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Microsoft has released Windows 11 Insider Preview Build 25992 to Windows Insiders in the Canary channel.





Announcing Windows 11 Insider Preview Build 25992 (Canary Channel)

Hello Windows Insiders, today we are releasing Windows 11 Insider Preview Build 25992 to the Canary Channel. 

What’s new in Build 25992

SMB Changes

Starting with this build (Build 25992), we are introducing the following Server Message Block (SMB) protocol changes.

SMB firewall rule changes: Creating SMB shares changes a longtime Windows Defender Firewall default behavior. Previously, creating a share automatically configured the firewall to enable the rules in the “File and Printer Sharing” group for the given firewall profiles. Now, Windows automatically configures the new “File and Printer Sharing (Restrictive)” group, which no longer contains inbound NetBIOS ports 137-139. We plan future updates for this rule to also remove inbound ICMP, LLMNR, and Spooler Service ports and restrict down to the SMB sharing-necessary ports only.

This change enforces a higher degree of default of network security as well as bringing SMB firewall rules closer to the Windows Server “File Server” role behavior. Administrators can still configure the “File and Printer Sharing” group if necessary as well as modify this new firewall group.

For more information on this change, review  https://aka.ms/SMBfirewall. For more information on SMB network security, review  Secure SMB Traffic in Windows Server.

SMB NTLM blocking exception list: The new SMB NTLM blocking feature first announced in Windows 11 Insider Preview Build 25951 now supports specifying exception lists for NTLM usage. This allows an administrator to configure a general block on NTLM usage while still allowing clients to use NTLM for specific servers that do not support Kerberos, either because they are not Active Directory domain joined or are a third party without Kerberos support.

For more information on this change, review  https://aka.ms/SmbNtlmBlock.

SMB alternative client and server ports: The SMB client now supports connecting to an SMB server over TCP, QUIC, or RDMA using alternative network ports to the hardcoded defaults. Previously, SMB only supported TCP/445, QUIC/443, and RDMA iWARP/5445. In addition, the SMB over QUIC server in Windows Server also supports endpoints configured with different ports than 443 (this option will be part of a separate Windows Server Insider Preview release). Windows Server does not support configuring alternative SMB server TCP ports, but third parties such as Samba do.

You can specify an alternative SMB client port using the NET USE command and New-SmbMapping PowerShell cmdlet. You can also completely disable this feature with a group policy.

For more information on using this option, review  https://aka.ms/SMBAlternativePorts. For more information on configuring non-standard SMB server ports in third parties, consult their product documentation.

SMB over QUIC client access control certificate changes: The SMB over QUIC client access control feature first announced in Windows 11 Insider Preview Build 25977 now supports using certificates with subject alternative names and not just a single subject. This means the client access control feature now supports using a Microsoft AD Certificate Authority and multiple endpoint names, just like the currently released version of SMB over QUIC. You can now evaluate the feature using the recommended options and not require self-signed test certificates.

For more information on this change, review  https://aka.ms/SmbOverQUICCAC. For more information on SMB over QUIC, review  https://aka.ms/SMBoverQUIC.


Announcing Windows 11 Insider Preview Build 25992 (Canary Channel)