Disable SMBv1 on an SMB server
The `SMB1` value is a `REG_DWORD` that controls the computer's SMBv1 server component.
since 0.9.8.11
Purpose
Show registry keys (1)
HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\SMB1
The SMB1 value is a REG_DWORD that controls the computer's SMBv1 server component. A value of 0 disables that component. Consequently, the computer no longer accepts inbound file-sharing connections that rely exclusively on the legacy SMBv1 protocol.
This setting applies only to the server side. It does not disable the SMBv1 client for outbound connections, nor does it disable the SMBv2 or SMBv3 server protocols.
Notes
Security
Disabling the SMBv1 server component reduces the attack surface exposed through SMB. SMBv1 has known security vulnerabilities and lacks several protections available in newer SMB versions, including the preauthentication integrity and encryption capabilities provided by SMB 3.
This setting does not eliminate SMBv1 completely from the system: an installed SMBv1 client component remains unaffected. It also does not impose signing or encryption requirements on SMBv2 or SMBv3 connections.
Possible side effects
Legacy computers, devices, or applications that support only SMBv1 can no longer access SMB shares hosted by this computer. On domain controllers, this can also affect systems that require access to SYSVOL or other shares but do not support SMBv2 or SMBv3.
Connections using SMBv2 or SMBv3 remain available when those protocols are present and enabled.
Notes
This setting disables the SMBv1 server component but does not uninstall the Windows “SMB 1.0/CIFS File Sharing Support” feature. A computer restart is required after changing this registry value.
SMBv1 is not installed by default on clean installations of Windows 11 or Windows Server 2019 and later. If the server component is absent, disabling it through this value has no additional practical effect.
Microsoft documentation
Microsoft Learn: Detect, enable, and disable SMBv1, SMBv2, and SMBv3 in Windows
Microsoft Learn: Protect SMB traffic from interception