This policy setting determines if the SMB client will allow insecure guest logons to an SMB server.
If you enable this policy setting or if you don't configure this policy setting, the SMB client will allow insecure guest logons.
If you disable this policy setting, the SMB client will reject insecure guest logons.
If you enable signing, the SMB client will reject insecure guest logons.
Insecure guest logons are used by file servers to allow unauthenticated access to shared folders. While uncommon in an enterprise environment, insecure guest logons are frequently used by consumer Network Attached Storage (NAS) appliances acting as file servers. Windows file servers require authentication and don't use insecure guest logons by default. Since insecure guest logons are unauthenticated, important security features such as SMB Signing and SMB Encryption are disabled. As a result, clients that allow insecure guest logons are vulnerable to a variety of man-in-the-middle attacks that can result in data loss, data corruption, and exposure to malware. Additionally, any data written to a file server using an insecure guest logon is potentially accessible to anyone on the network. Microsoft recommends disabling insecure guest logons and configuring file servers to require authenticated access".
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This article describes how to enable guest logons policy in SMB2 and SMB3 for Windows client and Windows Server devices using Group Policy and PowerShell.
Resolves an issue in which you can't access a shared folder through SMB2 protocol. This issue occurs in Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Server 2008 R2, Windows Vista, and Windows Server 2008.