How to Configure Samba 2.2 as a Primary Domain Controller

Prerequisite Reading

Before you continue reading in this chapter, please make sure that you are comfortable with configuring basic files services in smb.conf and how to enable and administer password encryption in Samba. Theses two topics are covered in the smb.conf(5) manpage and the Encryption chapter of this HOWTO Collection.

Background

Note: Author's Note : This document is a combination of David Bannon's Samba 2.2 PDC HOWTO and the Samba NT Domain FAQ. Both documents are superseded by this one.

Version of Samba prior to release 2.2 had marginal capabilities to act as a Windows NT 4.0 Primary DOmain Controller (PDC). Beginning with Samba 2.2.0, we are proud to announce official support for Windows NT 4.0 style domain logons from Windows NT 4.0 (through SP6) and Windows 2000 (through SP1) clients. This article outlines the steps necessary for configuring Samba as a PDC. It is necessary to have a working Samba server prior to implementing the PDC functionality. If you have not followed the steps outlined in UNIX_INSTALL.html, please make sure that your server is configured correctly before proceeding. Another good resource in the smb.conf(5) man page. The following functionality should work in 2.2:

Windows 2000 Service Pack 2 Clients

Samba 2.2.1 is required for PDC functionality when using Windows 2000 SP2 clients.

The following pieces of functionality are not included in the 2.2 release:

Please note that Windows 9x clients are not true members of a domain for reasons outlined in this article. Therefore the protocol for support Windows 9x style domain logons is completely different from NT4 domain logons and has been officially supported for some time.

Implementing a Samba PDC can basically be divided into 2 broad steps.

  1. Configuring the Samba PDC

  2. Creating machine trust accounts and joining clients to the domain

There are other minor details such as user profiles, system policies, etc... However, these are not necessarily specific to a Samba PDC as much as they are related to Windows NT networking concepts. They will be mentioned only briefly here.

Configuring the Samba Domain Controller

The first step in creating a working Samba PDC is to understand the parameters necessary in smb.conf. I will not attempt to re-explain the parameters here as they are more that adequately covered in the smb.conf man page. For convenience, the parameters have been linked with the actual smb.conf description.

Here is an example smb.conf for acting as a PDC:

[global]
    ; Basic server settings
    netbios name = POGO
    workgroup = NARNIA

    ; we should act as the domain and local master browser
    os level = 64
    preferred master = yes
    domain master = yes
    local master = yes
    
    ; security settings (must user security = user)
    security = user
    
    ; encrypted passwords are a requirement for a PDC
    encrypt passwords = yes
    
    ; support domain logons
    domain logons = yes
    
    ; where to store user profiles?
    logon path = \\%N\profiles\%u
    
    ; where is a user's home directory and where should it
    ; be mounted at?
    logon drive = H:
    logon home = \\homeserver\%u
    
    ; specify a generic logon script for all users
    ; this is a relative **DOS** path to the [netlogon] share
    logon script = logon.cmd

; necessary share for domain controller
[netlogon]
    path = /usr/local/samba/lib/netlogon
    writeable = no
    write list = ntadmin
    
; share for storing user profiles
[profiles]
    path = /export/smb/ntprofile
    writeable = yes
    create mask = 0600
    directory mask = 0700

There are a couple of points to emphasize in the above configuration.

As Samba 2.2 does not offer a complete implementation of group mapping between Windows NT groups and UNIX groups (this is really quite complicated to explain in a short space), you should refer to the domain admin group smb.conf parameter for information of creating "Domain Admins" style accounts.

Creating Machine Trust Accounts and Joining Clients to the Domain

A machine trust account is a samba user account owned by a computer. The account password acts as the shared secret for secure communication with the Domain Controller. This is a security feature to prevent an unauthorized machine with the same NetBIOS name from joining the domain and gaining access to domain user/group accounts. Hence a Windows 9x host is never a true member of a domain because it does not posses a machine trust account, and thus has no shared secret with the DC.

On a Windows NT PDC, these machine trust account passwords are stored in the registry. A Samba PDC stores these accounts in the same location as user LanMan and NT password hashes (currently smbpasswd). However, machine trust accounts only possess and use the NT password hash.

Because Samba requires machine accounts to possess a UNIX uid from which an Windows NT SID can be generated, all of these accounts must have an entry in /etc/passwd and smbpasswd. Future releases will alleviate the need to create /etc/passwd entries.

There are two means of creating machine trust accounts.

Manually creating machine trust accounts

The first step in creating a machine trust account by hand is to create an entry for the machine in /etc/passwd. This can be done using vipw or any 'add userr' command which is normally used to create new UNIX accounts. The following is an example for a Linux based Samba server:

root# /usr/sbin/useradd -g 100 -d /dev/null -c "machine nickname" -s /bin/false machine_name$

root# passwd -l machine_name$

The /etc/passwd entry will list the machine name with a $ appended, won't have a passwd, will have a null shell and no home directory. For example a machine called 'doppy' would have an /etc/passwd entry like this :

doppy$:x:505:501:machine_nickname:/dev/null:/bin/false

Above, machine_nickname can be any descriptive name for the pc i.e. BasementComputer. The machine_name absolutely must be the NetBIOS name of the pc to be added to the domain. The "$" must append the NetBIOS name of the pc or samba will not recognize this as a machine account

Now that the UNIX account has been created, the next step is to create the smbpasswd entry for the machine containing the well known initial trust account password. This can be done using the smbpasswd(8) command as shown here:

root# smbpasswd -a -m machine_name

where machine_name is the machine's NetBIOS name.

Join the client to the domain immediately

Manually creating a machine trust account using this method is the equivalent of creating a machine account on a Windows NT PDC using the "Server Manager". From the time at which the account is created to the time which th client joins the domain and changes the password, your domain is vulnerable to an intruder joining your domain using a a machine with the same NetBIOS name. A PDC inherently trusts members of the domain and will serve out a large degree of user information to such clients. You have been warned!

Creating machine trust accounts "on the fly"

The second, and most recommended way of creating machine trust accounts is to create them as needed at the time the client is joined to the domain. You will need to include a value for the add user script parameter. Below is an example from a RedHat 6.2 Linux system.

add user script = /usr/sbin/useradd -d /dev/null -g 100 -s /bin/false -M %u

In Samba 2.2.1, only the root account can be used to create machine accounts like this. Therefore, it is required to create an entry in smbpasswd for root. The password SHOULD be set to a different password that the associated /etc/passwd entry for security reasons.

Common Problems and Errors

System Policies and Profiles

Much of the information necessary to implement System Policies and Roving User Profiles in a Samba domain is the same as that for implementing these same items in a Windows NT 4.0 domain. You should read the white paper Implementing Profiles and Policies in Windows NT 4.0 available from Microsoft.

Here are some additional details:

What other help can I get ?

There are many sources of information available in the form of mailing lists, RFC's and documentation. The docs that come with the samba distribution contain very good explanations of general SMB topics such as browsing.

Domain Control for Windows 9x/ME

Note: The following section contains much of the original DOMAIN.txt file previously included with Samba. Much of the material is based on what went into the book Special Edition, Using Samba. (Richard Sharpe)

A domain and a workgroup are exactly the same thing in terms of network browsing. The difference is that a distributable authentication database is associated with a domain, for secure login access to a network. Also, different access rights can be granted to users if they successfully authenticate against a domain logon server (NT server and other systems based on NT server support this, as does at least Samba TNG now).

The SMB client logging on to a domain has an expectation that every other server in the domain should accept the same authentication information. Network browsing functionality of domains and workgroups is identical and is explained in BROWSING.txt. It should be noted, that browsing is total orthogonal to logon support.

Issues related to the single-logon network model are discussed in this document. Samba supports domain logons, network logon scripts, and user profiles for MS Windows for workgroups and MS Windows 9X clients.

When an SMB client in a domain wishes to logon it broadcast requests for a logon server. The first one to reply gets the job, and validates its password using whatever mechanism the Samba administrator has installed. It is possible (but very stupid) to create a domain where the user database is not shared between servers, i.e. they are effectively workgroup servers advertising themselves as participating in a domain. This demonstrates how authentication is quite different from but closely involved with domains.

Another thing commonly associated with single-logon domains is remote administration over the SMB protocol. Again, there is no reason why this cannot be implemented with an underlying username database which is different from the Windows NT SAM. Support for the Remote Administration Protocol is planned for a future release of Samba.

Network logon support as discussed in this section is aimed at Window for Workgroups, and Windows 9X clients.

Support for profiles is confirmed as working for Win95, NT 4.0 and NT 3.51. It is possible to specify: the profile location; script file to be loaded on login; the user's home directory; and for NT a kick-off time could also now easily be supported. However, there are some differences between Win9X profile support and WinNT profile support. These are discussed below.

With NT Workstations, all this does not require the use or intervention of an NT 4.0 or NT 3.51 server: Samba can now replace the logon services provided by an NT server, to a limited and experimental degree (for example, running "User Manager for Domains" will not provide you with access to a domain created by a Samba Server).

With Win95, the help of an NT server can be enlisted, both for profile storage and for user authentication. For details on user authentication, see security_level.txt. For details on profile storage, see below.

Using these features you can make your clients verify their logon via the Samba server; make clients run a batch file when they logon to the network and download their preferences, desktop and start menu.

Before launching into the configuration instructions, it is worthwhile looking at how a Win9X client performs a logon:

  1. The client broadcasts (to the IP broadcast address of the subnet it is in) a NetLogon request. This is sent to the NetBIOS address DOMAIN<00> at the NetBIOS layer. The client chooses the first response it receives, which contains the NetBIOS name of the logon server to use in the format of \\SERVER.

  2. The client then connects to that server, logs on (does an SMBsessetupX) and then connects to the IPC$ share (using an SMBtconX).

  3. The client then does a NetWkstaUserLogon request, which retrieves the name of the user's logon script.

  4. The client then connects to the NetLogon share and searches for this and if it is found and can be read, is retrieved and executed by the client. After this, the client disconnects from the NetLogon share.

  5. The client then sends a NetUserGetInfo request to the server, to retrieve the user's home share, which is used to search for profiles. Since the response to the NetUserGetInfo request does not contain much more the user's home share, profiles for Win9X clients MUST reside in the user home directory.

  6. The client then connects to the user's home share and searches for the user's profile. As it turns out, you can specify the user's home share as a sharename and path. For example, \\server\fred\.profile. If the profiles are found, they are implemented.

  7. The client then disconnects from the user's home share, and reconnects to the NetLogon share and looks for CONFIG.POL, the policies file. If this is found, it is read and implemented.

Configuration Instructions: Network Logons

To use domain logons and profiles you need to do the following:

  1. Create a share called [netlogon] in your smb.conf. This share should be readable by all users, and probably should not be writeable. This share will hold your network logon scripts, and the CONFIG.POL file (Note: for details on the CONFIG.POL file, how to use it, what it is, refer to the Microsoft Windows NT Administration documentation. The format of these files is not known, so you will need to use Microsoft tools).

    For example I have used: 

    [netlogon]
     path = /data/dos/netlogon
     writeable = no
     guest ok = no

    Note that it is important that this share is not writeable by ordinary users, in a secure environment: ordinary users should not be allowed to modify or add files that another user's computer would then download when they log in.

  2. in the [global] section of smb.conf set the following: 

    domain logons = yes
logon script = %U.bat

    The choice of batch file is, of course, up to you. The above would give each user a separate batch file as the %U will be changed to their username automatically. The other standard % macros may also be used. You can make the batch files come from a subdirectory by using something like: 

    logon script = scripts\%U.bat

  3. create the batch files to be run when the user logs in. If the batch file doesn't exist then no batch file will be run.

    In the batch files you need to be careful to use DOS style cr/lf line endings. If you don't then DOS may get confused. I suggest you use a DOS editor to remotely edit the files if you don't know how to produce DOS style files under unix.

  4. Use smbclient with the -U option for some users to make sure that the \\server\NETLOGON share is available, the batch files are visible and they are readable by the users.

  5. you will probably find that your clients automatically mount the \\SERVER\NETLOGON share as drive z: while logging in. You can put some useful programs there to execute from the batch files.

security mode and master browsers

There are a few comments to make in order to tie up some loose ends. There has been much debate over the issue of whether or not it is ok to configure Samba as a Domain Controller in security modes other than USER. The only security mode which will not work due to technical reasons is SHARE mode security. DOMAIN and SERVER mode security is really just a variation on SMB user level security.

Actually, this issue is also closer tied to the debate on whether or not Samba must be the domain master browser for its workgroup when operating as a DC. While it may technically be possible to configure a server as such (after all, browsing and domain logons are two distinctly different functions), it is not a good idea to so. You should remember that the DC must register the DOMAIN#1b NetBIOS name. This is the name used by Windows clients to locate the DC. Windows clients do not distinguish between the DC and the DMB. For this reason, it is very wise to configure the Samba DC as the DMB.

Now back to the issue of configuring a Samba DC to use a mode other than "security = user". If a Samba host is configured to use another SMB server or DC in order to validate user connection requests, then it is a fact that some other machine on the network (the "password server") knows more about user than the Samba host. 99% of the time, this other host is a domain controller. Now in order to operate in domain mode security, the "workgroup" parameter must be set to the name of the Windows NT domain (which already has a domain controller, right?)

Therefore configuring a Samba box as a DC for a domain that already by definition has a PDC is asking for trouble. Therefore, you should always configure the Samba DC to be the DMB for its domain.

Configuration Instructions: Setting up Roaming User Profiles

Warning

NOTE! Roaming profiles support is different for Win9X and WinNT.

Before discussing how to configure roaming profiles, it is useful to see how Win9X and WinNT clients implement these features.

Win9X clients send a NetUserGetInfo request to the server to get the user's profiles location. However, the response does not have room for a separate profiles location field, only the user's home share. This means that Win9X profiles are restricted to being in the user's home directory.

WinNT clients send a NetSAMLogon RPC request, which contains many fields, including a separate field for the location of the user's profiles. This means that support for profiles is different for Win9X and WinNT.

Windows NT Configuration

To support WinNT clients, inn the [global] section of smb.conf set the following (for example):

logon path = \\profileserver\profileshare\profilepath\%U\moreprofilepath

The default for this option is \\%N\%U\profile, namely \\sambaserver\username\profile. The \\N%\%U service is created automatically by the [homes] service. If you are using a samba server for the profiles, you _must_ make the share specified in the logon path browseable.

Note: [lkcl 26aug96 - we have discovered a problem where Windows clients can maintain a connection to the [homes] share in between logins. The [homes] share must NOT therefore be used in a profile path.]

Windows 9X Configuration

To support Win9X clients, you must use the "logon home" parameter. Samba has now been fixed so that "net use/home" now works as well, and it, too, relies on the "logon home" parameter.

By using the logon home parameter, you are restricted to putting Win9X profiles in the user's home directory. But wait! There is a trick you can use. If you set the following in the [global] section of your smb.conf file:

logon home = \\%L\%U\.profiles

then your Win9X clients will dutifully put their clients in a subdirectory of your home directory called .profiles (thus making them hidden).

Not only that, but 'net use/home' will also work, because of a feature in Win9X. It removes any directory stuff off the end of the home directory area and only uses the server and share portion. That is, it looks like you specified \\%L\%U for "logon home".

Win9X and WinNT Configuration

You can support profiles for both Win9X and WinNT clients by setting both the "logon home" and "logon path" parameters. For example:

logon home = \\%L\%U\.profiles
logon path = \\%L\profiles\%U

Note: I have not checked what 'net use /home' does on NT when "logon home" is set as above.

Windows 9X Profile Setup

When a user first logs in on Windows 9X, the file user.DAT is created, as are folders "Start Menu", "Desktop", "Programs" and "Nethood". These directories and their contents will be merged with the local versions stored in c:\windows\profiles\username on subsequent logins, taking the most recent from each. You will need to use the [global] options "preserve case = yes", "short preserve case = yes" and "case sensitive = no" in order to maintain capital letters in shortcuts in any of the profile folders.

The user.DAT file contains all the user's preferences. If you wish to enforce a set of preferences, rename their user.DAT file to user.MAN, and deny them write access to this file.

  1. On the Windows 95 machine, go to Control Panel | Passwords and select the User Profiles tab. Select the required level of roaming preferences. Press OK, but do _not_ allow the computer to reboot.

  2. On the Windows 95 machine, go to Control Panel | Network | Client for Microsoft Networks | Preferences. Select 'Log on to NT Domain'. Then, ensure that the Primary Logon is 'Client for Microsoft Networks'. Press OK, and this time allow the computer to reboot.

Under Windows 95, Profiles are downloaded from the Primary Logon. If you have the Primary Logon as 'Client for Novell Networks', then the profiles and logon script will be downloaded from your Novell Server. If you have the Primary Logon as 'Windows Logon', then the profiles will be loaded from the local machine - a bit against the concept of roaming profiles, if you ask me.

You will now find that the Microsoft Networks Login box contains [user, password, domain] instead of just [user, password]. Type in the samba server's domain name (or any other domain known to exist, but bear in mind that the user will be authenticated against this domain and profiles downloaded from it, if that domain logon server supports it), user name and user's password.

Once the user has been successfully validated, the Windows 95 machine will inform you that 'The user has not logged on before' and asks you if you wish to save the user's preferences? Select 'yes'.

Once the Windows 95 client comes up with the desktop, you should be able to examine the contents of the directory specified in the "logon path" on the samba server and verify that the "Desktop", "Start Menu", "Programs" and "Nethood" folders have been created.

These folders will be cached locally on the client, and updated when the user logs off (if you haven't made them read-only by then :-). You will find that if the user creates further folders or short-cuts, that the client will merge the profile contents downloaded with the contents of the profile directory already on the local client, taking the newest folders and short-cuts from each set.

If you have made the folders / files read-only on the samba server, then you will get errors from the w95 machine on logon and logout, as it attempts to merge the local and the remote profile. Basically, if you have any errors reported by the w95 machine, check the unix file permissions and ownership rights on the profile directory contents, on the samba server.

If you have problems creating user profiles, you can reset the user's local desktop cache, as shown below. When this user then next logs in, they will be told that they are logging in "for the first time".

  1. instead of logging in under the [user, password, domain] dialog, press escape.

  2. run the regedit.exe program, and look in:

    HKEY_LOCAL_MACHINE\Windows\CurrentVersion\ProfileList

    you will find an entry, for each user, of ProfilePath. Note the contents of this key (likely to be c:\windows\profiles\username), then delete the key ProfilePath for the required user.

    [Exit the registry editor].

  3. WARNING - before deleting the contents of the directory listed in the ProfilePath (this is likely to be c:\windows\profiles\username), ask them if they have any important files stored on their desktop or in their start menu. delete the contents of the directory ProfilePath (making a backup if any of the files are needed).

    This will have the effect of removing the local (read-only hidden system file) user.DAT in their profile directory, as well as the local "desktop", "nethood", "start menu" and "programs" folders.

  4. search for the user's .PWL password-caching file in the c:\windows directory, and delete it.

  5. log off the windows 95 client.

  6. check the contents of the profile path (see "logon path" described above), and delete the user.DAT or user.MAN file for the user, making a backup if required.

If all else fails, increase samba's debug log levels to between 3 and 10, and / or run a packet trace program such as tcpdump or netmon.exe, and look for any error reports.

If you have access to an NT server, then first set up roaming profiles and / or netlogons on the NT server. Make a packet trace, or examine the example packet traces provided with NT server, and see what the differences are with the equivalent samba trace.

Windows NT Workstation 4.0

When a user first logs in to a Windows NT Workstation, the profile NTuser.DAT is created. The profile location can be now specified through the "logon path" parameter.

Note: [lkcl 10aug97 - i tried setting the path to \\samba-server\homes\profile, and discovered that this fails because a background process maintains the connection to the [homes] share which does _not_ close down in between user logins. you have to have \\samba-server\%L\profile, where user is the username created from the [homes] share].

There is a parameter that is now available for use with NT Profiles: "logon drive". This should be set to "h:" or any other drive, and should be used in conjunction with the new "logon home" parameter.

The entry for the NT 4.0 profile is a _directory_ not a file. The NT help on profiles mentions that a directory is also created with a .PDS extension. The user, while logging in, must have write permission to create the full profile path (and the folder with the .PDS extension) [lkcl 10aug97 - i found that the creation of the .PDS directory failed, and had to create these manually for each user, with a shell script. also, i presume, but have not tested, that the full profile path must be browseable just as it is for w95, due to the manner in which they attempt to create the full profile path: test existence of each path component; create path component].

In the profile directory, NT creates more folders than 95. It creates "Application Data" and others, as well as "Desktop", "Nethood", "Start Menu" and "Programs". The profile itself is stored in a file NTuser.DAT. Nothing appears to be stored in the .PDS directory, and its purpose is currently unknown.

You can use the System Control Panel to copy a local profile onto a samba server (see NT Help on profiles: it is also capable of firing up the correct location in the System Control Panel for you). The NT Help file also mentions that renaming NTuser.DAT to NTuser.MAN turns a profile into a mandatory one.

Note: [lkcl 10aug97 - i notice that NT Workstation tells me that it is downloading a profile from a slow link. whether this is actually the case, or whether there is some configuration issue, as yet unknown, that makes NT Workstation _think_ that the link is a slow one is a matter to be resolved].

[lkcl 20aug97 - after samba digest correspondence, one user found, and another confirmed, that profiles cannot be loaded from a samba server unless "security = user" and "encrypt passwords = yes" (see the file ENCRYPTION.txt) or "security = server" and "password server = ip.address. of.yourNTserver" are used. Either of these options will allow the NT workstation to access the samba server using LAN manager encrypted passwords, without the user intervention normally required by NT workstation for clear-text passwords].

[lkcl 25aug97 - more comments received about NT profiles: the case of the profile _matters_. the file _must_ be called NTuser.DAT or, for a mandatory profile, NTuser.MAN].

Windows NT Server

There is nothing to stop you specifying any path that you like for the location of users' profiles. Therefore, you could specify that the profile be stored on a samba server, or any other SMB server, as long as that SMB server supports encrypted passwords.

Sharing Profiles between W95 and NT Workstation 4.0

Potentially outdated or incorrect material follows

I think this is all bogus, but have not deleted it. (Richard Sharpe)

The default logon path is \\%N\U%. NT Workstation will attempt to create a directory "\\samba-server\username.PDS" if you specify the logon path as "\\samba-server\username" with the NT User Manager. Therefore, you will need to specify (for example) "\\samba-server\username\profile". NT 4.0 will attempt to create "\\samba-server\username\profile.PDS", which is more likely to succeed.

If you then want to share the same Start Menu / Desktop with W95, you will need to specify "logon path = \\samba-server\username\profile" [lkcl 10aug97 this has its drawbacks: i created a shortcut to telnet.exe, which attempts to run from the c:\winnt\system32 directory. this directory is obviously unlikely to exist on a Win95-only host].

If you have this set up correctly, you will find separate user.DAT and NTuser.DAT files in the same profile directory.

Note: [lkcl 25aug97 - there are some issues to resolve with downloading of NT profiles, probably to do with time/date stamps. i have found that NTuser.DAT is never updated on the workstation after the first time that it is copied to the local workstation profile directory. this is in contrast to w95, where it _does_ transfer / update profiles correctly].

DOMAIN_CONTROL.txt : Windows NT Domain Control & Samba

Possibly Outdated Material

This appendix was originally authored by John H Terpstra of the Samba Team and is included here for posterity.

NOTE : The term "Domain Controller" and those related to it refer to one specific method of authentication that can underly an SMB domain. Domain Controllers prior to Windows NT Server 3.1 were sold by various companies and based on private extensions to the LAN Manager 2.1 protocol. Windows NT introduced Microsoft-specific ways of distributing the user authentication database. See DOMAIN.txt for examples of how Samba can participate in or create SMB domains based on shared authentication database schemes other than the Windows NT SAM.

Windows NT Server can be installed as either a plain file and print server (WORKGROUP workstation or server) or as a server that participates in Domain Control (DOMAIN member, Primary Domain controller or Backup Domain controller). The same is true for OS/2 Warp Server, Digital Pathworks and other similar products, all of which can participate in Domain Control along with Windows NT.

To many people these terms can be confusing, so let's try to clear the air.

Every Windows NT system (workstation or server) has a registry database. The registry contains entries that describe the initialization information for all services (the equivalent of Unix Daemons) that run within the Windows NT environment. The registry also contains entries that tell application software where to find dynamically loadable libraries that they depend upon. In fact, the registry contains entries that describes everything that anything may need to know to interact with the rest of the system.

The registry files can be located on any Windows NT machine by opening a command prompt and typing:

C:\WINNT\> dir %SystemRoot%\System32\config

The environment variable %SystemRoot% value can be obtained by typing:

C:\WINNT>echo %SystemRoot%

The active parts of the registry that you may want to be familiar with are the files called: default, system, software, sam and security.

In a domain environment, Microsoft Windows NT domain controllers participate in replication of the SAM and SECURITY files so that all controllers within the domain have an exactly identical copy of each.

The Microsoft Windows NT system is structured within a security model that says that all applications and services must authenticate themselves before they can obtain permission from the security manager to do what they set out to do.

The Windows NT User database also resides within the registry. This part of the registry contains the user's security identifier, home directory, group memberships, desktop profile, and so on.

Every Windows NT system (workstation as well as server) will have its own registry. Windows NT Servers that participate in Domain Security control have a database that they share in common - thus they do NOT own an independent full registry database of their own, as do Workstations and plain Servers.

The User database is called the SAM (Security Access Manager) database and is used for all user authentication as well as for authentication of inter- process authentication (i.e. to ensure that the service action a user has requested is permitted within the limits of that user's privileges).

The Samba team have produced a utility that can dump the Windows NT SAM into smbpasswd format: see ENCRYPTION.txt for information on smbpasswd and /pub/samba/pwdump on your nearest Samba mirror for the utility. This facility is useful but cannot be easily used to implement SAM replication to Samba systems.

Windows for Workgroups, Windows 95, and Windows NT Workstations and Servers can participate in a Domain security system that is controlled by Windows NT servers that have been correctly configured. Almost every domain will have ONE Primary Domain Controller (PDC). It is desirable that each domain will have at least one Backup Domain Controller (BDC).

The PDC and BDCs then participate in replication of the SAM database so that each Domain Controlling participant will have an up to date SAM component within its registry.