Guest Access Disabled By Default In Windows 10 for SMB2 protocol

Jordan Ostreff -

In Windows 10 after version 1709, Windows Server also after version 1709, the SMB2 client no longer allows the following actions:

  • Guest account access to a remote server
  • Fallback to the Guest account after invalid credentials are provided

SMBv2 has the following behavior in these versions of Windows:

  • Windows 10 Enterprise and Windows 10 Education no longer allow a user to connect to a remote share by using guest credentials by default, even if the remote server requests guest credentials.
  • Windows Server 2016 Datacenter and Standard edition no longer allow a user to connect to a remote share by using guest credentials by default, even if the remote server requests guest credentials.
  • Windows 10 Home and Professional editions are unchanged from their previous default behavior.

Solution 1

Re-Enable the guest account fallback - Microsoft are updating his manual periodically. In general idea is

  1. Go into Local Group Policy Editor
  2. Navigate into Administrative Templates - Network - Lanman Workstation.
  3. Then the Setting : Enable insecure guest logons has to be set to "Enable".
  4. Enable : Allow guest usage and solve the problem
  5. Disable : Will not allow guest usage and provide this problem.

Solution 2

Change the Samba "map to guest" parameter into configuration file ( smb.conf or smb4.conf ). Standard setting by default is "map to guest = bad user". This setting sets a guest session flag during initial SMB tree connect, and the listed Windows versions can end up failing to establish a session.

When changed to "map to guest = Never", then instead of silently dropping the connection, the Windows client prompts for a password.

  • reload Samba : service smb restart