[PATCH] change client max protocol default to PROTOCOL_LATEST

Alexander Bokovoy ab at samba.org
Fri May 26 12:04:22 UTC 2017

On pe, 26 touko 2017, Stefan Metzmacher via samba-technical wrote:
> Am 26.05.2017 um 11:33 schrieb Andrew Bartlett via samba-technical:
> > On Fri, 2017-05-26 at 12:14 +0300, Alexander Bokovoy via samba-
> > technical wrote:
> >> Hi,
> >>
> >> I'd like to start discussion to change 'client max protocol' default to
> >> always be PROTOCOL_LATEST instead of PROTOCOL_NT1. While there are known
> >> issues with this change for functionality only available over SMB1
> >> protocol version, we see increasing amount of deployments where Samba
> >> clients cannot in default configuration to connect to servers with
> >> disabled SMB1 protocol.
> >>
> >> Amount of systems with SMB1 support switched off is growing, especially
> >> after Microsoft Security Bulletin MS17-010 release (WannaCry). Many
> >> organizations did opt to disable SMB1 completely.
> >>
> >> At this point, I can think of two fall offs from this change:
> >>
> >>   - MS-RAP/MS-BRWS protocols will not work as they require SMB1
> >>   - POSIX extensions would not work as they require SMB1
> >>
> >> I'd like to see these two addressed in future, if possible. The former
> >> one probably would require an alternative approach so that GNOME and KDE
> >> UIs could still be able to display available shares and servers (Active
> >> Directory did disable browsing already so this is not a new issue). The
> >> latter one is in works as discussed during SambaXP.
> > 
> > Thanks Alexander for brining this up.  I was discussing the same with
> > Microsoft recently, and I think we have to find a practical way forward
> > here.  There is no point denying SMB2 access to servers that don't
> > support SMB1, and the majority of the servers supporting both SMB1 and
> > SMB2 won't support unix extensions in any case, yet we hold back the
> > protocol just in case.
> > 
> > Is there any way to detect that SMB1 unix extensions would have been
> > available while talking over SMB2?
> > 
> > It seems reasonable that we at least connect with SMB2 if SMB1 is not
> > available, and I would love to see us upgrade to SMB2 if unix
> > extensions were not available, ideally tested on a signed connection. 
> > 
> > Finally, I do hope we can get some progress on unix extensions.  The
> > world needs to be able to move on from SMB1, but this is really holding
> > things back. 
> I tried an autobuild with this change a few times in the past,
> but it sadly fails in a lot of places.
> I fear someone needs to actively work on this for a few days
> to get the existing tests working, in most cases we should test
> NT1 and SMB3 in order to avoid regressions.
> As much as I'd like to have this change, it's not that trivial
> as it seems.
Do we have a bug that could be used to track this work?

/ Alexander Bokovoy

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