winbindd
8

# winbindd

Name Service Switch daemon for resolving names from NT servers

    		winbindd
    		-i
    		-d <debug level>
    		-s <smb config file>

## DESCRIPTION

This program is part of the Samba 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 is 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 suceed.

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

-d debuglevel

  Sets the debuglevel to an integer between 0 and 100. 0 is for no debugging and 100 is for reams and reams. To submit a bug report to the Samba Team, use debug level 100 (see BUGS.txt).

-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.

## 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

  The winbind separator option allows you to specify how NT domain names and user names are combined into unix user names when presented to users. By default, `winbindd` will use the traditional '\' separator so that the unix user names look like DOMAIN\username. In some cases this separator character may cause problems as the '\' character has special meaning in unix shells. In that case you can use the winbind separator option to specify an alternative separator character. Good alternatives may be '/' (although that conflicts with the unix directory separator) or a '+ 'character. The '+' character appears to be the best choice for 100% compatibility with existing unix utilities, but may be an aesthetically bad choice depending on your taste.

  Default: `winbind separator = \`

  Example: `winbind separator = +`

winbind uid

  The winbind uid parameter specifies the range of user ids that are allocated by the winbindd daemon. This range of ids should have no existing local or NIS users within it as strange conflicts can occur otherwise.

  Default: `winbind uid = <empty string>`

  Example: `winbind uid = 10000-20000`

winbind gid

  The winbind gid parameter specifies the range of group ids that are allocated by the winbindd daemon. This range of group ids should have no existing local or NIS groups within it as strange conflicts can occur otherwise.

  Default: `winbind gid = <empty string>`

  Example: `winbind gid = 10000-20000`

winbind cache time

  This parameter specifies the number of seconds the winbindd daemon will cache user and group information before querying a Windows NT server again. When a item in the cache is older than this time winbindd will ask the domain controller for the sequence number of the server's account database. If the sequence number has not changed then the cached item is marked as valid for a further `winbind cache time` seconds. Otherwise the item is fetched from the server. This means that as long as the account database is not actively changing winbindd will only have to send one sequence number query packet every `winbind cache time` seconds.

  Default: `winbind cache time = 15`

winbind enum users

  On large installations it may be necessary to suppress the enumeration of users through the `setpwent()`, `getpwent()` and `endpwent()` group of system calls. If the `winbind enum users` parameter is false, calls to the `getpwent` system call will not return any data.

  Warning: Turning off user enumeration may cause some programs to behave oddly. For example, the `finger` program relies on having access to the full user list when searching for matching usernames.

  Default: `winbind enum users = yes`

winbind enum groups

  On large installations it may be necessary to suppress the enumeration of groups through the `setgrent()`, `getgrent()` and `endgrent()` group of system calls. If the `winbind enum groups` parameter is false, calls to the `getgrent()` system call will not return any data.

  Warning: Turning off group enumeration may cause some programs to behave oddly.

  Default: `winbind enum groups = no`

template homedir

  When filling out the user information for a Windows NT user, the `winbindd` daemon uses this parameter to fill in the home directory for that user. If the string `%D` is present it is substituted with the user's Windows NT domain name. If the string `%U` is present it is substituted with the user's Windows NT user name.

  Default: `template homedir = /home/%D/%U`

template shell

  When filling out the user information for a Windows NT user, the `winbindd` daemon uses this parameter to fill in the shell for that user.

  Default: `template shell = /bin/false`

## 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 `smbpasswd` program like this:

`smbpasswd -j DOMAIN -r PDC -U Administrator`

The username after the `-U` can be any Domain user that has administrator privileges on the machine. Substitute your domain name for "DOMAIN" and the name 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` containing directives like the following:

    [global]
    	winbind separator = +
            winbind cache time = 10
            template shell = /bin/bash
            template homedir = /home/%D/%U
            winbind uid = 10000-20000
            winbind 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` 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.

Client processes resolving names through the `winbindd` nsswitch module read an environment variable named `$WINBINDD_DOMAIN`. If this variable contains a comma separated list of Windows NT domain names, then winbindd will only resolve users and groups within those Windows NT domains.

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.

SIGUSR1

  The SIGUSR1 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.

/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 2.2 of the Samba suite.

## SEE ALSO

`nsswitch.conf(5)`, samba(7), wbinfo(1), 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