Administrative rights are necessary in two specific forms:

Administrative tasks on UNIX/Linux systems, such as adding users or groups, requires root level privilege. The addition of a Windows client to a Samba Domain involves the addition of a user account for the Windows client.

Many UNIX administrators continue to request the Samba Team make it possible to add Windows workstations, or to ability to add/delete or modify user accounts, without requiring root privileges. Such a request violates every understanding of basic UNIX system security.

There is no safe way to provide access on a UNIX/Linux system without providing root level privilege. Provision of root privileges can be done either by logging onto the Domain as the user root, or by permitting particular users to use a UNIX account that is a member of the UNIX group that has a GID=0 as the primary group in the /etc/passwd database. Users of such accounts can use tools like the NT4 Domain User Manager, and the NT4 Domain Server Manager to manage user and group accounts as well as Domain Member server and client accounts. This level of privilege is also needed to manage share level ACLs.

Administrative tasks on a Windows Domain Member workstation, can be done by anyone who is a member of the Domain Admins group. This group can be mapped to any convenient UNIX group.

When first installed, Microsoft Windows NT4/200x/XP are pre-configured with certain User, Group, and Alias entities. Each has a well-known Relative Identifier (RID). These must be preserved for continued integrity of operation. Samba must be provisioned with certain essential Domain Groups that require the appropriate RID value. When Samba-3 is configured to use tdbsam the essential Domain Groups are automatically created. It is the LDAP administrators' responsibility to create (provision) the default NT Groups.

Each essential Domain Group must be assigned its respective well-known RID. The default Users, Groups, Aliases, and RIDs are shown in Well-Known User Default RIDs table.

It is permissible to create any Domain Group that may be necessary, just make certain that the essential Domain Groups (well known) have been created and assigned its default RID. Other groups you create may be assigned any arbitrary RID you care to use.

Be sure to map each Domain Group to a UNIX system group. That is the only way to ensure that the group will be available for use as an NT Domain Group.

You can list the various groups in the mapping database by executing net groupmap list. Here is an example:

root#  net groupmap list
Domain Admins (S-1-5-21-2547222302-1596225915-2414751004-512) -> domadmin
Domain Users (S-1-5-21-2547222302-1596225915-2414751004-513) -> domuser
Domain Guests (S-1-5-21-2547222302-1596225915-2414751004-514) -> domguest

For complete details on net groupmap, refer to the net(8) man page.

A script to create complying group names for use by the Samba group interfaces is provided in smbgrpadd.sh.

#!/bin/bash

# Add the group using normal system groupadd tool.
groupadd smbtmpgrp00

thegid=`cat /etc/group | grep ^smbtmpgrp00 | cut -d ":" -f3`

# Now change the name to what we want for the MS Windows networking end
cp /etc/group /etc/group.bak
cat /etc/group.bak | sed "s/^smbtmpgrp00/$1/g" > /etc/group

# Now return the GID as would normally happen.
echo $thegid
exit 0

The smb.conf entry for the above script would be something like that in the following example.

In our example we have created a UNIX/Linux group called ntadmin. Our script will create the additional groups Orks, Elves, and Gnomes. It is a good idea to save this shell script for later re-use just in case you ever need to rebuild your mapping database. For the sake of convenience we elect to save this script as a file called initGroups.sh. This script is given in intGroups.sh.

#!/bin/bash

net groupmap modify ntgroup="Domain Admins" unixgroup=ntadmin
net groupmap modify ntgroup="Domain Users" unixgroup=users
net groupmap modify ntgroup="Domain Guests" unixgroup=nobody

groupadd Orks
groupadd Elves
groupadd Gnomes

net groupmap add ntgroup="Orks"   unixgroup=Orks   type=d
net groupmap add ntgroup="Elves"  unixgroup=Elves  type=d
net groupmap add ntgroup="Gnomes" unixgroup=Gnomes type=d

Of course it is expected that the administrator will modify this to suit local needs. For information regarding the use of the net groupmap tool please refer to the man page.

This is a common problem when the groupadd is called directly by the Samba interface script for the add group script in the smb.conf file.

The most common cause of failure is an attempt to add an MS Windows group account that has either an upper case character and/or a space character in it.

There are three possible work-arounds. First, use only group names that comply with the limitations of the UNIX/Linux groupadd system tool. Second, it involves the use of the script mentioned earlier in this chapter, and third is the option is to manually create a UNIX/Linux group account that can substitute for the MS Windows group name, then use the procedure listed above to map that group to the MS Windows group.

Samba-3 does not support nested groups from the MS Windows control environment.

“ What must I do to add Domain Users to the Power Users group? ”

The Power Users group is a group that is local to each Windows 200x/XP Professional workstation. You cannot add the Domain Users group to the Power Users group automatically, it must be done on each workstation by logging in as the local workstation administrator and then using the following procedure: