Force Mac SMB server to use SMB version 3.1.1

I have a Mac mini acting as a SMB server for both Mac and Windows 11 clients. smbutil shows that the connections to the server are using smb version 3.0.2. There is a Linux server on the network that is also a smb server. Connections to this server report as version 3.1.1. I would like connections to the Mac smb server to also use version 3.1.1. However, I cannot find any directions on how to do it.

Mac mini (2018)

Posted on Oct 11, 2023 5:10 PM

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6 replies

Nov 3, 2023 8:09 AM in response to Clayton Leitch

We have the opposite problem. Our Mac Sonoma 14.1 users cannot establish an SMB connection to the institutional SAN, as the institution's SANM does not support higher than SMB 3.0. We assume Sonoma is trying SMB 3.1.1.


Our Windows 11 users had the same problem, but there's a Window Registry that allows you to set the maximum negotiated SMB version — in this case from SMB 3.1.1 to SMB 3.0. And with that Registry entry, the Windows 11 SMB clients have no problem connecting to the institution's NAS.


Unfortunately, there is no corresponding MaxNegotiatedSMB setting in MacOS' /etc/nsmb.conf file.


Furthermore, there appears to be no way in MacOS Sonama's /etc/nsmb.conf file to limit SMB version to SMB v2.


In other *nix implementations, protocol_vers_map= can have arguments of 1, 2, & 3, corresponding to SMB 1, SMB 2, SMB 1/2.


But the MacOS 14.1 man pages for the nsmb.conf entry protocol_vers_map=, list only 4, 5, & 6, corresponding to SMB 3, SMB 2/3, & SMB 1/2/3 as valid arguments. And this seems to be deliberate, because any of:

protocol_vers_map=1

protocol_vers_map=2

protocol_vers_map=3

seem to have no effect if entered into MacOS 14.1's /etc/nsmb.conf file.

Force Mac SMB server to use SMB version 3.1.1

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