[BackupPC-users] Backing up Windows shares.

[G.W. H. <ba...@ju...>]

Hi there,

For many years BackupPC has offered the option of using using Samba's
smbclient to back up Windows SMB shares.

Unfortunately it seems that in this use case there are multiple issues
with smbclient, see for example from January 2019:

https://github.com/backuppc/backuppc/issues/252

Windows junctions can make it impossible to exclude things you want to
exclude; one particular problem with smbclient is that excludes don't
seem to work properly, and haven't done for some time.

The 'regex' option for smbclient's tarmode is (a) broken since about
Samba 4.13, five years or more ago, and (b) deprecated in any case by
the Samba team since Samba 4.2 was released in March 2015 - so I don't
know if the option is ever likely to be fixed; one day it might simply
disappear.  Although Samba is very actively developed, a regression
reported on the Samba bugzilla in November 2022:

https://bugzilla.samba.org/show_bug.cgi?id=15229

has generated no response.  That may be because the 'r' option is, as
noted, now deprecated by Samba.  A 'wontfix' would have helped, but I
suspect that the lack of response from BackupPC developers to queries
in the past by Samba team members might figure to some extent in the
equation.  For the avoidance of doubt, I'm now the BackupPC maintainer
and I want somehow to get this fixed for Windows users.

So I got to wondering if anyone here is using CIFS to mount Windows 10
or Windows 11 SMB shares for BackupPC to read?  I'm sure it's possible
(apparently a lot of people using older NAS devices do it) but I don't
personally know anyone who's doing it.  It needs some administration
to get it working because it's not enabled by default in later Windows
versions, largely I think because of the potential security issues.

It seems to me that even though like anything else CIFS has security
issues, CIFS access could be restricted to the BackupPC server which
should eliminate the vast majority.  Using a remote mount would allow
BackupPC to use tar instead of smbclient, thus eliminating the problem
with excludes and potentially a bunch of other issues using smbclient.

Yet another alternative might be to use a different SMB client, but I
know nothing about such clients except that at least one exists.  This
would probably require quite a lot of development in BackupPC which to
me makes it an unlikely candidate at least in the near term (i.e. the
next few years) unless someone here wants to step up and do the work.

Comments welcome.  I can't test on anything more recent than a Win7 VM
which I have kicking around from the days - sorry, years - when I
supported Windows installations, thankfully now long past.

-- 

73,
Ged.