winbindd

## Name

winbindd — Name Service Switch daemon for resolving names from NT servers

## Synopsis

`winbindd` [-F] [-S] [-i] [-Y] [-d <debug level>] [-s <smb config file>] [-n]

## DESCRIPTION

This program is part of the Samba(7) suite.

winbindd is a daemon that provides a service for the Name Service Switch capability that is present in most modern C libraries. The Name Service Switch allows user and system information to be obtained from different databases services such as NIS or DNS. The exact behaviour can be configured throught the `/etc/nsswitch.conf` file. Users and groups are allocated as they are resolved to a range of user and group ids specified by the administrator of the Samba system.

The service provided by winbindd is called `winbind' and can be used to resolve user and group information from a Windows NT server. The service can also provide authentication services via an associated PAM module.

The `pam_winbind` module in the 2.2.2 release only supports the `auth` and `account` module-types. The latter simply performs a getpwnam() to verify that the system can obtain a uid for the user. If the `libnss_winbind` library has been correctly installed, this should always succeed.

The following nsswitch databases are implemented by the winbindd service:

hosts

  User information traditionally stored in the `hosts(5)` file and used by gethostbyname(3) functions. Names are resolved through the WINS server or by broadcast.

passwd

  User information traditionally stored in the `passwd(5)` file and used by getpwent(3) functions.

group

  Group information traditionally stored in the `group(5)` file and used by getgrent(3) functions.

For example, the following simple configuration in the `/etc/nsswitch.conf` file can be used to initially resolve user and group information from `/etc/passwd` and `/etc/group` and then from the Windows NT server.

    passwd:         files winbind
    group:          files winbind

The following simple configuration in the `/etc/nsswitch.conf` file can be used to initially resolve hostnames from `/etc/hosts` and then from the WINS server.

## OPTIONS

-F

  If specified, this parameter causes the main winbindd process to not daemonize, i.e. double-fork and disassociate with the terminal. Child processes are still created as normal to service each connection request, but the main process does not exit. This operation mode is suitable for running winbindd under process supervisors such as supervise and svscan from Daniel J. Bernstein's daemontools package, or the AIX process monitor.

-S

  If specified, this parameter causes winbindd to log to standard output rather than a file.

-V

  Prints the version number for smbd.

-s <configuration file>

  The file specified contains the configuration details required by the server. The information in this file includes server-specific information such as what printcap file to use, as well as descriptions of all the services that the server is to provide. See `smb.conf` for more information. The default configuration file name is determined at compile time.

-d|--debug=debuglevel

  `debuglevel` is an integer from 0 to 10. The default value if this parameter is not specified is zero.

  The higher this value, the more detail will be logged to the log files about the activities of the server. At level 0, only critical errors and serious warnings will be logged. Level 1 is a reasonable level for day to day running - it generates a small amount of information about operations carried out.

  Levels above 1 will generate considerable amounts of log data, and should only be used when investigating a problem. Levels above 3 are designed for use only by developers and generate HUGE amounts of log data, most of which is extremely cryptic.

  Note that specifying this parameter here will override the `log level` parameter in the `smb.conf` file.

-l|--logfile=logbasename

  File name for log/debug files. The extension `".client"` will be appended. The log file is never removed by the client.

-h|--help

  Print a summary of command line options.

-i

  Tells winbindd to not become a daemon and detach from the current terminal. This option is used by developers when interactive debugging of winbindd is required. winbindd also logs to standard output, as if the -S parameter had been given.

-n

  Disable caching. This means winbindd will always have to wait for a response from the domain controller before it can respond to a client and this thus makes things slower. The results will however be more accurate, since results from the cache might not be up-to-date. This might also temporarily hang winbindd if the DC doesn't respond.

-Y

  Single daemon mode. This means winbindd will run as a single process (the mode of operation in Samba 2.2). Winbindd's default behavior is to launch a child process that is responsible for updating expired cache entries.

## NAME AND ID RESOLUTION

Users and groups on a Windows NT server are assigned a relative id (rid) which is unique for the domain when the user or group is created. To convert the Windows NT user or group into a unix user or group, a mapping between rids and unix user and group ids is required. This is one of the jobs that winbindd performs.

As winbindd users and groups are resolved from a server, user and group ids are allocated from a specified range. This is done on a first come, first served basis, although all existing users and groups will be mapped as soon as a client performs a user or group enumeration command. The allocated unix ids are stored in a database file under the Samba lock directory and will be remembered.

WARNING: The rid to unix id database is the only location where the user and group mappings are stored by winbindd. If this file is deleted or corrupted, there is no way for winbindd to determine which user and group ids correspond to Windows NT user and group rids.

## CONFIGURATION

Configuration of the winbindd daemon is done through configuration parameters in the smb.conf(5) file. All parameters should be specified in the [global] section of smb.conf.

- `winbind separator`

- `idmap uid`

- `idmap gid`

- `winbind cache time`

- `winbind enum users`

- `winbind enum groups`

- `template homedir`

- `template shell`

- `winbind use default domain`

## EXAMPLE SETUP

To setup winbindd for user and group lookups plus authentication from a domain controller use something like the following setup. This was tested on a RedHat 6.2 Linux box.

In `/etc/nsswitch.conf` put the following:

    passwd:     files winbind
    group:      files winbind

In `/etc/pam.d/*` replace the `auth` lines with something like this:

    auth       required	/lib/security/pam_securetty.so
    auth       required	/lib/security/pam_nologin.so
    auth       sufficient	/lib/security/pam_winbind.so
    auth       required     /lib/security/pam_pwdb.so use_first_pass shadow nullok

Note in particular the use of the `sufficient` keyword and the `use_first_pass` keyword.

Now replace the account lines with this:

account required /lib/security/pam_winbind.so

The next step is to join the domain. To do that use the net program like this:

net join -S PDC -U Administrator

The username after the `-U` can be any Domain user that has administrator privileges on the machine. Substitute the name or IP of your PDC for "PDC".

Next copy `libnss_winbind.so` to `/lib` and `pam_winbind.so` to `/lib/security`. A symbolic link needs to be made from `/lib/libnss_winbind.so` to `/lib/libnss_winbind.so.2`. If you are using an older version of glibc then the target of the link should be `/lib/libnss_winbind.so.1`.

Finally, setup a smb.conf(5) containing directives like the following:

    [global]
    	winbind separator = +
            winbind cache time = 10
            template shell = /bin/bash
            template homedir = /home/%D/%U
            idmap uid = 10000-20000
            idmap gid = 10000-20000
            workgroup = DOMAIN
            security = domain
            password server = *

Now start winbindd and you should find that your user and group database is expanded to include your NT users and groups, and that you can login to your unix box as a domain user, using the DOMAIN+user syntax for the username. You may wish to use the commands getent passwd and getent group to confirm the correct operation of winbindd.

## NOTES

The following notes are useful when configuring and running winbindd:

nmbd(8) must be running on the local machine for winbindd to work. winbindd queries the list of trusted domains for the Windows NT server on startup and when a SIGHUP is received. Thus, for a running winbindd to become aware of new trust relationships between servers, it must be sent a SIGHUP signal.

PAM is really easy to misconfigure. Make sure you know what you are doing when modifying PAM configuration files. It is possible to set up PAM such that you can no longer log into your system.

If more than one UNIX machine is running winbindd, then in general the user and groups ids allocated by winbindd will not be the same. The user and group ids will only be valid for the local machine.

If the the Windows NT RID to UNIX user and group id mapping file is damaged or destroyed then the mappings will be lost.

## SIGNALS

The following signals can be used to manipulate the winbindd daemon.

SIGHUP

  Reload the smb.conf(5) file and apply any parameter changes to the running version of winbindd. This signal also clears any cached user and group information. The list of other domains trusted by winbindd is also reloaded.

SIGUSR2

  The SIGUSR2 signal will cause winbindd to write status information to the winbind log file including information about the number of user and group ids allocated by winbindd.

  Log files are stored in the filename specified by the log file parameter.

## FILES

`/etc/nsswitch.conf(5)`

  Name service switch configuration file.

/tmp/.winbindd/pipe

  The UNIX pipe over which clients communicate with the winbindd program. For security reasons, the winbind client will only attempt to connect to the winbindd daemon if both the `/tmp/.winbindd` directory and `/tmp/.winbindd/pipe` file are owned by root.

$LOCKDIR/winbindd_privilaged/pipe

  The UNIX pipe over which 'privilaged' clients communicate with the winbindd program. For security reasons, access to some winbindd functions - like those needed by the ntlm_auth utility - is restricted. By default, only users in the 'root' group will get this access, however the administrator may change the group permissions on $LOCKDIR/winbindd_privilaged to allow programs like 'squid' to use ntlm_auth. Note that the winbind client will only attempt to connect to the winbindd daemon if both the `$LOCKDIR/winbindd_privilaged` directory and `$LOCKDIR/winbindd_privilaged/pipe` file are owned by root.

/lib/libnss_winbind.so.X

  Implementation of name service switch library.

$LOCKDIR/winbindd_idmap.tdb

  Storage for the Windows NT rid to UNIX user/group id mapping. The lock directory is specified when Samba is initially compiled using the `--with-lockdir` option. This directory is by default `/usr/local/samba/var/locks` .

$LOCKDIR/winbindd_cache.tdb

  Storage for cached user and group information.

## VERSION

This man page is correct for version 3.0 of the Samba suite.

## SEE ALSO

`nsswitch.conf(5)`, Samba(7), wbinfo(8), smb.conf(5)

## AUTHOR

The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.

wbinfo and winbindd were written by Tim Potter.

The conversion to DocBook for Samba 2.2 was done by Gerald Carter. The conversion to DocBook XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.