<title>Features and Benefits</title>
<para>
+<indexterm><primary>holy grail</primary></indexterm>
+<indexterm><primary>heterogeneous computing</primary></indexterm>
Integration of UNIX and Microsoft Windows NT through a unified logon has
been considered a <quote>holy grail</quote> in heterogeneous computing environments for
a long time.
</para>
<para>
+<indexterm><primary>interoperability</primary></indexterm>
+<indexterm><primary>domain user</primary></indexterm>
+<indexterm><primary>domain group</primary></indexterm>
+<indexterm><primary>group ownership</primary></indexterm>
There is one other facility without which UNIX and Microsoft Windows network
interoperability would suffer greatly. It is imperative that there be a
mechanism for sharing files across UNIX systems and to be able to assign
</para>
<para>
+<indexterm><primary>Pluggable Authentication Modules</primary><see>PAM</see></indexterm>
+<indexterm><primary>winbind</primary></indexterm>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>RPC</primary></indexterm>
<emphasis>winbind</emphasis> is a component of the Samba suite of programs that
solves the unified logon problem. Winbind uses a UNIX implementation of Microsoft
RPC calls, Pluggable Authentication Modules (PAMs), and the name service switch (NSS) to
<itemizedlist>
<listitem><para>
+<indexterm><primary>ADS</primary></indexterm>
+<indexterm><primary>NT4 domain</primary></indexterm>
Authentication of user credentials (via PAM). This makes it possible to
log onto a UNIX/Linux system using user and group accounts from a Windows
NT4 (including a Samba domain) or an Active Directory domain.
</para></listitem>
<listitem><para>
+<indexterm><primary>identity resolution</primary></indexterm>
+<indexterm><primary>NSS</primary></indexterm>
Identity resolution (via NSS). This is the default when winbind is not used.
</para></listitem>
<listitem><para>
+<indexterm><primary>UID</primary></indexterm>
+<indexterm><primary>GID</primary></indexterm>
+<indexterm><primary>SID</primary></indexterm>
+<indexterm><primary>idmap uid</primary></indexterm>
+<indexterm><primary>idmap gid</primary></indexterm>
+<indexterm><primary>idmap backend</primary></indexterm>
+<indexterm><primary></primary>LDAP</indexterm>
Winbind maintains a database called winbind_idmap.tdb in which it stores
mappings between UNIX UIDs, GIDs, and NT SIDs. This mapping is used only
for users and groups that do not have a local UID/GID. It stores the UID/GID
<note><para>
<indexterm><primary>winbindd</primary></indexterm>
<indexterm><primary>starting samba</primary><secondary>winbindd</secondary></indexterm>
+<indexterm><primary>/etc/passwd</primary></indexterm>
+<indexterm><primary>/etc/group</primary></indexterm>
+<indexterm><primary>smbd</primary></indexterm>
+<indexterm><primary>NSS</primary></indexterm>
If <command>winbindd</command> is not running, smbd (which calls <command>winbindd</command>) will fall back to
using purely local information from <filename>/etc/passwd</filename> and <filename>/etc/group</filename> and no dynamic
mapping will be used. On an operating system that has beeb enabled with the NSS,
made it difficult to integrate the two systems in a satisfactory
manner.</para>
- <para>One common solution in use today has been to create
+ <para>
+<indexterm><primary>synchronization problems</primary></indexterm>
+<indexterm><primary>passwords</primary></indexterm>
+ One common solution in use today has been to create
identically named user accounts on both the UNIX and Windows systems
and use the Samba suite of programs to provide file and print services
between the two. This solution is far from perfect, however, because
</itemizedlist>
- <para>Ideally, a prospective solution to the unified logon problem
+ <para>
+<indexterm><primary>unified logon</primary></indexterm>
+<indexterm><primary>duplication of information</primary></indexterm>
+ Ideally, a prospective solution to the unified logon problem
would satisfy all the above components without duplication of
information on the UNIX machines and without creating additional
tasks for the system administrator when maintaining users and
<sect1>
<title>What Winbind Provides</title>
- <para>Winbind unifies UNIX and Windows NT account management by
+ <para>
+<indexterm><primary>Windows account management</primary></indexterm>
+<indexterm><primary>UNIX users</primary></indexterm>
+<indexterm><primary>UNIX groups</primary></indexterm>
+<indexterm><primary>NT domain</primary></indexterm>
+ Winbind unifies UNIX and Windows NT account management by
allowing a UNIX box to become a full member of an NT domain. Once
this is done, the UNIX box will see NT users and groups as if
they were <quote>native</quote> UNIX users and groups, allowing the NT domain
to be used in much the same manner that NIS+ is used within
UNIX-only environments.</para>
- <para>The end result is that whenever a
+ <para>
+<indexterm><primary>Winbind hooks</primary></indexterm>
+<indexterm><primary>domain controller</primary></indexterm>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>redirection</primary></indexterm>
+ The end result is that whenever a
program on the UNIX machine asks the operating system to look up
a user or group name, the query will be resolved by asking the
NT domain controller for the specified domain to do the lookup.
redirection to the NT domain controller is completely
transparent.</para>
- <para>Users on the UNIX machine can then use NT user and group
+ <para>
+<indexterm><primary>user and group</primary></indexterm>
+<indexterm><primary>domain user</primary></indexterm>
+ Users on the UNIX machine can then use NT user and group
names as they would <quote>native</quote> UNIX names. They can chown files
so they are owned by NT domain users or even login to the
UNIX machine and run a UNIX X-Window session as a domain user.</para>
- <para>The only obvious indication that Winbind is being used is
+ <para>
+<indexterm><primary>domain controller</primary></indexterm>
+ The only obvious indication that Winbind is being used is
that user and group names take the form <constant>DOMAIN\user</constant> and
<constant>DOMAIN\group</constant>. This is necessary because it allows Winbind to determine
that redirection to a domain controller is wanted for a particular
lookup and which trusted domain is being referenced.</para>
- <para>Additionally, Winbind provides an authentication service
- that hooks into the PAM system
+ <para>
+<indexterm><primary>PAM-enabled</primary></indexterm>
+<indexterm><primary>domain controller</primary></indexterm>
+ Additionally, Winbind provides an authentication service that hooks into the PAM system
to provide authentication via an NT domain to any PAM-enabled
applications. This capability solves the problem of synchronizing
passwords between systems, since all passwords are stored in a single
<sect2>
<title>Target Uses</title>
- <para>Winbind is targeted at organizations that have an
+ <para>
+<indexterm><primary>infrastructure</primary></indexterm>
+ Winbind is targeted at organizations that have an
existing NT-based domain infrastructure into which they wish
to put UNIX workstations or servers. Winbind will allow these
organizations to deploy UNIX workstations without having to
simplifies the administrative overhead of deploying UNIX
workstations into an NT-based organization.</para>
- <para>Another interesting way in which we expect Winbind to
+ <para>
+<indexterm><primary>Appliances</primary></indexterm>
+<indexterm><primary>Winbind</primary></indexterm>
+ Another interesting way in which we expect Winbind to
be used is as a central part of UNIX-based appliances. Appliances
that provide file and print services to Microsoft-based networks
will be able to use Winbind to provide seamless integration of
<title>Handling of Foreign SIDs</title>
<para>
+<indexterm><primary>foreign SID</primary></indexterm>
The term <emphasis>foreign SID</emphasis> is often met with the reaction that it
is not relevant to a particular environment. The following documents an interchange
that took place on the Samba mailing list. It is a good example of the confusion
</para>
<para>
+<indexterm><primary>local domain</primary></indexterm>
Fact: Winbind is needed to handle users who use workstations that are NOT part
of the local domain.
</para>
<para>
+<indexterm><primary>PDC</primary></indexterm>
Response: <quote>Why? I've used Samba with workstations that are not part of my domains
lots of times without using winbind. I though winbind was for using Samba as a member server
in a domain controlled by another Samba/Windows PDC.</quote>
</para>
<para>
+<indexterm><primary>UID</primary></indexterm>
+<indexterm><primary>GID</primary></indexterm>
+<indexterm><primary>foreign user</primary></indexterm>
If the Samba server will be accessed from a domain other than the local Samba domain, or
if there will be access from machines that are not local domain members, winbind will
permit the allocation of UIDs and GIDs from the assigned pool that will keep the identity
</para>
<para>
+<indexterm><primary>PDC</primary></indexterm>
+<indexterm><primary>domain member</primary></indexterm>
+<indexterm><primary>domain non-member</primary></indexterm>
+<indexterm><primary>SID</primary></indexterm>
This means that winbind is eminently useful in cases where a single
- Samba PDC on a local network is combined with both domain member and non-domain member workstations.
+ Samba PDC on a local network is combined with both domain member and domain non-member workstations.
If winbind is not used, the user george on a Windows workstation that is not a domain
member will be able to access the files of a user called george in the account database
of the Samba server that is acting as a PDC. When winbind is used, the default condition
<sect1>
<title>How Winbind Works</title>
- <para>The Winbind system is designed around a client/server
+ <para>
+<indexterm><primary>winbindd</primary></indexterm>
+<indexterm><primary>UNIX domain socket</primary></indexterm>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>PAM</primary></indexterm>
+ The Winbind system is designed around a client/server
architecture. A long-running <command>winbindd</command> daemon
listens on a UNIX domain socket waiting for requests
to arrive. These requests are generated by the NSS and PAM
<sect2>
<title>Microsoft Remote Procedure Calls</title>
- <para>Over the last few years, efforts have been underway
+ <para>
+<indexterm><primary>Microsoft Remote Procedure Call</primary><see>MSRPC</see></indexterm>
+<indexterm><primary>PDC</primary></indexterm>
+<indexterm><primary>remote management</primary></indexterm>
+<indexterm><primary>user authentication</primary></indexterm>
+<indexterm><primary>print spooling</primary></indexterm>
+ Over the last few years, efforts have been underway
by various Samba Team members to decode various aspects of
the Microsoft Remote Procedure Call (MSRPC) system. This
system is used for most network-related operations between
functionality in Samba, it has also yielded a body of code that
can be used for other purposes.</para>
- <para>Winbind uses various MSRPC calls to enumerate domain users
+ <para>
+<indexterm><primary>MSRPC</primary></indexterm>
+<indexterm><primary>enumerate domain users</primary></indexterm>
+<indexterm><primary>enumerate domain groups</primary></indexterm>
+ Winbind uses various MSRPC calls to enumerate domain users
and groups and to obtain detailed information about individual
users or groups. Other MSRPC calls can be used to authenticate
NT domain users and to change user passwords. By directly querying
<title>Microsoft Active Directory Services</title>
<para>
- Since late 2001, Samba has gained the ability to
- interact with Microsoft Windows 2000 using its <quote>native
- mode</quote> protocols rather than the NT4 RPC services.
- Using LDAP and Kerberos, a domain member running
- Winbind can enumerate users and groups in exactly the
- same way as a Windows 200x client would, and in so doing
- provide a much more efficient and effective Winbind implementation.
- </para>
+<indexterm><primary>LDAP</primary></indexterm>
+<indexterm><primary>Kerberos</primary></indexterm>
+<indexterm><primary>Winbind</primary></indexterm>
+<indexterm><primary>native mode</primary></indexterm>
+ Since late 2001, Samba has gained the ability to interact with Microsoft Windows 2000 using its <quote>native
+ mode</quote> protocols rather than the NT4 RPC services. Using LDAP and Kerberos, a domain member running
+ Winbind can enumerate users and groups in exactly the same way as a Windows 200x client would, and in so doing
+ provide a much more efficient and effective Winbind implementation.
+ </para>
</sect2>
<sect2>
<title>Name Service Switch</title>
- <para>The NSS is a feature that is
- present in many UNIX operating systems. It allows system
+ <para>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>networked workstation</primary></indexterm>
+<indexterm><primary>NIS</primary></indexterm>
+<indexterm><primary>DNS</primary></indexterm>
+ The NSS is a feature that is present in many UNIX operating systems. It allows system
information such as hostnames, mail aliases, and user information
to be resolved from different sources. For example, a standalone
UNIX workstation may resolve system information from a series of
and then consult an NIS database for user information or a DNS server
for hostname information.</para>
- <para>The NSS application programming interface allows Winbind
+ <para>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>MSRPC</primary></indexterm>
+<indexterm><primary>trusted domain</primary></indexterm>
+<indexterm><primary>local users</primary></indexterm>
+<indexterm><primary>local groups</primary></indexterm>
+ The NSS application programming interface allows Winbind
to present itself as a source of system information when
resolving UNIX usernames and groups. Winbind uses this interface
and information obtained from a Windows NT server using MSRPC
an NT domain plus any trusted domain as though they were local
users and groups.</para>
- <para>The primary control file for NSS is
- <filename>/etc/nsswitch.conf</filename>.
+ <para>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
+<indexterm><primary>passwd</primary></indexterm>
+ The primary control file for NSS is <filename>/etc/nsswitch.conf</filename>.
When a UNIX application makes a request to do a lookup,
the C library looks in <filename>/etc/nsswitch.conf</filename>
for a line that matches the service type being requested; for
example, the <quote>passwd</quote> service type is used when user or group names
are looked up. This config line specifies which implementations
of that service should be tried and in what order. If the passwd
- config line is:</para>
-
- <para><screen>
- passwd: files example
- </screen></para>
-
- <para>then the C library will first load a module called
+ config line is:
+<screen>
+passwd: files example
+</screen>
+<indexterm><primary>/lib/libnss_files.so</primary></indexterm>
+<indexterm><primary>/lib/libnss_example.so</primary></indexterm>
+<indexterm><primary>resolver functions</primary></indexterm>
+ then the C library will first load a module called
<filename>/lib/libnss_files.so</filename> followed by
the module <filename>/lib/libnss_example.so</filename>. The
C library will dynamically load each of these modules in turn
the request. Once the request is resolved, the C library returns the
result to the application.</para>
- <para>This NSS interface provides an easy way for Winbind
+ <para>
+<indexterm><primary>NSS</primary></indexterm>
+<indexterm><primary>libnss_winbind.so</primary></indexterm>
+<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
+ This NSS interface provides an easy way for Winbind
to hook into the operating system. All that needs to be done
is to put <filename>libnss_winbind.so</filename> in <filename>/lib/</filename>
then add <quote>winbind</quote> into <filename>/etc/nsswitch.conf</filename> at
<sect2>
<title>Pluggable Authentication Modules</title>
- <para>PAMs provide
- a system for abstracting authentication and authorization
+ <para>
+<indexterm><primary>PAM</primary></indexterm>
+<indexterm><primary>authentication methods</primary></indexterm>
+<indexterm><primary>authorization</primary></indexterm>
+<indexterm><primary>NIS database</primary></indexterm>
+ PAMs provide a system for abstracting authentication and authorization
technologies. With a PAM module, it is possible to specify different
authentication methods for different system applications without
having to recompile these applications. PAM is also useful
stored in the local password file but only allow users resolved from
an NIS database to log in over the network.</para>
- <para>Winbind uses the authentication management and password
+ <para>
+<indexterm><primary>PAM</primary></indexterm>
+<indexterm><primary>Winbind</primary></indexterm>
+<indexterm><primary>authentication management</primary></indexterm>
+<indexterm><primary>password management</primary></indexterm>
+<indexterm><primary>PDC</primary></indexterm>
+ Winbind uses the authentication management and password
management PAM interface to integrate Windows NT users into a
UNIX system. This allows Windows NT users to log in to a UNIX
machine and be authenticated against a suitable PDC.
this change take effect directly on the PDC.
</para>
- <para>PAM is configured by providing control files in the directory
+ <para>
+<indexterm><primary>PAM</primary></indexterm>
+<indexterm><primary>/etc/pam.d/</primary></indexterm>
+<indexterm><primary>pam_winbind.so</primary></indexterm>
+<indexterm><primary>/lib/security/</primary></indexterm>
+ PAM is configured by providing control files in the directory
<filename>/etc/pam.d/</filename> for each of the services that
require authentication. When an authentication request is made
by an application, the PAM code in the C library looks up this
<sect2>
<title>User and Group ID Allocation</title>
- <para>When a user or group is created under Windows NT/200x,
+ <para>
+<indexterm><primary>RID</primary></indexterm>
+<indexterm><primary>Winbind</primary></indexterm>
+<indexterm><primary>UNIX ID</primary></indexterm>
+ When a user or group is created under Windows NT/200x,
it is allocated a numerical relative identifier (RID). This is
slightly different from UNIX, which has a range of numbers that are
used to identify users and the same range used to identify
time, Winbind will have mapped all Windows NT users and groups
to UNIX user IDs and group IDs.</para>
- <para>The results of this mapping are stored persistently in
+ <para>
+<indexterm><primary>ID mapping database</primary></indexterm>
+<indexterm><primary>tdb</primary></indexterm>
+<indexterm><primary>UNIX ID</primary></indexterm>
+<indexterm><primary>RID</primary></indexterm>
+ The results of this mapping are stored persistently in
an ID mapping database held in a tdb database. This ensures that
RIDs are mapped to UNIX IDs in a consistent way.</para>
</sect2>
<para>
<indexterm><primary>SAM</primary></indexterm>
- An active system can generate a lot of user and group
+<indexterm><primary>caching scheme</primary></indexterm>
+<indexterm><primary>Winbind</primary></indexterm>
+<indexterm><primary>ADS</primary></indexterm>
+<indexterm><primary>PDC</primary></indexterm>
+ An active directory system can generate a lot of user and group
name lookups. To reduce the network cost of these lookups, Winbind
uses a caching scheme based on the SAM sequence number supplied
by NT domain controllers. User or group information returned
<title>Introduction</title>
<para>
+<indexterm><primary>Winbind</primary></indexterm>
+<indexterm><primary>PDC</primary></indexterm>
+<indexterm><primary>authentication control</primary></indexterm>
This section describes the procedures used to get Winbind up and
running. Winbind is capable of providing access
and authentication control for Windows Domain users through an NT
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