintains strict sourcing standards for accuracy, integrity and up-to-date content. Our content relies on authoritative sources including vendor documentation, industry standards, and verified research. Learn more about our verification process and quality standards in our editorial standards page.

Apply Now​

Choose one of three ways to apply:

Download script​

Download and run the script directly
  • No app needed
  • Offline usage
  • Free
  • Open-source
Help

How to apply or restore "Disable guest file sharing over SMB" using script​

  • ≈ 3 min to complete
  • Tools: Web Browser
  • Difficulty: Medium
  • ≈ 5 instructions
  1. 1

    Download

    Download the script file by clicking on the   Apply protection  button above.
    Use   Undo protection button above to restore changes.
  2. 2

    Keep the file

    If warned by your browser, keep the file.
  3. 3

    Open

    Open the downloaded file.
  4. 4

    Exit

    Once it's done, press any key to exit the window.
  5. 5

    Restart

    Restart your computer for all changes to take effect.

Apply with privacy.sexy​

Guided, automated application with safety checks
  • Recommended for most users
  • Includes safety checks
  • Free
  • Open-source
  • Popular
  • Offline/Online usage
Open privacy.sexy
Help

How to apply or restore "Disable guest file sharing over SMB" using privacy.sexy​

  • ≈ 3 min to complete
  • Tools: privacy.sexy
  • Difficulty: Simple
  • ≈ 4 instructions
privacy.sexy is free and open-source application that lets securely apply this action easily with more advanced options.
  1. 1

    Open or download

    Open or download the desktop application
  2. 2

    Choose script

    1. Search for the script name: Disable guest file sharing over SMB
    2. Check the script by clicking on the checkbox.
  3. 3

    Run

    Click on ▶️ Run button at the bottom of the page.

    This button only appears on desktop version (recommended). On browser, use 💾 Save button.

Run commands​

Copy and run commands manually Requires technical knowledge
Apply changes
sudo defaults write '/Library/Preferences/SystemConfiguration/com.apple.smb.server' 'AllowGuestAccess' -bool NO
if ! command -v 'sysadminctl' &> /dev/null; then
    echo 'Skipping because "sysadminctl" is not found.'
else
    sudo sysadminctl -smbGuestAccess off
fi
Help

How to apply or restore "Disable guest file sharing over SMB" using commands​

  • ≈ 2 min to complete
  • Tools: Terminal app
  • Difficulty: undefined
  • ≈ 3 instructions
  1. 1

    Open terminal

    Open Terminal app.
  2. 2

    Copy code

    Copy the code:
    Copy Apply Code Copy Revert Code
  3. 3

    Paste & run

    Paste the code into Terminal and press Enter to run.

    Some changes require a system restart to take effect

Similar Guides​

Wider Goal​

Guides below includes this guide to achieve a wider goal.

See other more general settings that includes this one as one of its actions.

These plans combine multiple privacy settings, including this one, for stronger protection.

These scripts control guest access on macOS to protect your system's security and privacy. Guest access lets anyone use your Mac without a password or account. Thi...
Visit category page

Same Goal​

Other guides in Disable guest accounts 

See settings that are in the same category as this guide.

Using other actions in the same category may help you achieve your goal better.

Disable guest account login
Disable guest file sharing over AFP

About the Creators​

These people have authored this documentation and written its scripts:

  • Avatar of undergroundwires. The creator of PrivacyLearn and privacy.sexy. Black and white portrait showing a person wearing a polka dot tie and suit jacket, reflecting the professional expertise behind the privacy protection tools.
    • Certified security professional
    • 7+ years experience securing banks
    • Open-source developer since 2005
    • EU advisor, Public Speaker, Moderator
    • Hundreds across the globe
    • Testers, reviewers, developers
    • Companies, military agencies
    • Community since 2017
About Us

Reviewed By​

This guide has undergone comprehensive auditing and peer review:

  • Expert review by undergroundwires​

    • Verified technical accuracy and editorial standards
    • Assessed system impact and user privacy risks

  • Public review by large community​

    • Privacy enthusiasts and professionals peer-reviewed
    • Millions of end-users tested across different environments

History​

We continually monitor our guides, their impact and all other privacy options. We update our guides when new information becomes available. On every update, we publicly store who made the change, what has been changed, why the change was made and when the change was made.

Review Change History Our Change Process