Chapter 24. Winbind: Use of Domain Accounts
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## Chapter 24. Winbind: Use of Domain Accounts

### Tim Samba Team Potter

Samba Team

`<tpot@linuxcare.com.au>`

### Andrew Samba Team Tridgell

Samba Team

`<tridge@samba.org>`

### Naag Mummaneni

Notes for Solaris

`<getnag@rediffmail.com>`

### John SNAP Trostel

SNAP

`<jtrostel@snapserver.com>`

### Jelmer R. The Samba Team Vernooij

The Samba Team

`<jelmer@samba.org>`

### John H. Samba Team Terpstra

Samba Team

`<jht@samba.org>`

June 15, 2005

## Features and Benefits

Integration of UNIX and Microsoft Windows NT through a unified logon has been considered a “holy grail” in heterogeneous computing environments for a long time.

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 domain user and group ownerships with integrity.

winbind 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 allow Windows NT domain users to appear and operate as UNIX users on a UNIX machine. This chapter describes the Winbind system, the functionality it provides, how it is configured, and how it works internally.

Winbind provides three separate functions:

- 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.

- Identity resolution (via NSS). This is the default when winbind is not used.

- 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 allocated from the idmap uid/gid range that it has mapped to the NT SID. If `idmap backend` has been specified as `ldap:ldap://hostname[:389]`, then instead of using a local mapping, Winbind will obtain this information from the LDAP database.

### Note

If `winbindd` is not running, smbd (which calls `winbindd`) will fall back to using purely local information from `/etc/passwd` and `/etc/group` and no dynamic mapping will be used. On an operating system that has been enabled with the NSS, the resolution of user and group information will be accomplished via NSS.

Figure 24.1. Winbind Idmap

## Introduction

It is well known that UNIX and Microsoft Windows NT have different models for representing user and group information and use different technologies for implementing them. This fact has made it difficult to integrate the two systems in a satisfactory manner.

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 adding and deleting users on both sets of machines becomes a chore, and two sets of passwords are required both of which can lead to synchronization problems between the UNIX and Windows systems and confusion for users.

We divide the unified logon problem for UNIX machines into three smaller problems:

- Obtaining Windows NT user and group information.

- Authenticating Windows NT users.

- Password changing for Windows NT users.

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 groups on either system. The Winbind system provides a simple and elegant solution to all three components of the unified logon problem.

## What Winbind Provides

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 “native” UNIX users and groups, allowing the NT domain to be used in much the same manner that NIS+ is used within UNIX-only environments.

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. Because Winbind hooks into the operating system at a low level (via the NSS name resolution modules in the C library), this redirection to the NT domain controller is completely transparent.

Users on the UNIX machine can then use NT user and group names as they would “native” 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.

The only obvious indication that Winbind is being used is that user and group names take the form `DOMAIN\user` and `DOMAIN\group`. 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.

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 location (on the domain controller).

### Target Uses

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 maintain a separate account infrastructure. This greatly simplifies the administrative overhead of deploying UNIX workstations into an NT-based organization.

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 the appliance into the domain.

### Handling of Foreign SIDs

The term foreign SID 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 often expressed regarding the use of winbind.

Fact: Winbind is needed to handle users who use workstations that are NOT part of the local domain.

Response: “Why? I've used Samba with workstations that are not part of my domains lots of times without using winbind. I thought winbind was for using Samba as a member server in a domain controlled by another Samba/Windows PDC.”

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 of the foreign user separate from users that are members of the Samba domain.

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 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 is that the local user george will be treated as the account DOMAIN\george and the foreign (non-member of the domain) account will be treated as MACHINE\george because each has a different SID.

## How Winbind Works

The Winbind system is designed around a client/server architecture. A long-running `winbindd` daemon listens on a UNIX domain socket waiting for requests to arrive. These requests are generated by the NSS and PAM clients and are processed sequentially.

The technologies used to implement Winbind are described in detail below.

### Microsoft Remote Procedure Calls

Over the last few years, efforts have been underway by various Samba Team members to implement various aspects of the Microsoft Remote Procedure Call (MSRPC) system. This system is used for most network-related operations between Windows NT machines, including remote management, user authentication, and print spooling. Although initially this work was done to aid the implementation of Primary Domain Controller (PDC) functionality in Samba, it has also yielded a body of code that can be used for other purposes.

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 a Windows PDC for user and group information, Winbind maps the NT account information onto UNIX user and group names.

### Microsoft Active Directory Services

Since late 2001, Samba has gained the ability to interact with Microsoft Windows 2000 using its “native mode” 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.

### Name Service Switch

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 flat files stored on the local file system. A networked workstation may first attempt to resolve system information from local files, and then consult an NIS database for user information or a DNS server for hostname information.

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 calls to provide a new source of account enumeration. Using standard UNIX library calls, you can enumerate the users and groups on a UNIX machine running Winbind and see all users and groups in an NT domain plus any trusted domain as though they were local users and groups.

The primary control file for NSS is `/etc/nsswitch.conf`. When a UNIX application makes a request to do a lookup, the C library looks in `/etc/nsswitch.conf` for a line that matches the service type being requested; for example, the “passwd” 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:

    passwd: files example

then the C library will first load a module called `/lib/libnss_files.so` followed by the module `/lib/libnss_example.so`. The C library will dynamically load each of these modules in turn and call resolver functions within the modules to try to resolve the request. Once the request is resolved, the C library returns the result to the application.

This NSS interface provides an easy way for Winbind to hook into the operating system. All that needs to be done is to put `libnss_winbind.so` in `/lib/` then add “winbind” into `/etc/nsswitch.conf` at the appropriate place. The C library will then call Winbind to resolve user and group names.

### Pluggable Authentication Modules

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 for implementing a particular policy for authorization. For example, a system administrator may only allow console logins from users stored in the local password file but only allow users resolved from an NIS database to log in over the network.

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. These users can also change their passwords and have this change take effect directly on the PDC.

PAM is configured by providing control files in the directory `/etc/pam.d/` 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 control file to determine what modules to load to do the authentication check and in what order. This interface makes adding a new authentication service for Winbind very easy: simply copy the `pam_winbind.so` module to `/lib/security/`, and the PAM control files for relevant services are updated to allow authentication via Winbind. See the PAM documentation in PAM-Based Distributed Authentication, for more information.

### User and Group ID Allocation

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 groups. It is Winbind's job to convert RIDs to UNIX ID numbers and vice versa. When Winbind is configured, it is given part of the UNIX user ID space and a part of the UNIX group ID space in which to store Windows NT users and groups. If a Windows NT user is resolved for the first time, it is allocated the next UNIX ID from the range. The same process applies for Windows NT groups. Over time, Winbind will have mapped all Windows NT users and groups to UNIX user IDs and group IDs.

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.

### Result Caching

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 by a PDC is cached by Winbind along with a sequence number also returned by the PDC. This sequence number is incremented by Windows NT whenever any user or group information is modified. If a cached entry has expired, the sequence number is requested from the PDC and compared against the sequence number of the cached entry. If the sequence numbers do not match, then the cached information is discarded and up-to-date information is requested directly from the PDC.

## Installation and Configuration

### Introduction

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 or Windows 200x PDC for regular services, such as telnet and ftp, as well for Samba services.

- Why should I do this?

  This allows the Samba administrator to rely on the authentication mechanisms on the Windows NT/200x PDC for the authentication of domain members. Windows NT/200x users no longer need to have separate accounts on the Samba server.

- Who should be reading this document?

  This document is designed for system administrators. If you are implementing Samba on a file server and wish to (fairly easily) integrate existing Windows NT/200x users from your PDC onto the Samba server, this document is for you.

### Requirements

If you have a Samba configuration file that you are currently using, BACK IT UP! If your system already uses PAM, back up the `/etc/pam.d` directory contents! If you haven't already made a boot disk, MAKE ONE NOW!

Messing with the PAM configuration files can make it nearly impossible to log in to your machine. That's why you want to be able to boot back into your machine in single-user mode and restore your `/etc/pam.d` to the original state it was in if you get frustrated with the way things are going.

The latest version of Samba-3 includes a functioning winbindd daemon. Please refer to the main Samba Web page, or better yet, your closest Samba mirror site for instructions on downloading the source code.

To allow domain users the ability to access Samba shares and files, as well as potentially other services provided by your Samba machine, PAM must be set up properly on your machine. In order to compile the Winbind modules, you should have at least the PAM development libraries installed on your system. Please refer to the PAM Web site http://www.kernel.org/pub/linux/libs/pam/.

### Testing Things Out

Before starting, it is probably best to kill off all the Samba-related daemons running on your server. Kill off all smbd, nmbd, and winbindd processes that may be running. To use PAM, make sure that you have the standard PAM package that supplies the `/etc/pam.d` directory structure, including the PAM modules that are used by PAM-aware services, several PAM libraries, and the `/usr/doc` and `/usr/man` entries for PAM. Winbind is built better in Samba if the pam-devel package is also installed. This package includes the header files needed to compile PAM-aware applications.

#### Configure `nsswitch.conf` and the Winbind Libraries on Linux and Solaris

PAM is a standard component of most current generation UNIX/Linux systems. Unfortunately, few systems install the `pam-devel` libraries that are needed to build PAM-enabled Samba. Additionally, Samba-3 may auto-install the Winbind files into their correct locations on your system, so before you get too far down the track, be sure to check if the following configuration is really necessary. You may only need to configure `/etc/nsswitch.conf`.

The libraries needed to run the winbindd daemon through nsswitch need to be copied to their proper locations:

    root# cp ../samba/source/nsswitch/libnss_winbind.so /lib

I also found it necessary to make the following symbolic link:

`root#` `ln -s /lib/libnss_winbind.so /lib/libnss_winbind.so.2`

And, in the case of Sun Solaris:

    root# ln -s /usr/lib/libnss_winbind.so /usr/lib/libnss_winbind.so.1
    root# ln -s /usr/lib/libnss_winbind.so /usr/lib/nss_winbind.so.1
    root# ln -s /usr/lib/libnss_winbind.so /usr/lib/nss_winbind.so.2

As root, edit `/etc/nsswitch.conf` to allow user and group entries to be visible from the winbindd daemon. My `/etc/nsswitch.conf` file looked like this after editing:

    passwd:     files winbind
    shadow:     files
    group:      files winbind

The libraries needed by the `winbindd` daemon will be automatically entered into the `ldconfig` cache the next time your system reboots, but it is faster (and you do not need to reboot) if you do it manually:

    root# /sbin/ldconfig -v | grep winbind

This makes `libnss_winbind` available to winbindd and reports the current search path that is used by the dynamic link loader. The use of the `grep` filters the output of the `ldconfig` command so that we may see proof that this library is indeed recognized by the dynamic link loader.

The Sun Solaris dynamic link loader management tool is called `crle`. The use of this tool is necessary to instruct the dynamic link loader to search directories that contain library files that were not supplied as part of the original operating system platform. The following example shows how to use this tool to add the directory `/usr/local/lib` to the dynamic link loader's search path:

    root#  crle -u -l /usr/lib:/usr/local/lib

When executed without arguments, `crle` reports the current dynamic link loader configuration. This is demonstrated here:

    root#  crle

    Configuration file [version 4]: /var/ld/ld.config
      Default Library Path (ELF):   /lib:/usr/lib:/usr/local/lib
      Trusted Directories (ELF):    /lib/secure:/usr/lib/secure  (system default)

    Command line:
      crle -c /var/ld/ld.config -l /lib:/usr/lib:/usr/local/lib

From this it is apparent that the `/usr/local/lib` directory is included in the search dynamic link libraries in order to satisfy object module dependencies.

#### NSS Winbind on AIX

(This section is only for those running AIX.)

The Winbind AIX identification module gets built as `libnss_winbind.so` in the nsswitch directory of the Samba source. This file can be copied to `/usr/lib/security`, and the AIX naming convention would indicate that it should be named WINBIND. A stanza like the following:

    WINBIND:
            program = /usr/lib/security/WINBIND
            options = authonly

can then be added to `/usr/lib/security/methods.cfg`. This module only supports identification, but there have been reports of success using the standard Winbind PAM module for authentication. Use caution configuring loadable authentication modules, since misconfiguration can make it impossible to log on to the system. Information regarding the AIX authentication module API can be found in the “Kernel Extensions and Device Support Programming Concepts for AIX” document that describes the Loadable Authentication Module Programming Interface for AIX. Further information on administering the modules can be found in the System Management Guide: Operating System and Devices.

#### Configure smb.conf

Several parameters are needed in the `smb.conf` file to control the behavior of winbindd. These are described in more detail in the winbindd(8) man page. My `smb.conf` file, as shown in the smb.conf for Winbind Setup, was modified to include the necessary entries in the [global] section.

Example 24.1. smb.conf for Winbind Setup

`[global]`
# separate domain and username with '\', like DOMAIN\username
`winbind separator = \`
# use uids from 10000 to 20000 for domain users
`idmap uid = 10000-20000`
# use gids from 10000 to 20000 for domain groups
`idmap gid = 10000-20000`
# allow enumeration of winbind users and groups
`winbind enum users = yes`
`winbind enum groups = yes`
# give winbind users a real shell (only needed if they have telnet access)
`template homedir = /home/winnt/%D/%U`
`template shell = /bin/bash`

#### Join the Samba Server to the PDC Domain

All machines that will participate in domain security should be members of the domain. This applies also to the PDC and all BDCs.

The process of joining a domain requires the use of the `net rpc join` command. This process communicates with the domain controller it will register with (usually the PDC) via MS DCE RPC. This means, of course, that the `smbd` process must be running on the target domain controller. It is therefore necessary to temporarily start Samba on a PDC so that it can join its own domain.

Enter the following command to make the Samba server join the domain, where `PDC` is the name of your PDC and `Administrator` is a domain user who has administrative privileges in the domain.

### Note

Before attempting to join a machine to the domain, verify that Samba is running on the target domain controller (usually PDC) and that it is capable of being reached via ports 137/udp, 135/tcp, 139/tcp, and 445/tcp (if Samba or Windows Server 2Kx).

The use of the `net rpc join` facility is shown here:

    root# /usr/local/samba/bin/net rpc join -S PDC -U Administrator

The proper response to the command should be “Joined the domain `DOMAIN`” where `DOMAIN` is your domain name.

#### Starting and Testing the `winbindd` Daemon

Eventually, you will want to modify your Samba startup script to automatically invoke the winbindd daemon when the other parts of Samba start, but it is possible to test out just the Winbind portion first. To start up Winbind services, enter the following command as root:

    root# /usr/local/samba/sbin/winbindd

Use the appropriate path to the location of the `winbindd` executable file.

### Note

The command to start up Winbind services assumes that Samba has been installed in the `/usr/local/samba` directory tree. You may need to search for the location of Samba files if this is not the location of `winbindd` on your system.

I'm always paranoid and like to make sure the daemon is really running.

    root# ps -ae | grep winbindd

This command should produce output like the following if the daemon is running.

    3025 ?        00:00:00 winbindd

Now, for the real test, try to get some information about the users on your PDC:

    root# /usr/local/samba/bin/wbinfo -u

This should echo back a list of users on your Windows users on your PDC. For example, I get the following response:

    CEO\Administrator
    CEO\burdell
    CEO\Guest
    CEO\jt-ad
    CEO\krbtgt
    CEO\TsInternetUser

Obviously, I have named my domain “CEO” and my winbind separator is “\”.

You can do the same sort of thing to get group information from the PDC:

    root# /usr/local/samba/bin/wbinfo -g
    CEO\Domain Admins
    CEO\Domain Users
    CEO\Domain Guests
    CEO\Domain Computers
    CEO\Domain Controllers
    CEO\Cert Publishers
    CEO\Schema Admins
    CEO\Enterprise Admins
    CEO\Group Policy Creator Owners

The function `getent` can now be used to get unified lists of both local and PDC users and groups. Try the following command:

    root# getent passwd

You should get a list that looks like your `/etc/passwd` list followed by the domain users with their new UIDs, GIDs, home directories, and default shells.

The same thing can be done for groups with the command:

    root# getent group

#### Fix the init.d Startup Scripts

##### Linux

The winbindd daemon needs to start up after the smbd and nmbd daemons are running. To accomplish this task, you need to modify the startup scripts of your system. They are located at `/etc/init.d/smb` in Red Hat Linux and in `/etc/init.d/samba` in Debian Linux. Edit your script to add commands to invoke this daemon in the proper sequence. My startup script starts up smbd, nmbd, and winbindd from the `/usr/local/samba/bin` directory directly. The `start` function in the script looks like this:

    start() {
            KIND="SMB"
            echo -n $"Starting $KIND services: "
            daemon /usr/local/samba/bin/smbd $SMBDOPTIONS
            RETVAL=$?
            echo
            KIND="NMB"
            echo -n $"Starting $KIND services: "
            daemon /usr/local/samba/bin/nmbd $NMBDOPTIONS
            RETVAL2=$?
            echo
            KIND="Winbind"
            echo -n $"Starting $KIND services: "
            daemon /usr/local/samba/sbin/winbindd
            RETVAL3=$?
            echo
            [ $RETVAL -eq 0 -a $RETVAL2 -eq 0 -a $RETVAL3 -eq 0 ] && \
    		touch /var/lock/subsys/smb || RETVAL=1
            return $RETVAL
    }

If you would like to run winbindd in dual daemon mode, replace the line:

            daemon /usr/local/samba/sbin/winbindd

in the example above with:

            daemon /usr/local/samba/sbin/winbindd -D

.

The `stop` function has a corresponding entry to shut down the services and looks like this:

    stop() {
            KIND="SMB"
            echo -n $"Shutting down $KIND services: "
            killproc smbd
            RETVAL=$?
            echo
            KIND="NMB"
            echo -n $"Shutting down $KIND services: "
            killproc nmbd
            RETVAL2=$?
            echo
            KIND="Winbind"
            echo -n $"Shutting down $KIND services: "
            killproc winbindd
            RETVAL3=$?
            [ $RETVAL -eq 0 -a $RETVAL2 -eq 0 -a $RETVAL3 -eq 0 ] && \
    		 rm -f /var/lock/subsys/smb
            echo ""
            return $RETVAL
    }

##### Solaris

Winbind does not work on Solaris 9; see Winbind on Solaris 9 section for details.

On Solaris, you need to modify the `/etc/init.d/samba.server` startup script. It usually only starts smbd and nmbd but should now start winbindd, too. If you have Samba installed in `/usr/local/samba/bin`, the file could contains something like this:

    	##
    	## samba.server
    	##

    	if [ ! -d /usr/bin ]
    	then                    # /usr not mounted
    		exit
    	fi

    	killproc() {            # kill the named process(es)
    		pid=`/usr/bin/ps -e |
    		     /usr/bin/grep -w $1 |
    		     /usr/bin/sed -e 's/^  *//' -e 's/ .*//'`
    		[ "$pid" != "" ] && kill $pid
    	}

    	# Start/stop processes required for Samba server

    	case "$1" in

    	'start')
    	#
    	# Edit these lines to suit your installation (paths, workgroup, host)
    	#
    	echo Starting SMBD
    	   /usr/local/samba/bin/smbd -D -s \
    		/usr/local/samba/smb.conf

    	echo Starting NMBD
    	   /usr/local/samba/bin/nmbd -D -l \
    		/usr/local/samba/var/log -s /usr/local/samba/smb.conf

    	echo Starting Winbind Daemon
    	   /usr/local/samba/sbin/winbindd
    	   ;;

    	'stop')
    	   killproc nmbd
    	   killproc smbd
    	   killproc winbindd
    	   ;;

    	*)
    	   echo "Usage: /etc/init.d/samba.server { start | stop }"
    	   ;;
    	esac

Again, if you would like to run Samba in dual daemon mode, replace:

    /usr/local/samba/sbin/winbindd

in the script above with:

    /usr/local/samba/sbin/winbindd -D

##### Restarting

If you restart the smbd, nmbd, and winbindd daemons at this point, you should be able to connect to the Samba server as a domain member just as if you were a local user.

#### Configure Winbind and PAM

If you have made it this far, you know that `winbindd` and Samba are working together. If you want to use Winbind to provide authentication for other services, keep reading. The PAM configuration files need to be altered in this step. (Did you remember to make backups of your original `/etc/pam.d` files? If not, do it now.)

You will need a PAM module to use winbindd with these other services. This module will be compiled in the `../source/nsswitch` directory by invoking the command:

    root# make nsswitch/pam_winbind.so

from the `../source` directory. The `pam_winbind.so` file should be copied to the location of your other PAM security modules. On my Red Hat system, this was the `/lib/security` directory. On Solaris, the PAM security modules reside in `/usr/lib/security`.

    root# cp ../samba/source/nsswitch/pam_winbind.so /lib/security

##### Linux/FreeBSD-Specific PAM Configuration

The `/etc/pam.d/samba` file does not need to be changed. I just left this file as it was:

    auth    required  /lib/security/pam_stack.so service=system-auth
    account required  /lib/security/pam_stack.so service=system-auth

The other services that I modified to allow the use of Winbind as an authentication service were the normal login on the console (or a terminal session), telnet logins, and ftp service. In order to enable these services, you may first need to change the entries in `/etc/xinetd.d` (or `/etc/inetd.conf`). Red Hat Linux 7.1 and later uses the new xinetd.d structure, in this case you need to change the lines in `/etc/xinetd.d/telnet` and `/etc/xinetd.d/wu-ftp` from:

    	enable = no

to

    	enable = yes

For ftp services to work properly, you will also need to either have individual directories for the domain users already present on the server or change the home directory template to a general directory for all domain users. These can be easily set using the `smb.conf` global entry template homedir.

### Note

The directory in template homedir is not created automatically! Use pam_mkhomedir or pre-create the directories of users to make sure users can log in on UNIX with their own home directory.

The `/etc/pam.d/ftp` file can be changed to allow Winbind ftp access in a manner similar to the samba file. My `/etc/pam.d/ftp` file was changed to look like this:

    auth       required     /lib/security/pam_listfile.so item=user sense=deny \
    	 file=/etc/ftpusers onerr=succeed
    auth       sufficient   /lib/security/pam_winbind.so
    auth       required     /lib/security/pam_stack.so service=system-auth
    auth       required     /lib/security/pam_shells.so
    account    sufficient   /lib/security/pam_winbind.so
    account    required     /lib/security/pam_stack.so service=system-auth
    session    required     /lib/security/pam_stack.so service=system-auth

The `/etc/pam.d/login` file can be changed in nearly the same way. It now looks like this:

    auth       required     /lib/security/pam_securetty.so
    auth       sufficient   /lib/security/pam_winbind.so
    auth       sufficient   /lib/security/pam_unix.so use_first_pass
    auth       required     /lib/security/pam_stack.so service=system-auth
    auth       required     /lib/security/pam_nologin.so
    account    sufficient   /lib/security/pam_winbind.so
    account    required     /lib/security/pam_stack.so service=system-auth
    password   required     /lib/security/pam_stack.so service=system-auth
    session    required     /lib/security/pam_stack.so service=system-auth
    session    optional     /lib/security/pam_console.so

In this case, I added the

    auth sufficient /lib/security/pam_winbind.so

lines as before, but also added the

    required pam_securetty.so

above it to disallow root logins over the network. I also added a

    sufficient /lib/security/pam_unix.so
    use_first_pass

line after the `winbind.so` line to get rid of annoying double prompts for passwords.

##### Solaris-Specific Configuration

The `/etc/pam.conf` needs to be changed. I changed this file so my Domain users can log on both locally as well as with telnet. The following are the changes that I made. You can customize the `pam.conf` file as per your requirements, but be sure of those changes because in the worst case it will leave your system nearly impossible to boot.

    #
    #ident "@(#)pam.conf 1.14 99/09/16 SMI"
    #
    # Copyright (c) 1996-1999, Sun Microsystems, Inc.
    # All Rights Reserved.
    #
    # PAM configuration
    #
    # Authentication management
    #
    login   auth required   /usr/lib/security/pam_winbind.so
    login auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
    login auth required  /usr/lib/security/$ISA/pam_dial_auth.so.1 try_first_pass
    #
    rlogin  auth sufficient /usr/lib/security/pam_winbind.so
    rlogin  auth sufficient /usr/lib/security/$ISA/pam_rhosts_auth.so.1
    rlogin auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
    #
    dtlogin auth sufficient /usr/lib/security/pam_winbind.so
    dtlogin auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
    #
    rsh auth required /usr/lib/security/$ISA/pam_rhosts_auth.so.1
    other   auth sufficient /usr/lib/security/pam_winbind.so
    other auth required /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
    #
    # Account management
    #
    login   account sufficient      /usr/lib/security/pam_winbind.so
    login account requisite /usr/lib/security/$ISA/pam_roles.so.1
    login account required /usr/lib/security/$ISA/pam_unix.so.1
    #
    dtlogin account sufficient      /usr/lib/security/pam_winbind.so
    dtlogin account requisite /usr/lib/security/$ISA/pam_roles.so.1
    dtlogin account required /usr/lib/security/$ISA/pam_unix.so.1
    #
    other   account sufficient      /usr/lib/security/pam_winbind.so
    other account requisite /usr/lib/security/$ISA/pam_roles.so.1
    other account required /usr/lib/security/$ISA/pam_unix.so.1
    #
    # Session management
    #
    other session required /usr/lib/security/$ISA/pam_unix.so.1
    #
    # Password management
    #
    #other   password sufficient     /usr/lib/security/pam_winbind.so
    other password required /usr/lib/security/$ISA/pam_unix.so.1
    dtsession auth required /usr/lib/security/$ISA/pam_unix.so.1
    #
    # Support for Kerberos V5 authentication (uncomment to use Kerberos)
    #
    #rlogin auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
    #login auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
    #dtlogin auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
    #other auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
    #dtlogin account optional /usr/lib/security/$ISA/pam_krb5.so.1
    #other account optional /usr/lib/security/$ISA/pam_krb5.so.1
    #other session optional /usr/lib/security/$ISA/pam_krb5.so.1
    #other password optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass

I also added a `try_first_pass` line after the `winbind.so` line to get rid of annoying double prompts for passwords.

Now restart your Samba and try connecting through your application that you configured in the pam.conf.

## Conclusion

The Winbind system, through the use of the NSS, PAMs, and appropriate Microsoft RPC calls, have allowed us to provide seamless integration of Microsoft Windows NT domain users on a UNIX system. The result is a great reduction in the administrative cost of running a mixed UNIX and NT network.

## Common Errors

Winbind has a number of limitations in its current released version that we hope to overcome in future releases:

- Winbind is currently only available for the Linux, Solaris, AIX, and IRIX operating systems, although ports to other operating systems are certainly possible. For such ports to be feasible, we require the C library of the target operating system to support the NSS and PAM systems. This is becoming more common as NSS and PAM gain support among UNIX vendors.

- The mappings of Windows NT RIDs to UNIX IDs is not made algorithmically and depends on the order in which unmapped users or groups are seen by Winbind. It may be difficult to recover the mappings of RID to UNIX ID if the file containing this information is corrupted or destroyed.

- Currently the Winbind PAM module does not take into account possible workstation and logon time restrictions that may be set for Windows NT users; this is instead up to the PDC to enforce.

### NSCD Problem Warning

### Warning

Do not under any circumstances run `nscd` on any system on which `winbindd` is running.

If `nscd` is running on the UNIX/Linux system, then even though NSSWITCH is correctly configured, it will not be possible to resolve domain users and groups for file and directory controls.

### Winbind Is Not Resolving Users and Groups

“ My `smb.conf` file is correctly configured. I have specified idmap uid = 12000, and idmap gid = 3000-3500 and `winbind` is running. When I do the following, it all works fine. ”

    root# wbinfo -u
    MIDEARTH\maryo
    MIDEARTH\jackb
    MIDEARTH\ameds
    ...
    MIDEARTH\root

    root# wbinfo -g
    MIDEARTH\Domain Users
    MIDEARTH\Domain Admins
    MIDEARTH\Domain Guests
    ...
    MIDEARTH\Accounts

    root# getent passwd
    root:x:0:0:root:/root:/bin/bash
    bin:x:1:1:bin:/bin:/bin/bash
    ...
    maryo:x:15000:15003:Mary Orville:/home/MIDEARTH/maryo:/bin/false

“ But the following command just fails: ”

    root# chown maryo a_file
    chown: `maryo': invalid user

“ This is driving me nuts! What can be wrong? ”

Same problem as the one above. Your system is likely running `nscd`, the name service caching daemon. Shut it down, do not restart it! You will find your problem resolved. Alternately, fix the operation of nscd to resolve the problem.

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