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Table of Contents
The net command is one of the new features of Samba-3 and is an attempt to provide a useful tool for the majority of remote management operations necessary for common tasks. The net tool is flexible by design and is intended for command-line use as well as for scripted control application.
Originally introduced with the intent to mimic the Microsoft Windows command that has the same name, the net command has morphed into a very powerful instrument that has become an essential part of the Samba network administrator's toolbox. The Samba Team has introduced tools, such as smbgroupedit and rpcclient, from which really useful capabilities have been integrated into the net. The smbgroupedit command was absorbed entirely into the net, while only some features of the rpcclient command have been ported to it. Anyone who finds older references to these utilities and to the functionality they provided should look at the net command before searching elsewhere.
A Samba-3 administrator cannot afford to gloss over this chapter because to do so will almost certainly cause the infliction of self-induced pain, agony, and desperation. Be warned: this is an important chapter.
The tasks that follow the installation of a Samba-3 server, whether standalone or domain member, of a domain controller (PDC or BDC) begins with the need to create administrative rights. Of course, the creation of user and group accounts is essential for both a standalone server and a PDC. In the case of a BDC or a Domain Member server (DMS), domain user and group accounts are obtained from the central domain authentication backend.
Regardless of the type of server being installed, local UNIX groups must be mapped to the Windows networking domain global group accounts. Do you ask why? Because Samba always limits its access to the resources of the host server by way of traditional UNIX UID and GID controls. This means that local groups must be mapped to domain global groups so that domain users who are members of the domain global groups can be given access rights based on UIDs and GIDs local to the server that is hosting Samba. Such mappings are implemented using the net command.
UNIX systems that are hosting a Samba-3 server that is running as a member (PDC, BDC, or DMS) must have a machine security account in the domain authentication database (or directory). The creation of such security (or trust) accounts is also handled using the net command.
The establishment of interdomain trusts is achieved using the net command also, as may a plethora of typical administrative duties such as user management, group management, share and printer management, file and printer migration, security identifier management, and so on.
The overall picture should be clear now: the net command plays a central role on the Samba-3 stage. This role will continue to be developed. The inclusion of this chapter is evidence of its importance, one that has grown in complexity to the point that it is no longer considered prudent to cover its use fully in the online UNIX man pages.
The basic operations of the net command are documented here. This documentation is not
exhaustive, and thus it is incomplete. Since the primary focus is on migration from Windows servers to a Samba
server, the emphasis is on the use of the Distributed Computing Environment Remote Procedure Call (DCE RPC)
mode of operation. When used against a server that is a member of an Active Directory domain, it is preferable
(and often necessary) to use ADS mode operations. The net command supports both, but not
for every operation. For most operations, if the mode is not specified, net will
automatically fall back via the ads, rpc, and
rap modes. Please refer to the man page for a more comprehensive overview of the
capabilities of this utility.
As stated, the focus in most of this chapter is on use of the net rpc family of operations that are supported by Samba. Most of them are supported by the net ads mode when used in connection with Active Directory. The net rap operating mode is also supported for some of these operations. RAP protocols are used by IBM OS/2 and by several earlier SMB servers.
Samba's net tool implements sufficient capability to permit all common administrative tasks to be completed from the command line. In this section each of the essential user and group management facilities are explored.
Samba-3 recognizes two types of groups: domain groups and local groups. Domain groups can contain (have as members) only domain user accounts. Local groups can contain local users, domain users, and domain groups as members.
The purpose of a local group is to permit file permission to be set for a group account that, like the usual UNIX/Linux group, is persistent across redeployment of a Windows file server.
Samba provides file and print services to Windows clients. The file system resources it makes available to the Windows environment must, of necessity, be provided in a manner that is compatible with the Windows networking environment. UNIX groups are created and deleted as required to serve operational needs in the UNIX operating system and its file systems.
In order to make available to the Windows environment, Samba has a facility by which UNIX groups can be mapped to a logical entity, called a Windows (or domain) group. Samba supports two types of Windows groups, local and global. Global groups can contain as members, global users. This membership is affected in the normal UNIX manner, but adding UNIX users to UNIX groups. Windows user accounts consist of a mapping between a user SambaSAMAccount (logical entity) and a UNIX user account. Therefore, a UNIX user is mapped to a Windows user (i.e., is given a Windows user account and password) and the UNIX groups to which that user belongs, is mapped to a Windows group account. The result is that in the Windows account environment that user is also a member of the Windows group account by virtue of UNIX group memberships.
The following sub-sections that deal with management of Windows groups demonstrates the relationship between the UNIX group account and its members to the respective Windows group accounts. It goes on to show how UNIX group members automatically pass-through to Windows group membership as soon as a logical mapping has been created.
Before attempting to add a Windows group account, the currently available groups can be listed as shown here:
root# net rpc group list -Uroot%not24get
Password:
Domain Admins
Domain Users
Domain Guests
Print Operators
Backup Operators
Replicator
Domain Computers
Engineers
A Windows group account called “SupportEngrs” can be added by executing the following command:
root# net rpc group add "SupportEngrs" -Uroot%not24get
The addition will result in immediate availability of the new group account as validated by executing this command:
root# net rpc group list -Uroot%not24get
Password:
Domain Admins
Domain Users
Domain Guests
Print Operators
Backup Operators
Replicator
Domain Computers
Engineers
SupportEngrs
The following demonstrates that the POSIX (UNIX/Linux system account) group has been created by calling the add group script = /opt/IDEALX/sbin/smbldap-groupadd -p "%g" interface script:
root# getent group
...
Domain Admins:x:512:root
Domain Users:x:513:jht,lct,ajt,met
Domain Guests:x:514:
Print Operators:x:550:
Backup Operators:x:551:
Replicator:x:552:
Domain Computers:x:553:
Engineers:x:1002:jht
SupportEngrs:x:1003:
The following demonstrates that the use of the net command to add a group account results in immediate mapping of the POSIX group that has been created to the Windows group account as shown here:
root# net groupmap list
Domain Admins (S-1-5-21-72630-4128915-11681869-512) -> Domain Admins
Domain Users (S-1-5-21-72630-4128915-11681869-513) -> Domain Users
Domain Guests (S-1-5-21-72630-4128915-11681869-514) -> Domain Guests
Print Operators (S-1-5-21-72630-4128915-11681869-550) -> Print Operators
Backup Operators (S-1-5-21-72630-4128915-11681869-551) -> Backup Operators
Replicator (S-1-5-21-72630-4128915-11681869-552) -> Replicator
Domain Computers (S-1-5-21-72630-4128915-11681869-553) -> Domain Computers
Engineers (S-1-5-21-72630-4128915-11681869-3005) -> Engineers
SupportEngrs (S-1-5-21-72630-4128915-11681869-3007) -> SupportEngrs
Windows groups must be mapped to UNIX system (POSIX) groups so that file system access controls can be asserted in a manner that is consistent with the methods appropriate to the operating system that is hosting the Samba server.
All file system (file and directory) access controls, within the file system of a UNIX/Linux server that is hosting a Samba server, are implemented using a UID/GID identity tuple. Samba does not in any way override or replace UNIX file system semantics. Thus it is necessary that all Windows networking operations that access the file system provide a mechanism that maps a Windows user to a particular UNIX/Linux group account. The user account must also map to a locally known UID. Note that the net command does not call any RPC-functions here but directly accesses the passdb.
Samba depends on default mappings for the Domain Admins, Domain Users, and
Domain Guests global groups. Additional groups may be added as shown in the
examples just given. There are times when it is necessary to map an existing UNIX group account
to a Windows group. This operation, in effect, creates a Windows group account as a consequence
of creation of the mapping.
The operations that are permitted include: add, modify,
and delete. An example of each operation is shown here.
Commencing with Samba-3.0.23 Windows Domain Groups must be explicitly created. By default, all UNIX groups are exposed to Windows networking as Windows local groups.
An existing UNIX group may be mapped to an existing Windows group by this example:
root# net groupmap modify ntgroup="Domain Users" unixgroup=users
An existing UNIX group may be mapped to a new Windows group as shown here:
root# net groupmap add ntgroup="EliteEngrs" unixgroup=Engineers type=d
Supported mapping types are 'd' (domain global) and 'l' (domain local). A Windows group may be deleted, and then a new Windows group can be mapped to the UNIX group by executing these commands:
root#net groupmap delete ntgroup=Engineersroot#net groupmap add ntgroup=EngineDrivers unixgroup=Engineers type=d
The deletion and addition operations affected only the logical entities known as Windows groups, or domain groups. These operations are inert to UNIX system groups, meaning that they neither delete nor create UNIX system groups. The mapping of a UNIX group to a Windows group makes the UNIX group available as Windows groups so that files and folders on domain member clients (workstations and servers) can be given domain-wide access controls for domain users and groups.
Two types of Windows groups can be created: domain (global) and local.
In the previous examples the Windows groups created were of type domain or global. The
following command will create a Windows group of type local.
root# net groupmap add ntgroup=Pixies unixgroup=pixies type=l
Supported mapping types are 'd' (domain global) and 'l' (domain local), a domain local group in Samba is treated as local to the individual Samba server. Local groups can be used with Samba to enable multiple nested group support.
A group account may be deleted by executing the following command:
root# net rpc group delete SupportEngineers -Uroot%not24get
Validation of the deletion is advisable. The same commands may be executed as shown above.
This command is not documented in the man pages; it is implemented in the source code, but it does not work at this time. The example given documents, from the source code, how it should work. Watch the release notes of a future release to see when this may have been fixed.
Sometimes it is necessary to rename a group account. Good administrators know how painful some managers' demands can be if this simple request is ignored. The following command demonstrates how the Windows group “SupportEngrs” can be renamed to “CustomerSupport”:
root# net rpc group rename SupportEngrs \
CustomerSupport -Uroot%not24get
Three operations can be performed regarding group membership. It is possible to (1) add Windows users to a Windows group, to (2) delete Windows users from Windows groups, and to (3) list the Windows users that are members of a Windows group.
To avoid confusion, it makes sense to check group membership before attempting to make any changes.
The getent group will list UNIX/Linux group membership. UNIX/Linux group members are
seen also as members of a Windows group that has been mapped using the net groupmap
command (see ???). The following list of UNIX/Linux group membership shows
that the user ajt is a member of the UNIX/Linux group Engineers.
root# getent group
...
Domain Admins:x:512:root
Domain Users:x:513:jht,lct,ajt,met,vlendecke
Domain Guests:x:514:
Print Operators:x:550:
Backup Operators:x:551:
Replicator:x:552:
Domain Computers:x:553:
Engineers:x:1000:jht,ajt
The UNIX/Linux groups have been mapped to Windows groups, as is shown here:
root# net groupmap list
Domain Admins (S-1-5-21-72630-412605-116429-512) -> Domain Admins
Domain Users (S-1-5-21-72630-412605-116429-513) -> Domain Users
Domain Guests (S-1-5-21-72630-412605-116429-514) -> Domain Guests
Print Operators (S-1-5-21-72630-412605-116429-550) -> Print Operators
Backup Operators (S-1-5-21-72630-412605-116429-551) -> Backup Operators
Replicator (S-1-5-21-72630-412605-116429-552) -> Replicator
Domain Computers (S-1-5-21-72630-412605-116429-553) -> Domain Computers
Engineers (S-1-5-21-72630-412605-116429-3001) -> Engineers
Given that the user ajt is already a member of the UNIX/Linux group and, via the
group mapping, a member of the Windows group, an attempt to add this account again should fail. This is
demonstrated here:
root# net rpc group addmem "MIDEARTH\Engineers" ajt -Uroot%not24get
Could not add ajt to MIDEARTH\Engineers: NT_STATUS_MEMBER_IN_GROUP
This shows that the group mapping between UNIX/Linux groups and Windows groups is effective and transparent.
To permit the user ajt to be added using the net rpc group utility,
this account must first be removed. The removal and confirmation of its effect is shown here:
root#net rpc group delmem "MIDEARTH\Engineers" ajt -Uroot%not24getroot#getent group Engineers Engineers:x:1000:jhtroot#net rpc group members Engineers -Uroot%not24get MIDEARTH\jht
In this example both at the UNIX/Linux system level, the group no longer has the ajt
as a member. The above also shows this to be the case for Windows group membership.
The account is now added again, using the net rpc group utility:
root#net rpc group addmem "MIDEARTH\Engineers" ajt -Uroot%not24getroot#getent group Engineers Engineers:x:1000:jht,ajtroot#net rpc group members Engineers -Uroot%not24get MIDEARTH\jht MIDEARTH\ajt
In this example the members of the Windows Domain Users account are validated using
the net rpc group utility. Note the this contents of the UNIX/Linux group was shown
four paragraphs earlier. The Windows (domain) group membership is shown here:
root# net rpc group members "Domain Users" -Uroot%not24get
MIDEARTH\jht
MIDEARTH\lct
MIDEARTH\ajt
MIDEARTH\met
MIDEARTH\vlendecke
This express example shows that Windows group names are treated by Samba (as with MS Windows) in a case-insensitive manner:
root# net rpc group members "DomAiN USerS" -Uroot%not24get
MIDEARTH\jht
MIDEARTH\lct
MIDEARTH\ajt
MIDEARTH\met
MIDEARTH\vlendecke
An attempt to specify the group name as MIDEARTH\Domain Users in place of
just simply Domain Users will fail. The default behavior of the net rpc group
is to direct the command at the local machine. The Windows group is treated as being local to the machine.
If it is necessary to query another machine, its name can be specified using the -S
servername parameter to the net command.
It is possible in Windows (and now in Samba also) to create a local group that has members (contains),
domain users, and domain global groups. Creation of the local group demo is
achieved by executing:
root# net rpc group add demo -L -S MORDON -Uroot%not24get
The -L switch means create a local group. Use the -S argument to direct the operation to a particular server. The parameters to the -U argument should be for a user who has appropriate administrative right and privileges on the machine.
Addition and removal of group members can be achieved using the addmem and
delmem subcommands of net rpc group command. For example,
addition of “DOM\Domain Users” to the local group demo would be
done by executing:
root# net rpc group addmem demo "DOM\Domain Users" -Uroot%not24get
The members of a nested group can be listed by executing the following:
root# net rpc group members demo -Uroot%not24get
DOM\Domain Users
DOM\Engineers
DOM\jamesf
DOM\jht
Nested group members can be removed (deleted) as shown here:
root# net rpc group delmem demo "DOM\jht" -Uroot%not24get
Windows network administrators often ask on the Samba mailing list how it is possible to grant everyone administrative rights on their own workstation. This is of course a very bad practice, but commonly done to avoid user complaints. Here is how it can be done remotely from a Samba PDC or BDC:
root# net rpc group addmem "Administrators" "Domain Users" \
-S WINPC032 -Uadministrator%secret
This can be scripted, and can therefore be performed as a user logs onto the domain from a Windows workstation. Here is a simple example that shows how this can be done.
Procedure 13.1. Automating User Addition to the Workstation Power Users Group
Example 13.1. Script to Auto-add Domain Users to Workstation Power Users Group
#!/bin/bash
/usr/bin/net rpc group addmem "Power Users" "DOMAIN_NAME\$1" \
-UAdministrator%secret -S $2
exit 0
Create the script shown in ??? and locate it in
the directory /etc/samba/scripts, named as autopoweruser.sh.
Set the permissions on this script to permit it to be executed as part of the logon process:
root#chown root:root /etc/samba/autopoweruser.shroot#chmod 755 /etc/samba/autopoweruser.sh
Modify the smb.conf file so the NETLOGON stanza contains the parameters
shown in the Netlogon Example smb.conf file.
Ensure that every Windows workstation Administrator account has the same password that you have used in the script shown in the Netlogon Example smb.conf file
This script will be executed every time a user logs on to the network. Therefore every user will have local Windows workstation management rights. This could of course be assigned using a group, in which case there is little justification for the use of this procedure. The key justification for the use of this method is that it will guarantee that all users have appropriate rights on the workstation.
Every Windows network user account must be translated to a UNIX/Linux user account. In actual fact, the only account information the UNIX/Linux Samba server needs is a UID. The UID is available either from a system (POSIX) account or from a pool (range) of UID numbers that is set aside for the purpose of being allocated for use by Windows user accounts. In the case of the UID pool, the UID for a particular user will be allocated by winbindd.
Although this is not the appropriate place to discuss the username map facility,
this interface is an important method of mapping a Windows user account to a UNIX account that has a
different name. Refer to the man page for the smb.conf file for more information regarding this
facility. User name mappings cannot be managed using the net utility.
The syntax for adding a user account via the net (according to the man page) is shown here:
net [<method>] user ADD <name> [-c container] [-F user flags] \
[misc. options] [targets]
The user account password may be set using this syntax:
net rpc password <username> [<password>] -Uadmin_username%admin_pass
The following demonstrates the addition of an account to the server FRODO:
root# net rpc user add jacko -S FRODO -Uroot%not24get
Added user jacko
The account password can be set with the following methods (all show the same operation):
root#net rpc password jacko f4sth0rse -S FRODO -Uroot%not24getroot#net rpc user password jacko f4sth0rse \ -S FRODO -Uroot%not24get
Deletion of a user account can be done using the following syntax:
net [<method>] user DELETE <name> [misc. options] [targets]
The following command will delete the user account jacko:
root# net rpc user delete jacko -Uroot%not24get
Deleted user account
Two basic user account operations are routinely used: change of password and querying which groups a user is a member of. The change of password operation is shown in ???.
The ability to query Windows group membership can be essential. Here is how a remote server may be interrogated to find which groups a user is a member of:
root# net rpc user info jacko -S SAURON -Uroot%not24get
net rpc user info jacko -S SAURON -Uroot%not24get
Domain Users
Domain Admins
Engineers
TorridGroup
BOP Shop
Emergency Services
It is also possible to rename user accounts: oldusername newusername Note that this operation does not yet work against Samba Servers. It is, however, possible to rename useraccounts on Windows Servers.
In some situations it is unavoidable that a user's Windows logon name will differ from the login ID
that user has on the Samba server. It is possible to create a special file on the Samba server that
will permit the Windows user name to be mapped to a different UNIX/Linux user name. The smb.conf
file must also be amended so that the [global] stanza contains the parameter:
username map = /etc/samba/smbusers
The content of the /etc/samba/smbusers file is shown here:
parsonsw: "William Parsons" marygee: geeringm
In this example the Windows user account “William Parsons” will be mapped to the UNIX user
parsonsw, and the Windows user account “geeringm” will be mapped to the
UNIX user marygee.
With all versions of Samba earlier than 3.0.11 the only account on a Samba server that could
manage users, groups, shares, printers, and such was the root account. This caused
problems for some users and was a frequent source of scorn over the necessity to hand out the
credentials for the most security-sensitive account on a UNIX/Linux system.
New to Samba version 3.0.11 is the ability to delegate administrative privileges as necessary to either a normal user or to groups of users. The significance of the administrative privileges is documented in ???. Examples of use of the net for user rights and privilege management is appropriate to this chapter.
When user rights and privileges are correctly set, there is no longer a need for a Windows
network account for the root user (nor for any synonym of it) with a UNIX UID=0.
Initial user rights and privileges can be assigned by any account that is a member of the
Domain Admins group. Rights can be assigned to user as well as group accounts.
By default, no privileges and rights are assigned. This is demonstrated by executing the command shown here:
root# net rpc rights list accounts -U root%not24get
BUILTIN\Print Operators
No privileges assigned
BUILTIN\Account Operators
No privileges assigned
BUILTIN\Backup Operators
No privileges assigned
BUILTIN\Server Operators
No privileges assigned
BUILTIN\Administrators
No privileges assigned
Everyone
No privileges assigned
The net command can be used to obtain the currently supported capabilities for rights and privileges using this method:
root# net rpc rights list -U root%not24get
SeMachineAccountPrivilege Add machines to domain
SePrintOperatorPrivilege Manage printers
SeAddUsersPrivilege Add users and groups to the domain
SeRemoteShutdownPrivilege Force shutdown from a remote system
SeDiskOperatorPrivilege Manage disk shares
SeBackupPrivilege Back up files and directories
SeRestorePrivilege Restore files and directories
SeTakeOwnershipPrivilege Take ownership of files or other objects
Machine account privilege is necessary to permit a Windows NT4 or later network client to be added to the domain. The disk operator privilege is necessary to permit the user to manage share ACLs and file and directory ACLs for objects not owned by the user.
In this example, all rights are assigned to the Domain Admins group. This is a good
idea since members of this group are generally expected to be all-powerful. This assignment makes that
the reality:
root# net rpc rights grant "MIDEARTH\Domain Admins" \
SeMachineAccountPrivilege SePrintOperatorPrivilege \
SeAddUsersPrivilege SeRemoteShutdownPrivilege \
SeDiskOperatorPrivilege -U root%not24get
Successfully granted rights.
Next, the domain user jht is given the privileges needed for day-to-day
administration:
root# net rpc rights grant "MIDEARTH\jht" \
SeMachineAccountPrivilege SePrintOperatorPrivilege \
SeAddUsersPrivilege SeDiskOperatorPrivilege \
-U root%not24get
Successfully granted rights.
The following step permits validation of the changes just made:
root# net rpc rights list accounts -U root%not24get
MIDEARTH\jht
SeMachineAccountPrivilege
SePrintOperatorPrivilege
SeAddUsersPrivilege
SeDiskOperatorPrivilege
BUILTIN\Print Operators
No privileges assigned
BUILTIN\Account Operators
No privileges assigned
BUILTIN\Backup Operators
No privileges assigned
BUILTIN\Server Operators
No privileges assigned
BUILTIN\Administrators
No privileges assigned
Everyone
No privileges assigned
MIDEARTH\Domain Admins
SeMachineAccountPrivilege
SePrintOperatorPrivilege
SeAddUsersPrivilege
SeRemoteShutdownPrivilege
SeDiskOperatorPrivilege
There are essentially two types of trust relationships: the first is between domain controllers and domain member machines (network clients), the second is between domains (called interdomain trusts). All Samba servers that participate in domain security require a domain membership trust account, as do like Windows NT/200x/XP workstations.
The net command looks in the smb.conf file to obtain its own configuration settings. Thus, the following
command 'knows' which domain to join from the smb.conf file.
A Samba server domain trust account can be validated as shown in this example:
root# net rpc testjoin
Join to 'MIDEARTH' is OK
Where there is no domain membership account, or when the account credentials are not valid, the following results will be observed:
net rpc testjoin -S DOLPHIN Join to domain 'WORLDOCEAN' is not valid
The equivalent command for joining a Samba server to a Windows ADS domain is shown here:
root# net ads testjoin
Using short domain name -- TAKEAWAY
Joined 'LEMONADE' to realm 'TAKEAWAY.BIZ'
In the event that the ADS trust was not established, or is broken for one reason or another, the following error message may be obtained:
root# net ads testjoin -UAdministrator%secret
Join to domain is not valid
The following demonstrates the process of creating a machine trust account in the target domain for the Samba server from which the command is executed:
root# net rpc join -S FRODO -Uroot%not24get
Joined domain MIDEARTH.
The joining of a Samba server to a Samba domain results in the creation of a machine account. An example of this is shown here:
root# pdbedit -Lw merlin\$
merlin$:1009:9B4489D6B90461FD6A3EC3AB96147E16:\
176D8C554E99914BDF3407DEA2231D80:[S ]:LCT-42891919:
The S in the square brackets means this is a server (PDC/BDC) account. The domain join can be cast to join purely as a workstation, in which case the S is replaced with a W (indicating a workstation account). The following command can be used to affect this:
root# net rpc join member -S FRODO -Uroot%not24get
Joined domain MIDEARTH.
Note that the command-line parameter member makes this join specific. By default
the type is deduced from the smb.conf file configuration. To specifically join as a PDC or BDC, the
command-line parameter will be [PDC | BDC]. For example:
root# net rpc join bdc -S FRODO -Uroot%not24get
Joined domain MIDEARTH.
It is best to let Samba figure out the domain join type from the settings in the smb.conf file.
The command to join a Samba server to a Windows ADS domain is shown here:
root# net ads join -UAdministrator%not24get
Using short domain name -- GDANSK
Joined 'FRANDIMITZ' to realm 'GDANSK.ABMAS.BIZ'
There is no specific option to remove a machine account from an NT4 domain. When a domain member that is a Windows machine is withdrawn from the domain, the domain membership account is not automatically removed either. Inactive domain member accounts can be removed using any convenient tool. If necessary, the machine account can be removed using the following net command:
root# net rpc user delete HERRING\$ -Uroot%not24get
Deleted user account.
The removal is made possible because machine accounts are just like user accounts with a trailing $ character. The account management operations treat user and machine accounts in like manner.
A Samba-3 server that is a Windows ADS domain member can execute the following command to detach from the domain:
root# net ads leave
Detailed information regarding an ADS domain can be obtained by a Samba DMS machine by executing the following:
root# net ads status
The volume of information is extensive. Please refer to the book “Samba-3 by Example”, Chapter 7 for more information regarding its use. This book may be obtained either in print or online from the Samba-3 by Example.
Interdomain trust relationships form the primary mechanism by which users from one domain can be granted access rights and privileges in another domain.
To discover what trust relationships are in effect, execute this command:
root# net rpc trustdom list -Uroot%not24get
Trusted domains list:
none
Trusting domains list:
none
There are no interdomain trusts at this time; the following steps will create them.
It is necessary to create a trust account in the local domain. A domain controller in a second domain can create a trusted connection with this account. That means that the foreign domain is being trusted to access resources in the local domain. This command creates the local trust account:
root# net rpc trustdom add DAMNATION f00db4r -Uroot%not24get
The account can be revealed by using the pdbedit as shown here:
root# pdbedit -Lw DAMNATION\$
DAMNATION$:1016:9AC1F121DF897688AAD3B435B51404EE: \
7F845808B91BB9F7FEF44B247D9DC9A6:[I ]:LCT-428934B1:
A trust account will always have an I in the field within the square brackets.
If the trusting domain is not capable of being reached, the following command will fail:
root# net rpc trustdom list -Uroot%not24get
Trusted domains list:
none
Trusting domains list:
DAMNATION S-1-5-21-1385457007-882775198-1210191635
The above command executed successfully; a failure is indicated when the following response is obtained:
net rpc trustdom list -Uroot%not24get Trusted domains list: DAMNATION S-1-5-21-1385457007-882775198-1210191635 Trusting domains list: DAMNATION domain controller is not responding
Where a trust account has been created on a foreign domain, Samba is able to establish the trust (connect with) the foreign account. In the process it creates a one-way trust to the resources on the remote domain. This command achieves the objective of joining the trust relationship:
root# net rpc trustdom establish DAMNATION
Password: xxxxxxx == f00db4r
Could not connect to server TRANSGRESSION
Trust to domain DAMNATION established
Validation of the two-way trust now established is possible as shown here:
root# net rpc trustdom list -Uroot%not24get
Trusted domains list:
DAMNATION S-1-5-21-1385457007-882775198-1210191635
Trusting domains list:
DAMNATION S-1-5-21-1385457007-882775198-1210191635
Sometimes it is necessary to remove the ability for local users to access a foreign domain. The trusting connection can be revoked as shown here:
root# net rpc trustdom revoke DAMNATION -Uroot%not24get
At other times it becomes necessary to remove the ability for users from a foreign domain to be able to access resources in the local domain. The command shown here will do that:
root# net rpc trustdom del DAMNATION -Uroot%not24get
The basic security identifier that is used by all Windows networking operations is the Windows security identifier (SID). All Windows network machines (servers and workstations), users, and groups are identified by their respective SID. All desktop profiles are also encoded with user and group SIDs that are specific to the SID of the domain to which the user belongs.
It is truly prudent to store the machine and/or domain SID in a file for safekeeping. Why? Because a change in hostname or in the domain (workgroup) name may result in a change in the SID. When you have the SID on hand, it is a simple matter to restore it. The alternative is to suffer the pain of having to recover user desktop profiles and perhaps rejoin all member machines to the domain.
First, do not forget to store the local SID in a file. It is a good idea to put this in the directory
in which the smb.conf file is also stored. Here is a simple action to achieve this:
root# net getlocalsid > /etc/samba/my-sid
Good, there is now a safe copy of the local machine SID. On a PDC/BDC this is the domain SID also.
The following command reveals what the former one should have placed into the file called
my-sid:
root# net getlocalsid
SID for domain MERLIN is: S-1-5-21-726309263-4128913605-1168186429
If ever it becomes necessary to restore the SID that has been stored in the my-sid
file, simply copy the SID (the string of characters that begins with S-1-5-21) to
the command line shown here:
root# net setlocalsid S-1-5-21-1385457007-882775198-1210191635
Restoration of a machine SID is a simple operation, but the absence of a backup copy can be very problematic.
The following operation is useful only for machines that are being configured as a PDC or a BDC. DMS and workstation clients should have their own machine SID to avoid any potential namespace collision. Here is the way that the BDC SID can be synchronized to that of the PDC (this is the default NT4 domain practice also):
root# net rpc getsid -S FRODO -Uroot%not24get
Storing SID S-1-5-21-726309263-4128913605-1168186429 \
for Domain MIDEARTH in secrets.tdb
Usually it is not necessary to specify the target server (-S FRODO) or the administrator account credentials (-Uroot%not24get).
Share management is central to all file serving operations. Typical share operations include:
Creation/change/deletion of shares
Setting/changing ACLs on shares
Moving shares from one server to another
Change of permissions of share contents
Each of these are dealt with here insofar as they involve the use of the net command. Operations outside of this command are covered elsewhere in this document.
A share can be added using the net rpc share command capabilities.
The target machine may be local or remote and is specified by the -S option. It must be noted
that the addition and deletion of shares using this tool depends on the availability of a suitable
interface script. The interface scripts Sambas smbd uses are called
add share command, delete share command and
change share command A set of example scripts are provided in the Samba source
code tarball in the directory ~samba/examples/scripts.
The following steps demonstrate the use of the share management capabilities of the net
utility. In the first step a share called Bulge is added. The sharepoint within the
file system is the directory /data. The command that can be executed to perform the
addition of this share is shown here:
root# net rpc share add Bulge=/data -S MERLIN -Uroot%not24get
Validation is an important process, and by executing the command net rpc share with no other operators it is possible to obtain a listing of available shares, as shown here:
root# net rpc share -S MERLIN -Uroot%not24get
profdata
archive
Bulge <--- This one was added
print$
netlogon
profiles
IPC$
kyocera
ADMIN$
Often it is desirable also to permit a share to be removed using a command-line tool. The following step permits the share that was previously added to be removed:
root# net rpc share delete Bulge -S MERLIN -Uroot%not24get
A simple validation shown here demonstrates that the share has been removed:
root# net rpc share -S MERLIN -Uroot%not24get
profdata
archive
print$
netlogon
profiles
IPC$
ADMIN$
kyocera
At this time the net tool cannot be used to manage ACLs on Samba shares. In MS Windows language this is called Share Permissions.
It is possible to set ACLs on Samba shares using either the SRVTOOLS NT4 Domain Server Manager or using the Computer Management MMC snap-in. Neither is covered here, but see ???.
Shares and files can be migrated in the same manner as user, machine, and group accounts. It is possible to preserve access control settings (ACLs) as well as security settings throughout the migration process. The net rpc vampire facility is used to migrate accounts from a Windows NT4 (or later) domain to a Samba server. This process preserves passwords and account security settings and is a precursor to the migration of shares and files.
The net rpc share command may be used to migrate shares, directories, files, and all relevant data from a Windows server to a Samba server.
A set of command-line switches permit the creation of almost direct clones of Windows file servers. For example, when migrating a fileserver, file ACLs and DOS file attributes from the Windows server can be included in the migration process and will reappear, almost identically, on the Samba server when the migration has been completed.
The migration process can be completed only with the Samba server already being fully operational. The user and group accounts must be migrated before attempting to migrate data share, files, and printers. The migration of files and printer configurations involves the use of both SMB and MS DCE RPC services. The benefit of the manner in which the migration process has been implemented is that the possibility now exists to use a Samba server as a man-in-middle migration service that affects a transfer of data from one server to another. For example, if the Samba server is called MESSER, the source Windows NT4 server is called PEPPY, and the target Samba server is called GONZALES, the machine MESSER can be used to effect the migration of all data (files and shares) from PEPPY to GONZALES. If the target machine is not specified, the local server is assumed by default - as net's general rule of thumb .
The success of server migration requires a firm understanding of the structure of the source server (or domain) as well as the processes on which the migration is critically dependant.
There are two known limitations to the migration process:
The net command requires that the user credentials provided exist on both the migration source and the migration target.
Printer settings may not be fully or may be incorrectly migrated. This might in particular happen when migrating a Windows 2003 print server to Samba.
The net rpc share migrate command operation permits the migration of plain share stanzas. A stanza contains the parameters within which a file or print share are defined. The use of this migration method will create share stanzas that have as parameters the file system directory path, an optional description, and simple security settings that permit write access to files. One of the first steps necessary following migration is to review the share stanzas to ensure that the settings are suitable for use.
The shares are created on the fly as part of the migration process. The smbd
application does this by calling on the operating system to execute the script specified by the
smb.conf parameter add share command.
There is a suitable example script for the add share command in the
$SAMBA_SOURCES/examples/scripts directory. It should be noted that
the account that is used to drive the migration must, of necessity, have appropriate file system
access privileges and have the right to create shares and to set ACLs on them. Such rights are
conferred by these rights: SeAddUsersPrivilege and SeDiskOperatorPrivilege.
For more information regarding rights and privileges please refer to ???.
The syntax of the share migration command is shown here:
net rpc share MIGRATE SHARES <share-name> -S <source>
[--destination=localhost] [--exclude=share1,share2] [-v]
When the parameter <share-name> is omitted, all shares will be migrated. The potentially
large list of available shares on the system that is being migrated can be limited using the
--exclude switch. For example:
root# net rpc share migrate shares myshare\
-S win2k -U administrator%secret"
This will migrate the share myshare from the server win2k
to the Samba Server using the permissions that are tied to the account administrator
with the password secret. The account that is used must be the same on both the
migration source server and the target Samba server. The use of the net rpc
vampire, prior to attempting the migration of shares, will ensure that accounts will be
identical on both systems. One precaution worth taking before commencement of migration of shares is
to validate that the migrated accounts (on the Samba server) have the needed rights and privileges.
This can be done as shown here:
root# net rpc right list accounts -Uroot%not24get
The steps taken so far perform only the migration of shares. Directories and directory contents are not migrated by the steps covered up to this point.
Everything covered to this point has been done in preparation for the migration of file and directory data. For many people preparation is potentially boring and the real excitement only begins when file data can be used. The next steps demonstrate the techniques that can be used to transfer (migrate) data files using the net command.
Transfer of files from one server to another has always been a challenge for MS Windows administrators because Windows NT and 200X servers do not always include the tools needed. The xcopy from Windows NT is not capable of preserving file and directory ACLs, it does so only with Windows 200x. Microsoft does provide a utility that can copy ACLs (security settings) called scopy, but it is provided only as part of the Windows NT or 200X Server Resource Kit.
There are several tools, both commercial and freeware, that can be used from a Windows server to copy files and directories with full preservation of security settings. One of the best known of the free tools is called robocopy.
The net utility can be used to copy files and directories with full preservation of ACLs as well as DOS file attributes. Note that including ACLs makes sense only where the destination system will operate within the same security context as the source system. This applies both to a DMS and to domain controllers that result from a vampired domain. Before file and directory migration, all shares must already exist.
The syntax for the migration commands is shown here:
net rpc share MIGRATE FILES <share-name> -S <source>
[--destination=localhost] [--exclude=share1,share2]
[--acls] [--attrs] [--timestamps] [-v]
If the <share-name> parameter is omitted, all shares will be migrated. The potentially large
list of shares on the source system can be restricted using the --exclude command
switch.
Where it is necessary to preserve all file ACLs, the --acls switch should be added
to the above command line. Original file timestamps can be preserved by specifying the
--timestamps switch, and the DOS file attributes (i.e., hidden, archive, etc.) can
be preserved by specifying the --attrs switch.
The ability to preserve ACLs depends on appropriate support for ACLs as well as the general file system semantics of the host operating system on the target server. A migration from one Windows file server to another will perfectly preserve all file attributes. Because of the difficulty of mapping Windows ACLs onto a POSIX ACLs-supporting system, there can be no perfect migration of Windows ACLs to a Samba server.
The ACLs that result on a Samba server will most probably not match the originating ACLs. Windows supports
the possibility of files that are owned only by a group. Group-alone file ownership is not possible under
UNIX/Linux. Errors in migrating group-owned files can be avoided by using the smb.conf file
force unknown acl user = yes parameter. This facility will
automatically convert group-owned files into correctly user-owned files on the Samba server.
An example for migration of files from a machine called nt4box to the Samba server
from which the process will be handled is shown here:
root# net rpc share migrate files -S nt4box --acls \
--attrs -U administrator%secret
This command will migrate all files and directories from all file shares on the Windows server called
nt4box to the Samba server from which migration is initiated. Files that are group-owned
will be owned by the user account administrator.
It is possible to have share-ACLs (security descriptors) that won't allow you, even as Administrator, to copy any files or directories into it. Therefor the migration of the share-ACLs has been put into a separate function:
root# net rpc share migrate security -S nt4box -U administrator%secret
This command will only copy the share-ACL of each share on nt4box to your local samba-system.
The operating mode shown here is just a combination of the previous three. It first migrates share definitions and then all shared files and directories and finally migrates the share-ACLs:
net rpc share MIGRATE ALL <share-name> -S <source>
[--exclude=share1, share2] [--acls] [--attrs] [--timestamps] [-v]
An example of simultaneous migration is shown here:
root# net rpc share migrate all -S w2k3server -U administrator%secret
This will generate a complete server clone of the w2k3server server.
The installation of a new server, as with the migration to a new network environment, often is similar to building a house; progress is very rapid from the laying of foundations up to the stage at which the house can be locked up, but the finishing off appears to take longer and longer as building approaches completion.
Printing needs vary greatly depending on the network environment and may be very simple or complex. If the need is very simple, the best solution to the implementation of printing support may well be to re-install everything from a clean slate instead of migrating older configurations. On the other hand, a complex network that is integrated with many international offices and a multiplexity of local branch offices, each of which form an inter-twined maze of printing possibilities, the ability to migrate all printer configurations is decidedly beneficial. To manually re-establish a complex printing network will take much time and frustration. Often it will not be possible to find driver files that are currently in use, necessitating the installation of newer drivers. Newer drivers often implement printing features that will necessitate a change in the printer usage. Additionally, with very complex printer configurations it becomes almost impossible to re-create the same environment no matter how extensively it has been documented.
The migration of an existing printing architecture involves the following:
Establishment of print queues.
Installation of printer drivers (both for the print server and for Windows clients.
Configuration of printing forms.
Implementation of security settings.
Configuration of printer settings.
The Samba net utility permits printer migration from one Windows print server
to another. When this tool is used to migrate printers to a Samba server smbd,
the application that receives the network requests to create the necessary services must call out
to the operating system in order to create the underlying printers. The call-out is implemented
by way of an interface script that can be specified by the smb.conf file parameter
. This script is essential to the migration process.
A suitable example script may be obtained from the $SAMBA_SOURCES/examples/scripts
directory. Take note that this script must be customized to suit the operating system environment
and may use its tools to create a print queue.
Each of the components listed above can be completed separately, or they can be completed as part of an automated operation. Many network administrators prefer to deal with migration issues in a manner that gives them the most control, particularly when things go wrong. The syntax for each operation is now briefly described.
Printer migration from a Windows print server (NT4 or 200x) is shown. This instruction causes the printer share to be created together with the underlying print queue:
net rpc printer MIGRATE PRINTERS [printer] [misc. options] [targets]
Printer drivers can be migrated from the Windows print server to the Samba server using this command-line instruction:
net rpc printer MIGRATE DRIVERS [printer] [misc. options] [targets]
Printer forms can be migrated with the following operation:
net rpc printer MIGRATE FORMS [printer] [misc. options] [targets]
Printer security settings (ACLs) can be migrated from the Windows server to the Samba server using this command:
net rpc printer MIGRATE SECURITY [printer] [misc. options] [targets]
Printer configuration settings include factors such as paper size and default paper orientation. These can be migrated from the Windows print server to the Samba server with this command:
net rpc printer MIGRATE SETTINGS [printer] [misc. options] [targets]
Migration of printers including the above-mentioned sets of information may be completed with a single command using this syntax:
net rpc printer MIGRATE ALL [printer] [misc. options] [targets]
The man page documents the net file function suite, which provides the tools to close open files using either RAP or RPC function calls. Please refer to the man page for specific usage information.
The session management interface of the net session command uses the old RAP method to obtain the list of connections to the Samba server, as shown here:
root# net rap session -S MERLIN -Uroot%not24get
Computer User name Client Type Opens Idle time
------------------------------------------------------------------------------
\\merlin root Unknown Client 0 00:00:00
\\marvel jht Unknown Client 0 00:00:00
\\maggot jht Unknown Client 0 00:00:00
\\marvel jht Unknown Client 0 00:00:00
A session can be closed by executing a command as shown here:
root# net rap session close marvel -Uroot%not24get
When Samba-3 is used within an MS Windows ADS environment, printers shared via Samba will not be browseable until they have been published to the ADS domain. Information regarding published printers may be obtained from the ADS server by executing the net ads print info command following this syntax:
net ads printer info <printer_name> <server_name> -Uadministrator%secret
If the asterisk (*) is used in place of the printer_name argument, a list of all printers will be returned.
To publish (make available) a printer to ADS, execute the following command:
net ads printer publish <printer_name> -Uadministrator%secret
This publishes a printer from the local Samba server to ADS.
Removal of a Samba printer from ADS is achieved by executing this command:
net ads printer remove <printer_name> -Uadministrator%secret
A generic search (query) can also be made to locate a printer across the entire ADS domain by executing:
net ads printer search <printer_name> -Uadministrator%secret
Please refer to the net command man page for information regarding cache management.
The IDMAP UID to SID, and SID to UID, mappings that are created by winbindd can be backed up to a text file. The text file can be manually edited, although it is highly recommended that you attempt this only if you know precisely what you are doing.
An IDMAP text dump file can be restored (or reloaded). There are two situations that may necessitate this action: a) The existing IDMAP file is corrupt, b) It is necessary to install an editted version of the mapping information.
Winbind must be shut down to dump the IDMAP file. Before restoring a dump file, shut down
winbindd and delete the old winbindd_idmap.tdb file.
The IDMAP database can be dumped to a text file as shown here:
net idmap dump <full_path_and_tdb_filename> > dumpfile.txt
Where a particular build of Samba the run-time tdb files are stored in the
/var/lib/samba directory the following commands to create the dump file will suffice:
net idmap dump /var/lib/samba/winbindd_idmap.tdb > idmap_dump.txt
The IDMAP dump file can be restored using the following command:
net idmap restore <full_path_and_tdb_filename> < dumpfile.txt
Where the Samba run-time tdb files are stored in the /var/lib/samba directory
the following command can be used to restore the data to the tdb file:
net idmap restore /var/lib/samba/winbindd_idmap.tdb < idmap_dump.txt
The following command is useful for obtaining basic statistics regarding a Samba domain. This command does not work with current Windows XP Professional clients.
root# net rpc info
Domain Name: RAPIDFLY
Domain SID: S-1-5-21-399034208-633907489-3292421255
Sequence number: 1116312355
Num users: 720
Num domain groups: 27
Num local groups: 6
Another useful tool is the net time tool set. This tool may be used to query the current time on the target server as shown here:
root# net time -S SAURON
Tue May 17 00:50:43 2005
In the event that it is the intent to pass the time information obtained to the UNIX /bin/time, it is a good idea to obtain the time from the target server in a format that is ready to be passed through. This may be done by executing:
root# net time system -S FRODO
051700532005.16
The time can be set on a target server by executing:
root# net time set -S MAGGOT -U Administrator%not24get
Tue May 17 00:55:30 MDT 2005
It is possible to obtain the time zone of a server by executing the following command against it:
root# net time zone -S SAURON
-0600