16.1. Configuring Samba Share Access Controls

This section deals with how to configure Samba per share access control restrictions. By default samba sets no restrictions on the share itself. Restrictions on the share itself can be set on MS Windows NT4/200x/XP shares. This can be a very effective way to limit who can connect to a share. In the absence of specific restrictions the default setting is to allow the global user Everyone Full Control (ie: Full control, Change and Read).

At this time Samba does NOT provide a tool for configuring access control setting on the Share itself. Samba does have the capacity to store and act on access control settings, but the only way to create those settings is to use either the NT4 Server Manager or the Windows 200x MMC for Computer Management.

Samba stores the per share access control settings in a file called share_info.tdb. The location of this file on your system will depend on how samba was compiled. The default location for samba's tdb files is under /usr/local/samba/var. If the tdbdump utility has been compiled and installed on your system then you can examine the contents of this file by: tdbdump share_info.tdb.

16.1.1. Share Permissions Management

The best tool for the task is platform dependant. Choose the best tool for your environmemt.

16.1.1.1. Windows NT4 Workstation/Server

The tool you need to use to manage share permissions on a Samba server is the NT Server Manager. Server Manager is shipped with Windows NT4 Server products but not with Windows NT4 Workstation. You can obtain the NT Server Manager for MS Windows NT4 Workstation from Microsoft - see details below.

Instructions

1. Launch the NT4 Server Manager, click on the Samba server you want to administer, then from the menu select Computer, then click on the Shared Directories entry.

2. Now click on the share that you wish to manage, then click on the Properties tab, next click on the Permissions tab. Now you can Add or change access control settings as you wish.

16.1.1.2. Windows 200x/XP

On MS Windows NT4/200x/XP system access control lists on the share itself are set using native tools, usually from filemanager. For example, in Windows 200x: right click on the shared folder, then select 'Sharing', then click on 'Permissions'. The default Windows NT4/200x permission allows Everyone Full Control on the Share.

MS Windows 200x and later all comes with a tool called the 'Computer Management' snap-in for the Microsoft Management Console (MMC). This tool is located by clicking on Control Panel -> Administrative Tools -> Computer Management.

Instructions

1. After launching the MMC with the Computer Management snap-in, click on the menu item 'Action', select 'Connect to another computer'. If you are not logged onto a domain you will be prompted to enter a domain login user identifier and a password. This will authenticate you to the domain. If you where already logged in with administrative privilidge this step is not offered.

2. If the Samba server is not shown in the Select Computer box, then type in the name of the target Samba server in the field 'Name:'. Now click on the [+] next to 'System Tools', then on the [+] next to 'Shared Folders' in the left panel.

3. Now in the right panel, double-click on the share you wish to set access control permissions on. Then click on the tab 'Share Permissions'. It is now possible to add access control entities to the shared folder. Do NOT forget to set what type of access (full control, change, read) you wish to assign for each entry.

Be careful. If you take away all permissions from the Everyone user without removing this user then effectively no user will be able to access the share. This is a result of what is known as ACL precidence. ie: Everyone with NO ACCESS means that MaryK who is part of the group Everyone will have no access even if this user is given explicit full control access.

16.2. Remote Server Administration

How do I get 'User Manager' and 'Server Manager'?

Since I don't need to buy an NT4 Server, how do I get the 'User Manager for Domains', the 'Server Manager'?

Microsoft distributes a version of these tools called nexus for installation on Windows 9x / Me systems. The tools set includes:

• Server Manager

• User Manager for Domains

• Event Viewer

Click here to download the archived file ftp://ftp.microsoft.com/Softlib/MSLFILES/NEXUS.EXE

The Windows NT 4.0 version of the 'User Manager for Domains' and 'Server Manager' are available from Microsoft via ftp from ftp://ftp.microsoft.com/Softlib/MSLFILES/SRVTOOLS.EXE

16.3. Network Logon Script Magic

This section needs work. Volunteer contributions most welcome. Please send your patches or updates to John Terpstra.

There are several opportunities for creating a custom network startup configuration environment.

The Samba source code tree includes two logon script generation/execution tools. See examples directory genlogon and ntlogon subdirectories.

The following listings are from the genlogon directory.

This is the genlogon.pl file:

	#!/usr/bin/perl
	#
	# genlogon.pl
	#
	# Perl script to generate user logon scripts on the fly, when users
	# connect from a Windows client.  This script should be called from smb.conf
	# with the %U, %G and %L parameters. I.e:
	#
	#       root preexec = genlogon.pl %U %G %L
	#
	# The script generated will perform
	# the following:
	#
	# 1. Log the user connection to /var/log/samba/netlogon.log
	# 2. Set the PC's time to the Linux server time (which is maintained
	#    daily to the National Institute of Standard's Atomic clock on the
	#    internet.
	# 3. Connect the user's home drive to H: (H for Home).
	# 4. Connect common drives that everyone uses.
	# 5. Connect group-specific drives for certain user groups.
	# 6. Connect user-specific drives for certain users.
	# 7. Connect network printers.

	# Log client connection
	#($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
	($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
	open LOG, ">>/var/log/samba/netlogon.log";
	print LOG "$mon/$mday/$year $hour:$min:$sec - User $ARGV[0] logged into $ARGV[1]\n";
	close LOG;

	# Start generating logon script
	open LOGON, ">/shared/netlogon/$ARGV[0].bat";
	print LOGON "\@ECHO OFF\r\n";

	# Connect shares just use by Software Development group
	if ($ARGV[1] eq "SOFTDEV" || $ARGV[0] eq "softdev")
	{
		print LOGON "NET USE M: \\\\$ARGV[2]\\SOURCE\r\n";
	}

	# Connect shares just use by Technical Support staff
	if ($ARGV[1] eq "SUPPORT" || $ARGV[0] eq "support")
	{
		print LOGON "NET USE S: \\\\$ARGV[2]\\SUPPORT\r\n";
	}

	# Connect shares just used by Administration staff
	If ($ARGV[1] eq "ADMIN" || $ARGV[0] eq "admin")
	{
		print LOGON "NET USE L: \\\\$ARGV[2]\\ADMIN\r\n";
		print LOGON "NET USE K: \\\\$ARGV[2]\\MKTING\r\n";
	}

	# Now connect Printers.  We handle just two or three users a little
	# differently, because they are the exceptions that have desktop
	# printers on LPT1: - all other user's go to the LaserJet on the
	# server.
	if ($ARGV[0] eq 'jim'
	    || $ARGV[0] eq 'yvonne')
	{
		print LOGON "NET USE LPT2: \\\\$ARGV[2]\\LJET3\r\n";
		print LOGON "NET USE LPT3: \\\\$ARGV[2]\\FAXQ\r\n";
	}
	else
	{
		print LOGON "NET USE LPT1: \\\\$ARGV[2]\\LJET3\r\n";
		print LOGON "NET USE LPT3: \\\\$ARGV[2]\\FAXQ\r\n";
	}

	# All done! Close the output file.
	close LOGON;

Those wishing to use more elaborate or capable logon processing system should check out the following sites: