[PATCH] param: disable print notify backchannel by default

Andrew Bartlett abartlet at samba.org
Wed Oct 16 13:56:02 MDT 2013

On Tue, 2013-10-15 at 12:05 +0200, David Disseldorp wrote:
> On Mon, 14 Oct 2013 13:53:22 +0200
> David Disseldorp <ddiss at samba.org> wrote:
> > In handling RemoteFindFirstPrinterChangeNotifyEx requests, the spoolss
> > server can establish a "backchannel" connection to the print client, as
> > a mechanism for sending print notifications. This behaviour is governed
> > by the "print notify backchannel" smb.conf parameter.
> > 
> > This change sets "print notify backchannel" to "no" by default, which
> > sees Samba respond to RemoteFindFirstPrinterChangeNotifyEx requests with
> > WERR_SERVER_UNAVAILABLE. In recieving such a response, print clients can
> > fall back to polling for print queue changes.
> For the record, I expect print clients since Windows Vista have not
> accepted back-channel connections without manual registry changes:
> https://blogs.technet.com/b/askperf/archive/2009/01/16/understanding-print-notifications-in-windows-vista.aspx?Redirected=true

Thanks for that confirmation.  Do you think we should put mention of
this in the manpage?  (Or at least mention it in WHATSNEW when
explaining the changed default). 

Andrew Bartlett

Andrew Bartlett
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Catalyst IT                   http://catalyst.net.nz

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