&author.jelmer; &author.jht; &author.jerry; &author.jeremy; &person.gd;LDAP updates Olivier (lem)Lemaire IDEALX

olem@IDEALX.org

May 24, 2003 account backends password backends scalability ADS Samba-3 implements a new capability to work concurrently with multiple account backends. The possible new combinations of password backends allows Samba-3 a degree of flexibility and scalability that previously could be achieved only with MS Windows Active Directory (ADS). This chapter describes the new functionality and how to get the most out of it. passdb backend smbpasswd tdbsam ldapsam LDAP single repository The three passdb backends that are fully maintained (actively supported) by the Samba Team are: smbpasswd (being obsoleted), tdbsam (a tdb based binary file format), and ldapsam (LDAP directory). Of these, only the ldapsam backend stores both POSIX (UNIX) and Samba user and group account information in a single repository. The smbpasswd and tdbsam backends store only Samba user accounts. In a strict sense, there are three supported account storage and access systems. One of these is considered obsolete (smbpasswd). It is recommended to use tdbsam method for all simple systems. Use the ldapsam for larger and more complex networks. passdb backend account storage mechanisms account storage system user and trust accounts machine trust accounts computer accounts interdomain trust accounts In a strict and literal sense, the passdb backends are account storage mechanisms (or methods) alone. The choice of terminology can be misleading, however we are stuck with this choice of wording. This chapter documents the nature of the account storage system with a focus on user and trust accounts. Trust accounts have two forms, machine trust accounts (computer accounts) and interdomain trust accounts. These are all treated as user-like entities. Samba-3 provides for complete backward compatibility with Samba-2.2.x functionality as follows: SAM backendsmbpasswd SAM backendldapsam_compat encrypted passwords Plaintext plaintext plaintext authentication /etc/passwd /etc/shadow PAM This isn't really a backend at all, but is listed here for simplicity. Samba can be configured to pass plaintext authentication requests to the traditional UNIX/Linux /etc/passwd and /etc/shadow-style subsystems. On systems that have Pluggable Authentication Modules (PAM) support, all PAM modules are supported. The behavior is just as it was with Samba-2.2.x, and the protocol limitations imposed by MS Windows clients apply likewise. Please refer to Technical Information, for more information regarding the limitations of plaintext password usage. smbpasswd smbpasswd LanMan passwords NT-encrypted passwords SAM This option allows continued use of the smbpasswd file that maintains a plain ASCII (text) layout that includes the MS Windows LanMan and NT-encrypted passwords as well as a field that stores some account information. This form of password backend does not store any of the MS Windows NT/200x SAM (Security Account Manager) information required to provide the extended controls that are needed for more comprehensive interoperation with MS Windows NT4/200x servers. This backend should be used only for backward compatibility with older versions of Samba. It may be deprecated in future releases. ldapsam_compat (Samba-2.2 LDAP Compatibility) ldapsam_compat Samba-2.2.x LDAP schema OpenLDAP backend There is a password backend option that allows continued operation with an existing OpenLDAP backend that uses the Samba-2.2.x LDAP schema extension. This option is provided primarily as a migration tool, although there is no reason to force migration at this time. This tool will eventually be deprecated. Samba-3 introduces a number of new password backend capabilities. SAM backendtdbsam SAM backendldapsam SAM backendmysqlsam SAM backendxmlsam tdbsam rich database backend PDC BDC This backend provides a rich database backend for local servers. This backend is not suitable for multiple domain controllers (i.e., PDC + one or more BDC) installations. extended SAM TDB binary format TDB trivial database system access controls MS Windows NT4/200x The tdbsam password backend stores the old smbpasswd information plus the extended MS Windows NT/200x SAM information into a binary format TDB (trivial database) file. The inclusion of the extended information makes it possible for Samba-3 to implement the same account and system access controls that are possible with MS Windows NT4/200x-based systems. simple operation OpenLDAP ADS The inclusion of the tdbsam capability is a direct response to user requests to allow simple site operation without the overhead of the complexities of running OpenLDAP. It is recommended to use this only for sites that have fewer than 250 users. For larger sites or implementations, the use of OpenLDAP or of Active Directory integration is strongly recommended. ldapsam rich directory backend distributed account This provides a rich directory backend for distributed account installation. LDAP OpenLDAP Samba schema schema file examples/LDAP Samba-3 has a new and extended LDAP implementation that requires configuration of OpenLDAP with a new format Samba schema. The new format schema file is included in the examples/LDAP directory of the Samba distribution. expands control abilities profile home directories account access controls greater scalability The new LDAP implementation significantly expands the control abilities that were possible with prior versions of Samba. It is now possible to specify per-user profile settings, home directories, account access controls, and much more. Corporate sites will see that the Samba Team has listened to their requests both for capability and greater scalability. mysqlsam (MySQL-based backend) MySQL-based SAM database backend It is expected that the MySQL-based SAM will be very popular in some corners. This database backend will be of considerable interest to sites that want to leverage existing MySQL technology. pgsqlsam (PostGreSQL-based backend) PostgreSQL database mysqlsam Stores user information in a PostgreSQL database. This backend is largely undocumented at the moment, though its configuration is very similar to that of the mysqlsam backend. xmlsam (XML-based datafile) pdbedit XML format pdb2pdb Allows the account and password data to be stored in an XML format data file. This backend cannot be used for normal operation, it can only be used in conjunction with pdbedit's pdb2pdb functionality. The Document Type Definition (DTD) file that is used might be subject to changes in the future. (See the XML reference for a definition of XML terms.) account migration database backends backend format The xmlsam option can be useful for account migration between database backends or backups. Use of this tool allows the data to be edited before migration into another backend format. plaintext passwords encrypted passwords Old Windows clients send plaintext passwords over the wire. Samba can check these passwords by encrypting them and comparing them to the hash stored in the UNIX user database. encrypted passwords LanMan plaintext passwords registry Newer Windows clients send encrypted passwords (LanMan and NT hashes) instead of plaintext passwords over the wire. The newest clients will send only encrypted passwords and refuse to send plaintext passwords unless their registry is tweaked. UNIX-style encrypted passwords converted Many people ask why Samba can not simply use the UNIX password database. Windows requires passwords that are encrypted in its own format. The UNIX passwords can't be converted to UNIX-style encrypted passwords. Because of that, you can't use the standard UNIX user database, and you have to store the LanMan and NT hashes somewhere else. differently encrypted passwords profile workstations tdbsam In addition to differently encrypted passwords, Windows also stores certain data for each user that is not stored in a UNIX user database: for example, workstations the user may logon from, the location where the user's profile is stored, and so on. Samba retrieves and stores this information using a . Commonly available backends are LDAP, tdbsam, plain text file, and MySQL. For more information, see the man page for &smb.conf; regarding the parameter.

idmap-sid2uid

SID UID SID The resolution of SIDs to UIDs is fundamental to correct operation of Samba. In both cases shown, if winbindd is not running or cannot be contacted, then only local SID/UID resolution is possible. See resolution of SIDs to UIDs and resolution of UIDs to SIDs diagrams.

idmap-uid2sid

SMB password encryption clear-text passwords hashed password equivalent LDAP MYSQL secret The UNIX and SMB password encryption techniques seem similar on the surface. This similarity is, however, only skin deep. The UNIX scheme typically sends clear-text passwords over the network when logging in. This is bad. The SMB encryption scheme never sends the clear-text password over the network, but it does store the 16-byte hashed values on disk. This is also bad. Why? Because the 16 byte hashed values are a password equivalent. You cannot derive the user's password from them, but they could potentially be used in a modified client to gain access to a server. This would require considerable technical knowledge on behalf of the attacker but is perfectly possible. You should therefore treat the data stored in whatever passdb backend you use (smbpasswd file, LDAP, MYSQL) as though it contained the clear-text passwords of all your users. Its contents must be kept secret, and the file should be protected accordingly. password scheme plaintext passwords compatible Ideally, we would like a password scheme that involves neither plaintext passwords on the network nor plaintext passwords on disk. Unfortunately, this is not available because Samba is stuck with having to be compatible with other SMB systems (Windows NT, Windows for Workgroups, Windows 9x/Me). encrypted passwords plaintext passwords Windows NT 4.0 Service Pack 3 changed the default setting so plaintext passwords are disabled from being sent over the wire. This mandates either the use of encrypted password support or editing the Windows NT registry to re-enable plaintext passwords. domain security domain environment The following versions of Microsoft Windows do not support full domain security protocols, although they may log onto a domain environment: MS DOS Network client 3.0 with the basic network redirector installed. Windows 95 with the network redirector update installed. Windows 98 [Second Edition]. Windows Me. Windows XP Home domain member domain logons MS Windows XP Home does not have facilities to become a domain member, and it cannot participate in domain logons. The following versions of MS Windows fully support domain security protocols. Windows NT 3.5x. Windows NT 4.0. Windows 2000 Professional. Windows 200x Server/Advanced Server. Windows XP Professional. SMB/CIFS authentication challenge/response mechanis clear-text encrypted negotiate All current releases of Microsoft SMB/CIFS clients support authentication via the SMB challenge/response mechanism described here. Enabling clear-text authentication does not disable the ability of the client to participate in encrypted authentication. Instead, it allows the client to negotiate either plaintext or encrypted password handling. cached encrypted password plaintext passwords registry change auto-reconnect encrypted passwords MS Windows clients will cache the encrypted password alone. Where plaintext passwords are re-enabled through the appropriate registry change, the plaintext password is never cached. This means that in the event that a network connections should become disconnected (broken), only the cached (encrypted) password will be sent to the resource server to effect an auto-reconnect. If the resource server does not support encrypted passwords, the auto-reconnect will fail. Use of encrypted passwords is strongly advised. passed across the network network sniffer SMB server Plaintext passwords are not passed across the network. Someone using a network sniffer cannot just record passwords going to the SMB server. not stored anywhere memory disk Plaintext passwords are not stored anywhere in memory or on disk. encrypted passwords user-level security password prompt SMB encryption Windows NT does not like talking to a server that does not support encrypted passwords. It will refuse to browse the server if the server is also in user-level security mode. It will insist on prompting the user for the password on each connection, which is very annoying. The only thing you can do to stop this is to use SMB encryption. encrypted password automatic reconnects Encrypted password support allows automatic share (resource) reconnects. PDC BDC Encrypted passwords are essential for PDC/BDC operation. cached in memory Plaintext passwords are not kept on disk and are not cached in memory. Login FTP Plaintext passwords use the same password file as other UNIX services, such as Login and FTP. Telnet FTP Use of other services (such as Telnet and FTP) that send plaintext passwords over the network makes sending them for SMB is not such a big deal. UID SID mapping Every operation in UNIX/Linux requires a user identifier (UID), just as in MS Windows NT4/200x this requires a security identifier (SID). Samba provides two means for mapping an MS Windows user to a UNIX/Linux UID. Samba SAM SAM UID account information database local user account First, all Samba SAM database accounts require a UNIX/Linux UID that the account will map to. As users are added to the account information database, Samba will call the interface to add the account to the Samba host OS. In essence all accounts in the local SAM require a local user account. idmap uid idmap gid UID SAM foreign domain non-member Windows client SID The second way to map Windows SID to UNIX UID is via the idmap uid and idmap gid parameters in &smb.conf;. Please refer to the man page for information about these parameters. These parameters are essential when mapping users from a remote (non-member Windows client or a member of a foreign domain) SAM server. UID GID BDC domain member servers NFS rsync Samba-3 has a special facility that makes it possible to maintain identical UIDs and GIDs on all servers in a distributed network. A distributed network is one where there exists a PDC, one or more BDCs, and/or one or more domain member servers. Why is this important? This is important if files are being shared over more than one protocol (e.g., NFS) and where users are copying files across UNIX/Linux systems using tools such as rsync. LDAP-based idmap backend UID GID LDAP SAM backend LDAP idmap Backend idmap backend The special facility is enabled using a parameter called idmap backend. The default setting for this parameter is an empty string. Technically it is possible to use an LDAP-based idmap backend for UIDs and GIDs, but it makes most sense when this is done for network configurations that also use LDAP for the SAM backend. Example Configuration with the LDAP idmap Backend shows that configuration. SAM backendldapsam ldap:ldap://ldap-server.quenya.org:636 Alternatively, this could be specified as: ldap:ldaps://ldap-server.quenya.org LDAP backends PADL Software A network administrator who wants to make significant use of LDAP backends will sooner or later be exposed to the excellent work done by PADL Software. PADL have produced and released to open source an array of tools that might be of interest. These tools include: nss_ldap NSS AIX Linux LDAP Solaris UID GID nss_ldap: An LDAP name service switch (NSS) module to provide native name service support for AIX, Linux, Solaris, and other operating systems. This tool can be used for centralized storage and retrieval of UIDs and GIDs. pam_ldap PAM LDAP access authentication pam_ldap: A PAM module that provides LDAP integration for UNIX/Linux system access authentication. idmap_ad IDMAP backend RFC 2307 PADL idmap_ad: An IDMAP backend that supports the Microsoft Services for UNIX RFC 2307 schema available from the PADL Web site. LDAPdirectories architecture FIM SSO There is much excitement and interest in LDAP directories in the information technology world today. The LDAP architecture was designed to be highly scalable. It was also designed for use across a huge number of potential areas of application encompasing a wide range of operating systems and platforms. LDAP technologies are at the heart of the current generations of Federated Identity Management (FIM) solutions that can underlie a corporate Single Sign-On (SSO) environment. LDAP eDirectory ADS authentication LDAP implementations have been built across a wide variety of platforms. It lies at the core of Microsoft Windows Active Directory services (ADS), Novell's eDirectory, as well as many others. Implementation of the directory services LDAP involves interaction with legacy as well as new generation applications, all of which depend on some form of authentication services. LDAP directory authentication access controls intermediate tools middle-ware central environment infrastructure login shells mail messaging systems quota controls printing systems DNS servers DHCP servers UNIX services can utilize LDAP directory information for authentication and access controls through intermediate tools and utilities. The total environment that consists of the LDAP directory and the middle-ware tools and utilities makes it possible for all user access to the UNIX platform to be managed from a central environment and yet distributed to wherever the point of need may be physically located. Applications that benefit from this infrastructure include: UNIX login shells, mail and messaging systems, quota controls, printing systems, DNS servers, DHCP servers, and also Samba. LDAP passdb backend scalable SAM backend LDAP directory management costs Many sites are installing LDAP for the first time in order to provide a scalable passdb backend for Samba. Others are faced with the need to adapt an existing LDAP directory to new uses such as for the Samba SAM backend. Whatever your particular need and attraction to Samba may be, decisions made in respect of the design of the LDAP directory structure and its implementation are of a durable nature for the site. These have far-reaching implications that affect long term information systems management costs. LDAP deployment Directory Information TreeDIT Do not rush into an LDAP deployment. Take the time to understand how the design of the Directory Information Tree (DIT) may impact current and future site needs, as well as the ability to meet them. The way that Samba SAM information should be stored within the DIT varies from site to site and with each implementation new experience is gained. It is well understood by LDAP veterans that first implementation create awakening, second implementations of LDAP create fear, and third-generation deployments bring peace and tranquility. POSIX identity networking environment user accounts group accounts machine trust accounts interdomain trust accounts intermediate information Samba requires UNIX POSIX identity information as well as a place to store information that is specific to Samba and the Windows networking environment. The most used information that must be dealt with includes: user accounts, group accounts, machine trust accounts, interdomain trust accounts, and intermediate information specific to Samba internals. deployment guidelines HOWTO documents LDAP The example deployment guidelines in this book, as well as other books and HOWTO documents available from the internet may not fit with established directory designs and implementations. The existing DIT may not be able to accomodate the simple information layout proposed in common sources. Additionally, you may find that the common scripts and tools that are used to provision the LDAP directory for use with Samba may not suit your needs. existing LDAP DIT It is not uncommon, for sites that have existing LDAP DITs to find necessity to generate a set of site specific scripts and utilities to make it possible to deploy Samba within the scope of site operations. The way that user and group accounts are distributed throughout the DIT may make this a challenging matter. The solution will of course be rewarding, but the journey to it may be challenging. Take time to understand site needs and do not rush into deployment. scripts tools Above all, do not blindly use scripts and tools that are not suitable for your site. Check and validate all scripts before you execute them to make sure that the existing infrastructure will not be damaged by inadvertent use of an inappropriate tool. turnkey solution LDAP. frustrating experience Samba doesn't provide a turnkey solution to LDAP. It is best to deal with the design and configuration of an LDAP directory prior to integration with Samba. A working knowledge of LDAP makes Samba integration easy, and the lack of a working knowledge of LDAP can make it a frustrating experience. computer accounts machine accounts LDAP Computer (machine) accounts can be placed wherever you like in an LDAP directory subject to some constraints that are described in this chapter. POSIX sambaSamAccount computer accounts machine accounts Windows NT4/200X user account trust accounts The POSIX and sambaSamAccount components of computer (machine) accounts are both used by Samba. Thus, machine accounts are treated inside Samba in the same way that Windows NT4/200X treats them. A user account and a machine account are indistinquishable from each other, except that the machine account ends in a $ character, as do trust accounts. user group machine trust UID The need for Windows user, group, machine, trust, and other accounts to be tied to a valid UNIX UID is a design decision that was made a long way back in the history of Samba development. It is unlikely that this decision will be reversed or changed during the remaining life of the Samba-3.x series. UID SID NSS The resolution of a UID from the Windows SID is achieved within Samba through a mechanism that must refer back to the host operating system on which Samba is running. The NSS is the preferred mechanism that shields applications (like Samba) from the need to know everything about every host OS it runs on. UID passwd shadow group NSS winbindd LDAP Samba asks the host OS to provide a UID via the passwd, shadow, and group facilities in the NSS control (configuration) file. The best tool for achieving this is left up to the UNIX administrator to determine. It is not imposed by Samba. Samba provides winbindd with its support libraries as one method. It is possible to do this via LDAP, and for that Samba provides the appropriate hooks so that all account entities can be located in an LDAP directory. PADL nss_ldap UID LDAP documentation For many the weapon of choice is to use the PADL nss_ldap utility. This utility must be configured so that computer accounts can be resolved to a POSIX/UNIX account UID. That is fundamentally an LDAP design question. The information provided on the Samba list and in the documentation is directed at providing working examples only. The design of an LDAP directory is a complex subject that is beyond the scope of this documentation. pdbedit machine accounts management tools Samba provides two tools for management of user and machine accounts: smbpasswd and pdbedit. pdbedit password aging failed logins The pdbedit can be used to manage account policies in addition to Samba user account information. The policy management capability is used to administer domain default settings for password aging and management controls to handle failed login attempts. smbpasswd storage mechanism SambaSAMAccount net Some people are confused when reference is made to smbpasswd because the name refers to a storage mechanism for SambaSAMAccount information, but it is also the name of a utility tool. That tool is destined to eventually be replaced by new functionality that is being added to the net toolset (see the Net Command. smbpasswd passwd yppasswd passdb backend storage methods The smbpasswd utility is similar to the passwd and yppasswd programs. It maintains the two 32 byte password fields in the passdb backend. This utility operates independantly of the actual account and password storage methods used (as specified by the passdb backend in the &smb.conf; file. smbpasswd client-server mode smbpasswd works in a client-server mode where it contacts the local smbd to change the user's password on its behalf. This has enormous benefits. smbpasswd change passwords smbpasswd has the capability to change passwords on Windows NT servers (this only works when the request is sent to the NT PDC if changing an NT domain user's password). user management user accountAdding/Deleting smbpasswd can be used to: add user or machine accounts. delete user or machine accounts. enable user or machine accounts. disable user or machine accounts. set to NULL user passwords. manage interdomain trust accounts. To run smbpasswd as a normal user, just type: &prompt;smbpasswd Old SMB password: secret For secret, type the old value here or press return if there is no old password. New SMB Password: new secret Repeat New SMB Password: new secret If the old value does not match the current value stored for that user, or the two new values do not match each other, then the password will not be changed. SMB password When invoked by an ordinary user, the command will allow only the user to change his or her own SMB password. smbpasswd SMB password When run by root, smbpasswd may take an optional argument specifying the username whose SMB password you wish to change. When run as root, smbpasswd does not prompt for or check the old password value, thus allowing root to set passwords for users who have forgotten their passwords. smbpasswd passwd yppasswd change capabilities smbpasswd is designed to work in the way familiar to UNIX users who use the passwd or yppasswd commands. While designed for administrative use, this tool provides essential user-level password change capabilities. smbpasswd For more details on using smbpasswd, refer to the man page (the definitive reference). pdbedit User Management User AccountsAdding/Deleting pdbedit is a tool that can be used only by root. It is used to manage the passdb backend. pdbedit can be used to: add, remove, or modify user accounts. list user accounts. migrate user accounts. Domain global policy controls available include: Maximum Password Age Minimum Password Age Mimimum Password Length Password Uniqueness (remembers number of prior passwords) Account Lockout Bad Logon Attempts Lockout Reset Delay Lockout Duration pdbedit policy settings account security smbpasswd The pdbedit tool is the only one that can manage the account security and policy settings. It is capable of all operations that smbpasswd can do as well as a superset of them. pdbedit account migration passdb backend One particularly important purpose of the pdbedit is to allow the migration of account information from one passdb backend to another. See the XML password backend section of this chapter. tdbsam The following is an example of the user account information that is stored in a tdbsam password backend. This listing was produced by running: &prompt;pdbedit -Lv met UNIX username: met NT username: Account Flags: [UX ] User SID: S-1-5-21-1449123459-1407424037-3116680435-2004 Primary Group SID: S-1-5-21-1449123459-1407424037-3116680435-1201 Full Name: Melissa E Terpstra Home Directory: \\frodo\met\Win9Profile HomeDir Drive: H: Logon Script: scripts\logon.bat Profile Path: \\frodo\Profiles\met Domain: &example.workgroup; Account desc: Workstations: melbelle Munged dial: Logon time: 0 Logoff time: Mon, 18 Jan 2038 20:14:07 GMT Kickoff time: Mon, 18 Jan 2038 20:14:07 GMT Password last set: Sat, 14 Dec 2002 14:37:03 GMT Password can change: Sat, 14 Dec 2002 14:37:03 GMT Password must change: Mon, 18 Jan 2038 20:14:07 GMT pdbedit migrate accounts authentication The pdbedit tool allows migration of authentication (account) databases from one backend to another. For example, to migrate accounts from an old smbpasswd database to a tdbsam backend: Set the tdbsam, smbpasswd. pdbedit Execute: &rootprompt;pdbedit -i smbpasswd -e tdbsam smbpasswd Remove the smbpasswd from the passdb backend configuration in &smb.conf;. account database SMB/CIFS server Samba offers the greatest flexibility in backend account database design of any SMB/CIFS server technology available today. The flexibility is immediately obvious as one begins to explore this capability. multiple backends tdbsam databases It is possible to specify not only multiple password backends, but even multiple backends of the same type. For example, to use two different tdbsam databases: tdbsam:/etc/samba/passdb.tdb tdbsam:/etc/samba/old-passdb.tdb What is possible, is not always sensible. Be careful to avoid complexity to the point that it may be said that the solution is too clever by half! user database /etc/samba/smbpasswd /etc/smbpasswd password encryption /etc/passwd PAM Older versions of Samba retrieved user information from the UNIX user database and eventually some other fields from the file /etc/samba/smbpasswd or /etc/smbpasswd. When password encryption is disabled, no SMB-specific data is stored at all. Instead, all operations are conducted via the way that the Samba host OS will access its /etc/passwd database. On most Linux systems, for example, all user and group resolution is done via PAM. SAM backendsmbpasswd user account LM/NT password hashes smbpasswd Traditionally, when configuring 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 large numbers of users (counted in the thousands). lookups The first problem is that all lookups must be performed sequentially. Given that there are approximately two lookups per domain logon (one during intial logon validation and one for a session connection setup, such as when mapping a network drive or printer), this is a performance bottleneck for large sites. What is needed is an indexed approach such as used in databases. smbpasswd replicate rsync ssh custom scripts The second problem is that administrators who desire to replicate an smbpasswd file to more than one Samba server are left to use external tools such as rsync(1) and ssh(1) and write custom, in-house scripts. smbpasswd home directory password expiration relative identifier relative identifierRID Finally, the amount of information that is stored in an smbpasswd entry leaves no room for additional attributes such as a home directory, password expiration time, or even a relative identifier (RID). user attributes smbd API samdb interface As a result of these deficiencies, a more robust means of storing user attributes used by smbd was developed. The API that 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 Samba source code trees). passdb backends smbpasswd plaintext database tdbsam ldapsam xmlsam enterprise Samba provides an enhanced set of passdb backends that overcome the deficiencies of the smbpasswd plaintext database. These are tdbsam, ldapsam, and xmlsam. Of these, ldapsam will be of most interest to large corporate or enterprise sites. SAM backendtdbsam trivial databaseTDB machine account Samba can store user and machine account data in a TDB (trivial database). Using this backend does not require any additional configuration. This backend is recommended for new installations that do not require LDAP. tdbsam PDC BDC scalability As a general guide, the Samba Team does not recommend using the tdbsam backend for sites that have 250 or more users. Additionally, tdbsam is not capable of scaling for use in sites that require PDB/BDC implementations that require replication of the account database. Clearly, for reason of scalability, the use of ldapsam should be encouraged. 250-user limit performance-based tdbsam The recommendation of a 250-user limit is purely based on the notion that this would generally involve a site that has routed networks, possibly spread across more than one physical location. The Samba Team has not at this time established the performance-based scalability limits of the tdbsam architecture. 4,500 user accounts passdb backend tdbsam SambaSAMAccount There are sites that have thousands of users and yet require only one server. One site recently reported having 4,500 user accounts on one UNIX system and reported excellent performance with the tdbsam passdb backend. The limitation of where the tdbsam passdb backend can be used is not one pertaining to a limitation in the TDB storage system, it is based only on the need for a reliable distribution mechanism for the SambaSAMAccount backend. LDAP ldapsam SAM backendldapsam There are a few points to stress that the ldapsam does not provide. The LDAP support referred to in this documentation does not include: A means of retrieving user account information from a Windows 200x Active Directory server. A means of replacing /etc/passwd. LDAP NSS PAM LGPL The second item can be accomplished by using LDAP NSS and PAM modules. LGPL versions of these libraries can be obtained from PADL Software. More information about the configuration of these packages may be found in LDAP, System Administration by Gerald Carter, Chapter 6, Replacing NIS". LDAP directory smbpasswd directory server 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: OpenLDAP Sun One Directory Server Novell eDirectory IBM Tivoli Directory Server Red Hat Directory Server Fedora Directory Server Two additional Samba resources that may prove to be helpful are: Samba-PDC-LDAP-HOWTO The Samba-PDC-LDAP-HOWTO maintained by Ignacio Coupeau. IDEALX NT migration scripts smbldap-tools The NT migration scripts from IDEALX that are geared to manage users and groups in such a Samba-LDAP domain controller configuration. Idealx also produced the smbldap-tools and the Interactive Console Management tool. LDAP ldapsam OpenLDAP Netscape's Directory Server The LDAP ldapsam code was developed and tested using the OpenLDAP 2.x server and client libraries. The same code should work with Netscape's Directory Server and client SDK. However, there are bound to be compile errors and bugs. These should not be hard to fix. Please submit fixes via the process outlined in Reporting Bugs. Samba is capable of working with any standards compliant LDAP server. Samba-3.0 includes the necessary schema file for OpenLDAP 2.x in examples/LDAP/samba.schema directory of the source code distribution tarball. The schema entry for the sambaSamAccount ObjectClass is shown here: ObjectClass (1.3.6.1.4.1.7165.2.2.6 NAME 'sambaSamAccount' SUP top AUXILIARY DESC 'Samba-3.0 Auxiliary SAM Account' MUST ( uid $ sambaSID ) MAY ( cn $ sambaLMPassword $ sambaNTPassword $ sambaPwdLastSet $ sambaLogonTime $ sambaLogoffTime $ sambaKickoffTime $ sambaPwdCanChange $ sambaPwdMustChange $ sambaAcctFlags $ displayName $ sambaHomePath $ sambaHomeDrive $ sambaLogonScript $ sambaProfilePath $ description $ sambaUserWorkstations $ sambaPrimaryGroupSID $ sambaDomainName )) samba.schema OpenLDAP OID The samba.schema file has been formatted for OpenLDAP 2.0/2.1. The Samba Team owns the OID space used by the above schema and recommends its use. If you translate the schema to be used with Netscape DS, please submit the modified schema file as a patch to jerry@samba.org. smbpasswd /etc/passwd sambaSamAccount AUXILIARY ObjectClass LDAP RFC 2307. Just as the smbpasswd file is meant to store information that provides information additional to a user's /etc/passwd entry, so is the sambaSamAccount object meant to supplement the UNIX user account information. A sambaSamAccount is an AUXILIARY ObjectClass, so it can be used to augment existing user account information in the LDAP directory, thus providing information needed for Samba account handling. However, there are several fields (e.g., uid) that overlap with the posixAccount ObjectClass outlined in RFC 2307. This is by design. account information sambaSamAccount posixAccount ObjectClasses smbd getpwnam LDAP NIS NSS In order to store all user account information (UNIX and Samba) in the directory, it is necessary to use the sambaSamAccount and posixAccount ObjectClasses in combination. However, smbd will still obtain the user's UNIX account information via the standard C library calls, such as getpwnam(). 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. sambaSamAccount OpenLDAP slapd samba.schema To include support for the sambaSamAccount object in an OpenLDAP directory server, first copy the samba.schema file to slapd's configuration directory. The samba.schema file can be found in the directory examples/LDAP in the Samba source distribution. &rootprompt;cp samba.schema /etc/openldap/schema/ samba.schema slapd.conf sambaSamAccount cosine.schema uid inetorgperson.schema displayName attribute Next, include the samba.schema file in slapd.conf. The sambaSamAccount object contains two attributes that depend on other schema files. The uid attribute is defined in cosine.schema and the displayName attribute is defined in the inetorgperson.schema file. Both of these must be included before the samba.schema file. ## /etc/openldap/slapd.conf ## schema files (core.schema is required by default) include /etc/openldap/schema/core.schema ## needed for sambaSamAccount include /etc/openldap/schema/cosine.schema include /etc/openldap/schema/inetorgperson.schema include /etc/openldap/schema/nis.schema include /etc/openldap/schema/samba.schema .... sambaSamAccount posixAccount posixGroup ObjectClasses It is recommended that you maintain some indices on some of the most useful attributes, as in the following example, to speed up searches made on sambaSamAccount ObjectClasses (and possibly posixAccount and posixGroup as well): # Indices to maintain ## required by OpenLDAP index objectclass eq index cn pres,sub,eq index sn pres,sub,eq ## required to support pdb_getsampwnam index uid pres,sub,eq ## required to support pdb_getsambapwrid() index displayName pres,sub,eq ## uncomment these if you are storing posixAccount and ## posixGroup entries in the directory as well ##index uidNumber eq ##index gidNumber eq ##index memberUid eq index sambaSID eq index sambaPrimaryGroupSID eq index sambaDomainName eq index default sub Create the new index by executing: &rootprompt;./sbin/slapindex -f slapd.conf Remember to restart slapd after making these changes: &rootprompt;/etc/init.d/slapd restart LDAP database account containers LDIF file DNS Before you can add accounts to the LDAP database, you must create the account containers that they will be stored in. The following LDIF file should be modified to match your needs (DNS entries, and so on): # Organization for Samba Base dn: dc=quenya,dc=org objectclass: dcObject objectclass: organization dc: quenya o: Quenya Org Network description: The Samba-3 Network LDAP Example # Organizational Role for Directory Management dn: cn=Manager,dc=quenya,dc=org objectclass: organizationalRole cn: Manager description: Directory Manager # Setting up container for Users OU dn: ou=People,dc=quenya,dc=org objectclass: top objectclass: organizationalUnit ou: People # Setting up admin handle for People OU dn: cn=admin,ou=People,dc=quenya,dc=org cn: admin objectclass: top objectclass: organizationalRole objectclass: simpleSecurityObject userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz # Setting up container for groups dn: ou=Groups,dc=quenya,dc=org objectclass: top objectclass: organizationalUnit ou: Groups # Setting up admin handle for Groups OU dn: cn=admin,ou=Groups,dc=quenya,dc=org cn: admin objectclass: top objectclass: organizationalRole objectclass: simpleSecurityObject userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz # Setting up container for computers dn: ou=Computers,dc=quenya,dc=org objectclass: top objectclass: organizationalUnit ou: Computers # Setting up admin handle for Computers OU dn: cn=admin,ou=Computers,dc=quenya,dc=org cn: admin objectclass: top objectclass: organizationalRole objectclass: simpleSecurityObject userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz userPassword slappasswd The userPassword shown above should be generated using slappasswd. LDIF LDAP The following command will then load the contents of the LDIF file into the LDAP database. slapadd &prompt;slapadd -v -l initldap.dif Do not forget to secure your LDAP server with an adequate access control list as well as an admin password. secrets.tdb Before Samba can access the LDAP server, you need to store the LDAP admin password in the Samba-3 secrets.tdb database by: smbpasswd &rootprompt;smbpasswd -w secret LDAP smbd The following parameters are available in &smb.conf; only if your version of Samba was built with LDAP support. Samba automatically builds with LDAP support if the LDAP libraries are found. The best method to verify that Samba was built with LDAP support is: &rootprompt; smbd -b | grep LDAP HAVE_LDAP_H HAVE_LDAP HAVE_LDAP_DOMAIN2HOSTLIST HAVE_LDAP_INIT HAVE_LDAP_INITIALIZE HAVE_LDAP_SET_REBIND_PROC HAVE_LIBLDAP LDAP_SET_REBIND_PROC_ARGS If the build of the smbd command you are using does not produce output that includes HAVE_LDAP_H it is necessary to discover why the LDAP headers and libraries were not found during compilation. LDAP-related smb.conf options include these: ldapsam:url These are described in the &smb.conf; man page and so are not repeated here. However, an example for use with an LDAP directory is shown in the Configuration with LDAP. user yes MORIA NOLDOR LDAP related parameters: Define the DN used when binding to the LDAP servers. The password for this DN is not stored in smb.conf Set it using 'smbpasswd -w secret' to store the passphrase in the secrets.tdb file. If the "ldap admin dn" value changes, it must be reset. "cn=Manager,dc=quenya,dc=org" SSL directory connections can be configured by: ('off', 'start tls', or 'on' (default)) start tls syntax: passdb backend = ldapsam:ldap://server-name[:port] ldapsam:ldap://frodo.quenya.org smbpasswd -x delete the entire dn-entry no The machine and user suffix are added to the base suffix wrote WITHOUT quotes. NULL suffixes by default ou=People ou=Groups ou=Computers Trust UNIX account information in LDAP (see the smb.conf man page for details) Specify the base DN to use when searching the directory dc=quenya,dc=org User Management User AccountsAdding/Deleting Because user accounts are managed through the sambaSamAccount ObjectClass, you should modify your existing administration tools to deal with sambaSamAccount attributes. sambaSamAccount /etc/openldap/sldap.conf NSS Machine accounts are managed with the sambaSamAccount ObjectClass, just like user accounts. However, it is up to you to store those accounts in a different tree of your LDAP namespace. You should use ou=Groups,dc=quenya,dc=org to store groups and ou=People,dc=quenya,dc=org to store users. Just configure your NSS and PAM accordingly (usually, in the /etc/openldap/sldap.conf configuration file). POSIX posixGroup Domain Groups ADS In Samba-3, the group management system is based on POSIX groups. This means that Samba makes use of the posixGroup ObjectClass. For now, there is no NT-like group system management (global and local groups). Samba-3 knows only about Domain Groups and, unlike MS Windows 2000 and Active Directory, Samba-3 does not support nested groups. sambaSAMAccount There are two important points to remember when discussing the security of sambaSAMAccount entries in the directory. Never retrieve the SambaLMPassword or SambaNTPassword SambaNTPassword attribute values over an unencrypted LDAP session. Never allow non-admin users to view the SambaLMPassword or SambaNTPassword attribute values. clear-text impersonate LM/NT password hashes 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 Account Information Database section. encrypted session StartTLS LDAPS secure communications To remedy the first security issue, the &smb.conf; parameter defaults to require an encrypted session (on) using the default port of 636 when contacting the directory server. When using an OpenLDAP server, it is possible to use the StartTLS LDAP extended operation in the place of LDAPS. In either case, you are strongly encouraged to use secure communications protocols (so do not set off). LDAPS StartTLS LDAPv3 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. harvesting password hashes ACL slapd.conf 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=SambaLMPassword,SambaNTPassword by dn="cn=Samba Admin,ou=People,dc=quenya,dc=org" write by * none The sambaSamAccount ObjectClass is composed of the attributes shown in next tables: Part A, and Part B. sambaLMPasswordThe LanMan password 16-byte hash stored as a character representation of a hexadecimal string.sambaNTPasswordThe NT password 16-byte hash stored as a character representation of a hexadecimal string.sambaPwdLastSetThe integer time in seconds since 1970 when the sambaLMPassword and sambaNTPassword attributes were last set. sambaAcctFlagsString of 11 characters surrounded by square brackets [ ] representing account flags such as U (user), W (workstation), X (no password expiration), I (domain trust account), H (home dir required), S (server trust account), and D (disabled).sambaLogonTimeInteger value currently unused.sambaLogoffTimeInteger value currently unused.sambaKickoffTimeSpecifies the time (UNIX time format) when the user will be locked down and cannot login any longer. If this attribute is omitted, then the account will never expire. Using this attribute together with shadowExpire of the shadowAccount ObjectClass will enable accounts to expire completely on an exact date.sambaPwdCanChangeSpecifies the time (UNIX time format) after which the user is allowed to change his password. If attribute is not set, the user will be free to change his password whenever he wants.sambaPwdMustChangeSpecifies the time (UNIX time format) when the user is forced to change his password. If this value is set to 0, the user will have to change his password at first login. If this attribute is not set, then the password will never expire.sambaHomeDriveSpecifies the drive letter to which to map the UNC path specified by sambaHomePath. The drive letter must be specified in the form X: where X is the letter of the drive to map. Refer to the logon drive parameter in the smb.conf(5) man page for more information.sambaLogonScriptThe sambaLogonScript property specifies the path of the user's logon script, .CMD, .EXE, or .BAT file. The string can be null. The path is relative to the netlogon share. Refer to the parameter in the &smb.conf; man page for more information.sambaProfilePathSpecifies a path to the user's profile. This value can be a null string, a local absolute path, or a UNC path. Refer to the parameter in the &smb.conf; man page for more information.sambaHomePathThe sambaHomePath property specifies the path of the home directory for the user. The string can be null. If sambaHomeDrive is set and specifies a drive letter, sambaHomePath should be a UNC path. The path must be a network UNC path of the form \\server\share\directory. This value can be a null string. Refer to the logon home parameter in the &smb.conf; man page for more information. sambaUserWorkstationsHere you can give a comma-separated list of machines on which the user is allowed to login. You may observe problems when you try to connect to a Samba domain member. Because domain members are not in this list, the domain controllers will reject them. Where this attribute is omitted, the default implies no restrictions. sambaSIDThe security identifier(SID) of the user. The Windows equivalent of UNIX UIDs.sambaPrimaryGroupSIDThe security identifier (SID) of the primary group of the user.sambaDomainNameDomain the user is part of. PDC sambaSamAccount The majority of these parameters are only used when Samba is acting as a PDC of a domain (refer to Domain Control, for details on how to configure Samba as a PDC). The following four attributes are only stored with the sambaSamAccount entry if the values are non-default values: sambaHomePath sambaLogonScript sambaProfilePath sambaHomeDrive sambaHomePath sambaLogonScript sambaProfilePath sambaHomeDrive sambaSamAccount PDC smbHome These attributes are only stored with the sambaSamAccount entry if the values are non-default values. For example, assume MORIA has now been configured as a PDC and that \\%L\%u was defined in its &smb.conf; file. When a user named becky logs on to the domain, the string is expanded to \\MORIA\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 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 that demonstrates the use of the SambaSamAccount ObjectClass: dn: uid=guest2, ou=People,dc=quenya,dc=org sambaLMPassword: 878D8014606CDA29677A44EFA1353FC7 sambaPwdMustChange: 2147483647 sambaPrimaryGroupSID: S-1-5-21-2447931902-1787058256-3961074038-513 sambaNTPassword: 552902031BEDE9EFAAD3B435B51404EE sambaPwdLastSet: 1010179124 sambaLogonTime: 0 objectClass: sambaSamAccount uid: guest2 sambaKickoffTime: 2147483647 sambaAcctFlags: [UX ] sambaLogoffTime: 2147483647 sambaSID: S-1-5-21-2447931902-1787058256-3961074038-5006 sambaPwdCanChange: 0 The following is an LDIF entry for using both the sambaSamAccount and posixAccount ObjectClasses: dn: uid=gcarter, ou=People,dc=quenya,dc=org sambaLogonTime: 0 displayName: Gerald Carter sambaLMPassword: 552902031BEDE9EFAAD3B435B51404EE sambaPrimaryGroupSID: S-1-5-21-2447931902-1787058256-3961074038-1201 objectClass: posixAccount objectClass: sambaSamAccount sambaAcctFlags: [UX ] userPassword: {crypt}BpM2ej8Rkzogo uid: gcarter uidNumber: 9000 cn: Gerald Carter loginShell: /bin/bash logoffTime: 2147483647 gidNumber: 100 sambaKickoffTime: 2147483647 sambaPwdLastSet: 1010179230 sambaSID: S-1-5-21-2447931902-1787058256-3961074038-5004 homeDirectory: /home/moria/gcarter sambaPwdCanChange: 0 sambaPwdMustChange: 2147483647 sambaNTPassword: 878D8014606CDA29677A44EFA1353FC7 Samba-3 and later can update the non-Samba (LDAP) password stored with an account. When using pam_ldap, this allows changing both UNIX and Windows passwords at once. The options can have the values shown in Possible ldap passwd sync Values. ValueDescriptionyesWhen the user changes his password, update SambaNTPassword, SambaLMPassword, and the password fields.noOnly update SambaNTPassword and SambaLMPassword.onlyOnly update the LDAP password and let the LDAP server worry about the other fields. This option is only available on some LDAP servers and only when the LDAP server supports LDAP_EXOP_X_MODIFY_PASSWD. More information can be found in the &smb.conf; man page. SAM backendmysqlsam SQL backend Every so often someone comes along with what seems to them like a great new idea. Storing user accounts in a SQL backend is one of them. Those who want to do this are in the best position to know what the specific benefits are to them. This may sound like a cop-out, but in truth we cannot document every little detail of why certain things of marginal utility to the bulk of Samba users might make sense to the rest. In any case, the following instructions should help the determined SQL user to implement a working system. These account storage methods are not actively maintained by the Samba Team. MySQL You can set up your own table and specify the field names to pdb_mysql (see MySQL field names for MySQL passdb backend 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: &rootprompt;mysql -uusername -hhostname -ppassword \ databasename < /path/to/samba/examples/pdb/mysql/mysql.dump This plug-in lacks some good documentation, but here is some brief information. Add the following to the variable in your &smb.conf;: [other-plugins] mysql:identifier [other-plugins] The identifier can be any string you like, as long as it does not collide with the identifiers of other plugins or other instances of pdb_mysql. If you specify multiple pdb_mysql.so entries in , you also need to use different identifiers. Additional options can be given through the &smb.conf; file in the section. Refer to Basic smb.conf Options for MySQL passdb Backend. FieldContentsmysql hostHost name, defaults to `localhost'mysql passwordmysql userDefaults to `samba'mysql databaseDefaults to `samba'mysql portDefaults to 3306tableName of the table containing the users Since the password for the MySQL user is stored in the &smb.conf; file, you should make the &smb.conf; file readable only to the user who runs Samba. This is considered a security bug and will soon be fixed. Names of the columns are given in MySQL field names for MySQL passdb backend. The default column names can be found in the example table dump. FieldTypeContentslogon time columnint(9)UNIX timestamp of last logon of userlogoff time columnint(9)UNIX timestamp of last logoff of userkickoff time columnint(9)UNIX timestamp of moment user should be kicked off workstation (not enforced)pass last set time columnint(9)UNIX timestamp of moment password was last setpass can change time columnint(9)UNIX timestamp of moment from which password can be changedpass must change time columnint(9)UNIX timestamp of moment on which password must be changedusername columnvarchar(255)UNIX usernamedomain columnvarchar(255)NT domain user belongs tont username columnvarchar(255)NT usernamefullname columnvarchar(255)Full name of userhome dir columnvarchar(255)UNIX homedir path (equivalent of the parameter.dir drive columnvarchar(2)Directory drive path (e.g., H:)logon script columnvarchar(255)Batch file to run on client side when logging onprofile path columnvarchar(255)Path of profileacct desc columnvarchar(255)Some ASCII NT user dataworkstations columnvarchar(255)Workstations user can logon to (or NULL for all)unknown string columnvarchar(255)Unknown stringmunged dial columnvarchar(255)Unknownuser sid columnvarchar(255)NT user SIDgroup sid columnvarchar(255)NT group SIDlanman pass columnvarchar(255)Encrypted lanman passwordnt pass columnvarchar(255)Encrypted nt passwdplain pass columnvarchar(255)Plaintext passwordacct ctrl columnint(9)NT user dataunknown 3 columnint(9)Unknownlogon divs columnint(9)Unknownhours len columnint(9)Unknownbad password count columnint(5)Number of failed password tries before disabling an accountlogon count columnint(5)Number of logon attemptsunknown 6 columnint(9)Unknown 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, in which case the field data will not be updated. Setting a column name to NULL means the field should not be used. An example configuration is shown in Example Configuration for the MySQL passdb Backend. mysql:foo samba abmas samba domain name is static and can't be changed 'MYWORKGROUP': The fullname column comes from several other columns CONCAT(firstname,' ',surname): Samba should never write to the password columns lm_pass: nt_pass: The unknown 3 column is not stored NULL encrypted passwords I strongly discourage the use of plaintext passwords; however, you can use them. plaintext passwords 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 by making some "constant." For example, you can set `identifier:fullname column' to something like CONCAT(Firstname,' ',Surname) Or, set `identifier:workstations column' to: NULL. See the MySQL documentation for more language constructs. SAM backendxmlsam libxml2 pdb_xml This module requires libxml2 to be installed. The usage of pdb_xml is fairly straightforward. To export data, use: pdbedit $ pdbedit -e xml:filename where filename is the name of the file to put the data in. To import data, use: $ pdbedit -i xml:filename I've installed Samba, but now I can't log on with my UNIX account! Make sure your user has been added to the current Samba . Read the Account Management Tools, for details. A few complaints have been received from users who just moved to Samba-3. The following &smb.conf; file entries were causing problems: new accounts were being added to the old smbpasswd file, not to the tdbsam passdb.tdb file: ... smbpasswd, tdbsam ... Samba will add new accounts to the first entry in the passdb backend parameter entry. If you want to update to the tdbsam, then change the entry to: [globals] ... tdbsam, smbpasswd ... When explicitly setting an parameter, guest must be specified as the first entry on the line &smbmdash; for example, guest sam.