This document describes how to use an LDAP directory for storing Samba user account information traditionally stored in the smbpasswd(5) file. It is assumed that the reader already has a basic understanding of LDAP concepts and has a working directory server already installed. For more information on LDAP architectures and Directories, please refer to the following sites.

Note that O'Reilly Publishing is working on a guide to LDAP for System Administrators which has a planned release date of early summer, 2002.

Two additional Samba resources which may prove to be helpful are

Traditionally, when configuring "encrypt passwords = yes" in Samba's smb.conf file, user account information such as username, LM/NT password hashes, password change times, and account flags have been stored in the smbpasswd(5) file. There are several disadvantages to this approach for sites with very large numbers of users (counted in the thousands).

As a result of these defeciencies, a more robust means of storing user attributes used by smbd was developed. The API which defines access to user accounts is commonly referred to as the samdb interface (previously this was called the passdb API, and is still so named in the CVS trees).

There are a few points to stress about that the ldapsam does not provide. The LDAP support referred to in the this documentation does not include:

The second item can be accomplished by using LDAP NSS and PAM modules. LGPL versions of these libraries can be obtained from PADL Software (http://www.padl.com/). More information about the configuration of these packages may be found at "LDAP, System Administration; Gerald Carter, O'Reilly; Chapter 6: Replacing NIS".

The LDAP samdb code in 2.2.3 (and later) has been developed and tested using the OpenLDAP 2.0 server and client libraries. The same code should be able to work with Netscape's Directory Server and client SDK. However, due to lack of testing so far, there are bound to be compile errors and bugs. These should not be hard to fix. If you are so inclined, please be sure to forward all patches to samba-patches@samba.org and jerry@samba.org.

Samba 3.0 includes the necessary schema file for OpenLDAP 2.0 in examples/LDAP/samba.schema. The sambaAccount objectclass is given here:

objectclass ( 1.3.1.5.1.4.1.7165.2.2.2 NAME 'sambaAccount' SUP top AUXILIARY
     DESC 'Samba Account'
     MUST ( uid $ rid )
     MAY  ( cn $ lmPassword $ ntPassword $ pwdLastSet $ logonTime $
            logoffTime $ kickoffTime $ pwdCanChange $ pwdMustChange $ acctFlags $
            displayName $ smbHome $ homeDrive $ scriptPath $ profilePath $
            description $ userWorkstations $ primaryGroupID $ domain ))

The samba.schema file has been formatted for OpenLDAP 2.0. The OID's are owned by the Samba Team and as such is legal to be openly published. If you translate the schema to be used with Netscape DS, please submit the modified schema file as a patch to jerry@samba.org

Just as the smbpasswd file is meant to store information which supplements a user's /etc/passwd entry, so is the sambaAccount object meant to supplement the UNIX user account information. A sambaAccount is a STRUCTURAL objectclass so it can be stored individually in the directory. However, there are several fields (e.g. uid) which overlap with the posixAccount objectclass outlined in RFC2307. This is by design.

In order to store all user account information (UNIX and Samba) in the directory, it is necessary to use the sambaAccount and posixAccount objectclasses in combination. However, smbd will still obtain the user's UNIX account information via the standard C library calls (e.g. getpwnam(), et. al.). This means that the Samba server must also have the LDAP NSS library installed and functioning correctly. This division of information makes it possible to store all Samba account information in LDAP, but still maintain UNIX account information in NIS while the network is transitioning to a full LDAP infrastructure.

As users accounts are managed thru the sambaAccount objectclass, you should modify your existing administration tools to deal with sambaAccount attributes.

Machines accounts are managed with the sambaAccount objectclass, just like users accounts. However, it's up to you to store thoses accounts in a different tree of you LDAP namespace: you should use "ou=Groups,dc=plainjoe,dc=org" to store groups and "ou=People,dc=plainjoe,dc=org" to store users. Just configure your NSS and PAM accordingly (usually, in the /etc/ldap.conf configuration file).

In Samba release 3.0, the group management system is based on posix groups. This means that Samba makes usage of the posixGroup objectclass. For now, there is no NT-like group system management (global and local groups).

There are two important points to remember when discussing the security of sambaAccount entries in the directory.

These password hashes are clear text equivalents and can be used to impersonate the user without deriving the original clear text strings. For more information on the details of LM/NT password hashes, refer to the User Database of the Samba-HOWTO-Collection.

To remedy the first security issue, the "ldap ssl" smb.conf parameter defaults to require an encrypted session (ldap ssl = on) using the default port of 636 when contacting the directory server. When using an OpenLDAP 2.0 server, it is possible to use the use the StartTLS LDAP extended operation in the place of LDAPS. In either case, you are strongly discouraged to disable this security (ldap ssl = off).

Note that the LDAPS protocol is deprecated in favor of the LDAPv3 StartTLS extended operation. However, the OpenLDAP library still provides support for the older method of securing communication between clients and servers.

The second security precaution is to prevent non-administrative users from harvesting password hashes from the directory. This can be done using the following ACL in slapd.conf:

## allow the "ldap admin dn" access, but deny everyone else
access to attrs=lmPassword,ntPassword
     by dn="cn=Samba Admin,ou=people,dc=plainjoe,dc=org" write
     by * none

The sambaAccount objectclass is composed of the following attributes:

The majority of these parameters are only used when Samba is acting as a PDC of a domain (refer to the Samba-PDC-HOWTO for details on how to configure Samba as a Primary Domain Controller). The following four attributes are only stored with the sambaAccount entry if the values are non-default values:

These attributes are only stored with the sambaAccount entry if the values are non-default values. For example, assume TASHTEGO has now been configured as a PDC and that logon home = \\%L\%u was defined in its smb.conf file. When a user named "becky" logons to the domain, the logon home string is expanded to \\TASHTEGO\becky. If the smbHome attribute exists in the entry "uid=becky,ou=people,dc=samba,dc=org", this value is used. However, if this attribute does not exist, then the value of the logon home parameter is used in its place. Samba will only write the attribute value to the directory entry if the value is something other than the default (e.g. \\MOBY\becky).

The following is a working LDIF with the inclusion of the posixAccount objectclass:

dn: uid=guest2, ou=people,dc=plainjoe,dc=org
ntPassword: 878D8014606CDA29677A44EFA1353FC7
pwdMustChange: 2147483647
primaryGroupID: 1201
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
pwdLastSet: 1010179124
logonTime: 0
objectClass: sambaAccount
uid: guest2
kickoffTime: 2147483647
acctFlags: [UX         ]
logoffTime: 2147483647
rid: 19006
pwdCanChange: 0

The following is an LDIF entry for using both the sambaAccount and posixAccount objectclasses:

dn: uid=gcarter, ou=people,dc=plainjoe,dc=org
logonTime: 0
displayName: Gerald Carter
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
primaryGroupID: 1201
objectClass: posixAccount
objectClass: sambaAccount
acctFlags: [UX         ]
userPassword: {crypt}BpM2ej8Rkzogo
uid: gcarter
uidNumber: 9000
cn: Gerald Carter
loginShell: /bin/bash
logoffTime: 2147483647
gidNumber: 100
kickoffTime: 2147483647
pwdLastSet: 1010179230
rid: 19000
homeDirectory: /home/tashtego/gcarter
pwdCanChange: 0
pwdMustChange: 2147483647
ntPassword: 878D8014606CDA29677A44EFA1353FC7

You either can set up your own table and specify the field names to pdb_mysql (see below for the column names) or use the default table. The file examples/pdb/mysql/mysql.dump contains the correct queries to create the required tables. Use the command : mysql -uusername -hhostname -ppassword databasename > /path/to/samba/examples/pdb/mysql/mysql.dump

This plugin lacks some good documentation, but here is some short info:

Add a the following to the passdb backend variable in your smb.conf:

passdb backend = [other-plugins] mysql:identifier [other-plugins]

The identifier can be any string you like, as long as it doesn't collide with the identifiers of other plugins or other instances of pdb_mysql. If you specify multiple pdb_mysql.so entries in 'passdb backend', you also need to use different identifiers!

Additional options can be given thru the smb.conf file in the [global] section.

identifier:mysql host                     - host name, defaults to 'localhost'
identifier:mysql password
identifier:mysql user                     - defaults to 'samba'
identifier:mysql database                 - defaults to 'samba'
identifier:mysql port                     - defaults to 3306
identifier:table                          - Name of the table containing users

Names of the columns in this table(I've added column types those columns should have first):

identifier:logon time column             - int(9)
identifier:logoff time column            - int(9)
identifier:kickoff time column           - int(9)
identifier:pass last set time column     - int(9)
identifier:pass can change time column   - int(9)
identifier:pass must change time column  - int(9)
identifier:username column               - varchar(255) - unix username
identifier:domain column                 - varchar(255) - NT domain user is part of
identifier:nt username column            - varchar(255) - NT username
identifier:fullname column               - varchar(255) - Full name of user
identifier:home dir column               - varchar(255) - Unix homedir path
identifier:dir drive column              - varchar(2)   - Directory drive path (eg: 'H:')
identifier:logon script column           - varchar(255)
					 - Batch file to run on client side when logging on
identifier:profile path column           - varchar(255) - Path of profile
identifier:acct desc column              - varchar(255) - Some ASCII NT user data
identifier:workstations column           - varchar(255)
					 - Workstations user can logon to (or NULL for all)
identifier:unknown string column         - varchar(255) - unknown string
identifier:munged dial column            - varchar(255) - ?
identifier:user sid column               - varchar(255) - NT user SID
identifier:group sid column              - varchar(255) - NT group ID
identifier:lanman pass column            - varchar(255) - encrypted lanman password
identifier:nt pass column                - varchar(255) - encrypted nt passwd
identifier:plain pass column             - varchar(255) - plaintext password
identifier:acct control column           - int(9) - nt user data
identifier:unknown 3 column              - int(9) - unknown
identifier:logon divs column             - int(9) - ?
identifier:hours len column              - int(9) - ?
identifier:unknown 5 column              - int(9) - unknown
identifier:unknown 6 column              - int(9) - unknown

Eventually, you can put a colon (:) after the name of each column, which should specify the column to update when updating the table. You can also specify nothing behind the colon - then the data from the field will not be updated.

I strongly discourage the use of plaintext passwords, however, you can use them:

If you would like to use plaintext passwords, set 'identifier:lanman pass column' and 'identifier:nt pass column' to 'NULL' (without the quotes) and 'identifier:plain pass column' to the name of the column containing the plaintext passwords.

If you use encrypted passwords, set the 'identifier:plain pass column' to 'NULL' (without the quotes). This is the default.

It is possible to have not all data in the database and making some 'constant'.

For example, you can set 'identifier:fullname column' to : CONCAT(First_name,' ',Sur_name)

Or, set 'identifier:workstations column' to : NULL

See the MySQL documentation for more language constructs.