SMB Dialect Issue

[phab_lucky]

I developed a custom CIFS server some time back using JLAN embedded and everything was working great. After a couple of months without using it, I tried to connect from the same Windows 7 Pro machine used in development and got the following error message on the server's console:

[T10] Failed to negotiate SMB dialect

I debugged the negotiation process and found out that my client is sending the following dialect strings:

NotSmb,NotSmb,NotSmb,NotSmb,NotSmb,NotSmb,SMB 2.002,SMB 2.???

On the other hand, the server's supported dialects are:

[DOS LANMAN 1.0,LANMAN1.0,DOS LANMAN 2.1,LM1.2X002,LANMAN2.1,NT LM 0.12]

I don't understand why this stopped working after a couple of months and don't know which dialects my client was reporting earlier. Does anyone know what might have happened here?

Regards.

[afaust]

Microsoft may have disabled the old (obsolete) SMB dialect that JLAN supports via an update. This was announced for Windows 10 sometime this year and may also have been planned/executed for WIndows 7 (I no longer follow updates for Windows 7).

[phab_lucky]

Really?? I suspected of something like that and tried to enable SMB1 via sc.exe command, but nothing happened. Any clue on how to keep this working? Any hope that JLAN will support the more modern dialects?

[afaust]

JLAN is a defunct project (there has not been any release since 2009) and is currently only maintained as an embedded library of Alfresco Content Services. In your place I would have higher hopes for hell freezing over than JLAN standalone supporting newer SMB dialects.

The community has besieged Alfresco for years to consider supporting newer SMB dialect versions. The announcement by Microsoft has sparked renewed dialogue within this platform, and at least an epic now exists in Alfresco JIRA for potential consideration in future development. Even if Alfresco decides to implement SMB 3 there is no guarantee that it will be available in the Open Source version. Alfresco is looking to have technical differentiators to support their business model for the commercial version, and since WebDAV can be used to mount Alfresco as a drive, a vast majority of users of the Community Edition may not have the need to have SMB 3 available to them. The typical rule of thumb is that any feature that a majority of customers / end-users are going to need in some form will be considered for the Open Source version, while features that only benefit a small number of special, big Enterprise-like use cases will likely be reserved for the commercial version.

[phab_lucky]

Thank you for the insightful reply. In any case, I have this issue that I need to address in the near term. Could you provide me any porinters on how to undo whatever change this Windows update has caused to my system?

Much appreciated.

[afaust]

Since I don't know what the update may have done / what specifically is blocking SMBv1 from working in your case, and I don't have a Windows 7 system at hand at all, I cannot give you any pointers. Everything I could give you are just links to the same pages you'll find via Google. I would start with checking if the Windows feature for SMBv1 support is still enabled via Control Panel -> Programs and Features

[phab_lucky]

For the sake of documenting the solution, I solved the problem by re-enabling SMB1 following these instructions:

https://support.microsoft.com/pt-br/help/2696547/how-to-enable-and-disable-smbv1-smbv2-and-smbv3-in-... 

I'll start looking at WebDAV alternatives to CIFS right away.

Thanks again for your support.