Printing Support in Samba 2.2.x


Introduction

Beginning with the 2.2.0 release, Samba supports the native Windows NT printing mechanisms implemented via MS-RPC (i.e. the SPOOLSS named pipe). Previous versions of Samba only supported LanMan printing calls.

The additional functionality provided by the new SPOOLSS support includes:


Configuration

In order to support the uploading of printer driver files, you must first configure a file share named [print$]. The name of this share is hard coded in Samba's internals so the name is very important (print$ is the service used by Windows NT print servers to provide support for printer driver download).

Warning

Previous versions of Samba recommended using a share named [printer$]. This name was taken from the printer$ service created by Windows 9x clients when a printer was shared. Windows 9x printer servers always have a printer$ service which provides read-only access via no password in order to support printer driver downloads.

However, the initial implementation allowed for a parameter named printer driver location to be used on a per share basis to specify the location of the driver files associated with that printer. Another parameter named printer driver provided a means of defining the printer driver name to be sent to the client.

These parameters, including printer driver file parameter, are being depreciated and should not be used in new installations. For more information on this change, you should refer to the Migration section of this document.

You should modify the server's smb.conf file to create the following file share (of course, some of the parameter values, such as 'path' are arbitrary and should be replaced with appropriate values for your site):

[print$]
	path = /usr/local/samba/printers
	guest ok = yes
	browseable = yes
	read only = yes
	write list = ntadmin
	

The write list is used to allow administrative level user accounts to have write access in order to update files on the share. See the smb.conf(5) man page for more information on configuring file shares.

The requirement for guest ok = yes depends upon how your site is configured. If users will be guaranteed to have an account on the Samba host, then this is a non-issue.

author's note: The non-issue is that if all your Windows NT users are guarenteed to be authenticated by the Samba server (such as a domain member server and the NT user has already been validated by the Domain Controller in order to logon to the Windows NT console), then guest access is not necessary. Of course, in a workgroup environment where you just want to be able to print without worrying about silly accounts and security, then configure the share for guest access. You'll probably want to add map to guest = Bad User in the [global] section as well. Make sure you understand what this parameter does before using it though. --jerry]

In order for a Windows NT print server to support the downloading of driver files by multiple client architectures, it must create subdirectories within the [print$] service which correspond to each of the supported client architectures. Samba follows this model as well.

Next create the directory tree below the [print$] share for each architecture you wish to support.

	[print$]-----
		|-W32X86		; "Windows NT x86"
		|-WIN40			; "Windows 95/98"
		|-W32ALPHA		; "Windows NT Alpha_AXP"
		|-W32MIPS		; "Windows NT R4000"
		|-W32PPC		; "Windows NT PowerPC"
	

Warning

ATTENTION! REQUIRED PERMISSIONS

In order to currently add a new driver to you Samba host, one of two conditions must hold true:

  • The account used to connect to the Samba host must have a uid of 0 (i.e. a root account)

  • The account used to connect to the Samba host must be a member of the printer admin list.

Of course, the connected account must still possess access to add files to the subdirectories beneath [print$].

Once you have created the required [print$] service and associated subdirectories, simply log onto the Samba server using a root (or printer admin) account from a Windows NT 4.0 client. Navigate to the "Printers" folder on the Samba server. You should see an initial listing of printers that matches the printer shares defined on your Samba host.

The initial listing of printers in the Samba host's Printers folder will have no printer driver assigned to them. The way assign a driver to a printer is to view the Properties of the printer and either

If you wish to install printer drivers for client operating systems other than "Windows NT x86", you will need to use the "Sharing" tab of the printer properties dialog.

Assuming you have connected with a root account, you will also be able modify other printer properties such as ACLs and device settings using this dialog box.

A few closing comments for this section, it is possible on a Windows NT print server to have printers listed in the Printers folder which are not shared. Samba does not make this distinction. By definition, the only printers of which Samba is aware are those which are specified as shares in smb.conf.

Another interesting side note is that Windows NT clients do not use the SMB printer share, but rather can print directly to any printer on another Windows NT host using MS-RPC. This of course assumes that the printing client has the necessary privileges on the remote host serving the printer. The default permissions assigned by Windows NT to a printer gives the "Print" permissions to the "Everyone" well-known group.


Support a large number of printers

One issue that has arisen during the development phase of Samba 2.2 is the need to support driver downloads for 100's of printers. Using the Windows NT APW is somewhat awkward to say the list. If more than one printer are using the same driver, the rpcclient's setdriver command can be used to set the driver associated with an installed driver. The following is example of how this could be accomplished:

 
		$ rpcclient pogo -U root%secret -c "enumdrivers"
Domain=[NARNIA] OS=[Unix] Server=[Samba 2.2.0-alpha3]
 
[Windows NT x86]
Printer Driver Info 1:
	Driver Name: [HP LaserJet 4000 Series PS]
 
Printer Driver Info 1:
	Driver Name: [HP LaserJet 2100 Series PS]
 
Printer Driver Info 1:
	Driver Name: [HP LaserJet 4Si/4SiMX PS]
				  
		$ rpcclient pogo -U root%secret -c "enumprinters"
Domain=[NARNIA] OS=[Unix] Server=[Samba 2.2.0-alpha3]
	flags:[0x800000]
	name:[\\POGO\hp-print]
	description:[POGO\\POGO\hp-print,NO DRIVER AVAILABLE FOR THIS PRINTER,]
	comment:[]
				  
		$ rpcclient pogo -U root%bleaK.er \
		>  -c "setdriver hp-print \"HP LaserJet 4000 Series PS\""
Domain=[NARNIA] OS=[Unix] Server=[Samba 2.2.0-alpha3]
Succesfully set hp-print to driver HP LaserJet 4000 Series PS.
		


The Imprints Toolset

The Imprints tool set provides a UNIX equivalent of the Windows NT Add Printer Wizard. For complete information, please refer to the Imprints web site at http://imprints.sourceforge.net/ as well as the documentation included with the imprints source distribution. This section will only provide a brief introduction to the features of Imprints.


What is Imprints?

Imprints is a collection of tools for supporting the goals of

  • Providing a central repository information regarding Windows NT and 95/98 printer driver packages

  • Providing the tools necessary for creating the Imprints printer driver packages.

  • Providing an installation client which will obtain and install printer drivers on remote Samba and Windows NT 4 print servers.


Creating Printer Driver Packages

The process of creating printer driver packages is beyond the scope of this document (refer to Imprints.txt also included with the Samba distribution for more information). In short, an Imprints driver package is a gzipped tarball containing the driver files, related INF files, and a control file needed by the installation client.


The Imprints server

The Imprints server is really a database server that may be queried via standard HTTP mechanisms. Each printer entry in the database has an associated URL for the actual downloading of the package. Each package is digitally signed via GnuPG which can be used to verify that package downloaded is actually the one referred in the Imprints database. It is not recommended that this security check be disabled.


The Installation Client

More information regarding the Imprints installation client is available in the Imprints-Client-HOWTO.ps file included with the imprints source package.

The Imprints installation client comes in two forms.

  • a set of command line Perl scripts

  • a GTK+ based graphical interface to the command line perl scripts

The installation client (in both forms) provides a means of querying the Imprints database server for a matching list of known printer model names as well as a means to download and install the drivers on remote Samba and Windows NT print servers.

The basic installation process is in four steps and perl code is wrapped around smbclient and rpcclient.

	
		foreach (supported architecture for a given driver)
		{
			1.	rpcclient: Get the appropriate upload directory 
				on the remote server
			2.	smbclient: Upload the driver files
			3.	rpcclient: Issues an AddPrinterDriver() MS-RPC
		}
	
		4.	rpcclient: Issue an AddPrinterEx() MS-RPC to actually
			create the printer
		

One of the problems encountered when implementing the Imprints tool set was the name space issues between various supported client architectures. For example, Windows NT includes a driver named "Apple LaserWriter II NTX v51.8" and Windows 95 callsits version of this driver "Apple LaserWriter II NTX"

The problem is how to know what client drivers have been uploaded for a printer. As astute reader will remember that the Windows NT Printer Properties dialog only includes space for one printer driver name. A quick look in the Windows NT 4.0 system registry at

HKLM\System\CurrentControlSet\Control\Print\Environment

will reveal that Windows NT always uses the NT driver name. The is ok as Windows NT always requires that at least the Windows NT version of the printer driver is present. However, Samba does not have the requirement internally. Therefore, how can you use the NT driver name if is has not already been installed?

The way of sidestepping this limitation is to require that all Imprints printer driver packages include both the Intel Windows NT and 95/98 printer drivers and that NT driver is installed first.


Migration to from Samba 2.0.x to 2.2.x

Given that printer driver management has changed (we hope improved :) ) in 2.2.0 over prior releases, migration from an existing setup to 2.2.0 can follow several paths.

Warning

The following smb.conf parameters are considered to be depreciated and will be removed soon. Do not use them in new installations

  • printer driver file (G)

  • printer driver (S)

  • printer driver location (S)

Here are the possible scenarios for supporting migration: