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How to diagnose inaccessible SMB sharing

An inaccessible SMB sharing can come from DNS, port 445, the sharing name or permissions. These layers must be tested in this order.

TopicStorage / NAS / SAN →
⌚ About 2 min read
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Windows / SMB Intermediate. 10 min

An inaccessible SMB sharing can come from DNS, port 445, the sharing name or permissions. These layers must be tested in this order.

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

    Validate Name

    Solve the server with its FQDN and check the address obtained.

  2. 2

    Test SMB port

    Check the TPC 445 from the user station.

  3. 3

    Test the UNC path

    Open servershare and leave the exact message.

  4. 4

    Control permissions

    Compare share rights and NTFS rights of user.

  5. 5

    Check the authentication

    If necessary, check existing connections and Kerberos/NTLM context.

Commands utiles

Test-Net-Gone-Meeting Server -Port 445
Net use
The G-Smb-Georgia

À retenir

  • N, enable SMBv1 to solve a simple connectivity problem.
  • The path by IP can work while bypassing Kerberos; this is not a definitive validation.
  • Store the exact code 0x80070035 or 0x80070043 if it appears.
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Technical deep dive

SMB: validate port, authentication, permissions and dialect separately

Technical checkpoints

  • TCP
  • 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.
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