SMB Min Protocol = SMB2 Not Working on Debian/Ubuntu

Mindwatering Incorporated

Author: Tripp W Black

Created: 07/26/2017 at 12:52 PM

 

Category:
Ubuntu
SMB

Issue:
SMB access broken on Ubuntu and flaky on Mac to Ubuntu Samba target shares after addition of : client min protocol = SMB2.

When trying the share from Ubuntu 14 and 16 linux, the immediate response back is a "connection timed out" message. Running the client command:
$ sudo smbclient -U myuserid -L myserveripordns
The response is:
protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE

Connections from Mac OSX 10.11 and 10.12 both work but load is slow.
The connections are also being dropped. (We have client accessing of shares that stay active for months just fine in the past.)

We tried updating the /etc/samba/smb.conf with:
min protocol = SMB2
server min protocol = SMB2 (alias for min protocol)
client min protocol = SMB2

Testparm showed no issues, but none of the 3 worked. Same message from the smbclient program:
protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE

and we tried it with the following protocol settings:
min protocol = SMB2
max protocol = SMB3

Testparm showed no issues, but this didn't work either. Same message from the smbclient program:
protocol negotiation failed: NT_STATUS_INVALID_NETWORK_RESPONSE


Workaround:
Since our lone MS Windows VM client supports SMB3, we decided to to try only the SMB 3 protocol with protocol = SMB3, and remove the min protocol = SMB2 and max protocol = SMB3 settings.

So we removed both the min and max lines, added to the smb.conf file:
protocol = SMB3

We ran testparm with success again. We restarted the smbd services
$ sudo service smbd restart

We logged back into the services again. Success:
- The Mac access was still a little slower to load than before we started updating any protocol settings, but still displaying in less than 1 to 2 seconds.
- The Ubuntu access was now finally working with about the same load time of 1 to 2 seconds.
- The MS Windows VM was also working, with slower than before load time of 2 to 4 seconds. Good enough.

It appears it loads SMB3 as SMB3_00 which according to the Samba docs, appears to be what's supposed to happen.




previous page