<< Back to man.ChinaUnix.net

Chapter 23. Winbind: Use of Domain Accounts

Tim Potter

Andrew Tridgell

Samba Team

Naag Mummaneni

Notes for Solaris

John Trostel

Jelmer R. Vernooij

The Samba Team

John H. Terpstra

Samba Team

27 June 2002

Table of Contents

Features and Benefits
Introduction
What Winbind Provides
Target Uses
Handling of Foreign SIDs
How Winbind Works
Microsoft Remote Procedure Calls
Microsoft Active Directory Services
Name Service Switch
Pluggable Authentication Modules
User and Group ID Allocation
Result Caching
Installation and Configuration
Introduction
Requirements
Testing Things Out
Conclusion
Common Errors
NSCD Problem Warning
Winbind Is Not Resolving Users and Groups

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, and the Name Service Switch to allow Windows NT domain users to appear and operate as UNIX users on a UNIX machine. This chapter describes the Winbind system, explaining 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 stored 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 beeb enabled with the name service switcher (NSS) the resoltion of user and group information will be accomplished via NSS.

Figure 23.1. Winbind Idmap

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, as 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 lookup 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 as 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 Pluggable Authentication Modules (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 though winbind was for using samba as a memberserver 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.

Which means that that winbind is eminently useful in cases where one just has a single Samba PDC on a local network combined of both domain member and non-domain member workstations. If winbind is not used, the user george on an 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 is 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 decode 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 Name Service Switch, or 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 filesystem. 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, one can enumerate the users and groups on a UNIX machine running Winbind and see all users and groups in a 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

Pluggable Authentication Modules, also known as PAM, is 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 a 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 Primary Domain Controller. These users can also change their passwords and have this change take effect directly on the Primary Domain Controller.

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. All that needs to be done is that the pam_winbind.so module is copied 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 in which 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 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 back to the original state they were 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 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 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: ZZ

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

Now, as root you need to edit /etc/nsswitch.conf to allow user and group entries to be visible from the winbindd daemon. My /etc/nsswitch.conf file look 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 echos back a check to you.

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 success reports using the standard Winbind PAM module for authentication. Use caution configuring loadable authentication modules since you can make it impossible to logon to the system. More information about the AIX authentication module API can be found at “Kernel Extensions and Device Support Programming Concepts for AIX in Chapter 18(John, there is no section like this in 18). Loadable Authentication Module Programming Interface and more information on administering the modules can be found at 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 next example, was modified to include the necessary entries in the [global] section.

Example 23.1. smb.conf for Winbind set-up

[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 DC. This means that it is 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 DC (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.

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

Note

The above 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.

Winbindd can now also run in “dual daemon mode”. This will make it run as two processes. The first will answer all requests from the cache, thus making responses to clients faster. The other will update the cache for the query that the first has just responded. The advantage of this is that responses stay accurate and are faster. You can enable dual daemon mode by adding -B to the command-line:

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

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 this, if the daemon is running you would expect to see a report something like this:

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 they are located 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 -B

.

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 -B

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 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 logon both locally as well as 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 Name Service Switch, Pluggable Authentication Modules, 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 Name Service Switch and Pluggable Authentication Modules 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 mapping 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.