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How to check SMB signing

This BAOI guide provides a structured method for checking smbsign without multiplying unnecessary changes.

TopicStorage / NAS / SAN →
⌚ About 2 min read
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Windows Server. Intermediate. 15-30 min

This BAOI guide provides a structured method for checking smbsign without multiplying unnecessary changes.

Avant de commencer : adaptez toujours les commandes et manipulations à votre environnement. Sur un système de production, prévoyez une backup ou un retour arrière lorsque l’action peut modifier la configuration.

Étapes à suivre

  1. 1

    Set perimeter

    Identify the equipment, service, affected users and start time.

  2. 2

    Collect Elements

    Record the exact messages, logs and useful settings.

  3. 3

    Test methodically

    Start with the basic dependencies before the application components.

  4. 4

    Apply correction

    Change only the identified parameter or component.

  5. 5

    Validate

    Rewrite the full scenario and document the result.

À retenir

  • Keep the initial values for a backwards.
  • Avoid multiple simultaneous changes.
  • Compare with a functional configuration when possible.
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Technical deep dive

SMB: validate port, authentication, permissions and dialect separately

Technical checkpoints

  • TCP/445 reachability is necessary but does not validate authentication or share/NTFS permissions.
  • Effective access combines share and NTFS permissions; the most restrictive result applies.
  • SMB Signing and negotiated dialect can explain differences between legacy devices/scanners and modern Windows.

Test chain

Test name/IP, port 445, then share access using the same account as the device.

Test-NetConnection server -Port 445
Get-SmbConnection
net use \\server\share /user:DOMAIN\account

Topic-specific pitfalls

  • Testing with an administrator often hides service-account permission problems.
  • Re-enabling SMB1 for an old scanner greatly increases attack surface; prefer firmware update/replacement.

How to validate

  • The same account used by the application/scanner can create and read a test file in the intended folder.
  • Negotiated dialect/signing match the expected security policy.

Operational diagnosis

SMB signing must be evaluated on both client and server because “enabled” and “required” are different states. Effective behavior depends on both endpoints and the negotiated SMB session.

Step-by-step checks

  1. Read client and server signing settings separately and note whether signing is enabled or required.
  2. Confirm the SMB protocol version and actual negotiated session properties.
  3. Identify legacy devices or applications that cannot meet a new signing requirement before enforcement.
  4. Test representative shares and authentication paths after policy changes.

Useful verification commands

Run only the commands that match the platform you are troubleshooting and capture the output before making a configuration change.

Get-SmbClientConfiguration | Select EnableSecuritySignature,RequireSecuritySignature
Get-SmbServerConfiguration | Select EnableSecuritySignature,RequireSecuritySignature
Get-SmbConnection

How to validate the fix

Existing and new SMB sessions should show the intended signing state, with required clients/servers refusing sessions that cannot satisfy policy.

Evidence to keep

Keep effective SMB configuration, session information and Group Policy source so the result can be reproduced.

Related BAOI resources: IT tools · procedures · IT dictionary.

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