This setting controls the minimum protocol version that the client will attempt to use. Normally this option should not be set as the automatic negotiation phase in the SMB protocol takes care of choosing the appropriate protocol unless you connect to a legacy SMB1-only server. See client max protocol for a full list of available protocols. IPC$ connections for DCERPC e.g. in winbindd, are handled by the option. Note that most command line tools support --option='client min protocol=NT1', so it may not be required to enable SMB1 protocols globally in smb.conf. client max protocol server min protocol client ipc min protocol client ipc max protocol SMB2_02 NT1