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:
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.
User information traditionally stored in the passwd(5) file and used by getpwent(3) functions.
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.
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).
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.
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 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.
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 = +
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
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
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
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
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
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
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
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.
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.
The following signals can be used to manipulate the winbindd daemon.
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.
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.
Name service switch configuration file.
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.
Implementation of name service switch library.
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 .
Storage for cached user and group information.
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