This is a new feature introduced with Samba 3.2 and above. It is an extension to the SMB/CIFS protocol negotiated as part of the UNIX extensions. SMB encryption uses the GSSAPI (SSPI on Windows) ability to encrypt and sign every request/response in a SMB protocol stream. When enabled it provides a secure method of SMB/CIFS communication, similar to an ssh protected session, but using SMB/CIFS authentication to negotiate encryption and signing keys. Currently this is only supported by Samba 3.2 smbclient, and hopefully soon Linux CIFSFS and MacOS/X clients. Windows clients do not support this feature. This controls whether the server offers or requires the client it talks to to use SMB encryption. Possible values are auto, mandatory and disabled. This may be set on a per-share basis, but clients may chose to encrypt the entire session, not just traffic to a specific share. If this is set to mandatory then all traffic to a share must must be encrypted once the connection has been made to the share. The server would return "access denied" to all non-encrypted requests on such a share. Selecting encrypted traffic reduces throughput as smaller packet sizes must be used (no huge UNIX style read/writes allowed) as well as the overhead of encrypting and signing all the data. If SMB encryption is selected, Windows style SMB signing (see the option) is no longer necessary, as the GSSAPI flags use select both signing and sealing of the data. When set to auto, SMB encryption is offered, but not enforced. When set to mandatory, SMB encryption is required and if set to disabled, SMB encryption can not be negotiated. auto