winbindd - Name Service Switch daemon for resolving names from NT
winbindd [-D] [-F] [-S] [-i] [-Y] [-d <debug level>]
[-s <smb config file>] [-n]
This program is part of the samba(7) suite.
winbindd is a daemon that provides a number of services to the Name
Service Switch capability found in most modern C libraries, to
arbitrary applications via PAM and ntlm_auth and to Samba itself.
Even if winbind is not used for nsswitch, it still provides a service
to smbd, ntlm_auth and the pam_winbind.so PAM module, by managing
connections to domain controllers. In this configuraiton the idmap uid
and idmap gid parameters are not required. (This is known as `netlogon
proxy only mode'.)
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 through 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
The pam_winbind module supports the auth, account and password
module-types. It should be noted that the account module simply
performs a getpwnam() to verify that the system can obtain a uid for
the user, as the domain controller has already performed access
control. If the libnss_winbind library has been correctly installed, or
an alternate source of names configured, this should always succeed.
The following nsswitch databases are implemented by the winbindd
This feature is only available on IRIX. 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
passwd: files winbind
group: files winbind
## only available on IRIX: use winbind to resolve hosts:
# hosts: files dns winbind
## All other NSS enabled systems should use libnss_wins.so like this:
hosts: files dns wins
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.
hosts: files wins
If specified, this parameter causes the server to operate as a
daemon. That is, it detaches itself and runs in the background on
the appropriate port. This switch is assumed if winbindd is
executed on the command line of a shell.
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.
If specified, this parameter causes winbindd to log to standard
output rather than a file.
level is an integer from 0 to 10. The default value if this
parameter is not specified is 0.
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
smb.conf.html# parameter in the smb.conf file.
Prints the program version number.
-s|--configfile <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.
Base directory name for log/debug files. The extension ".progname"
will be appended (e.g. log.smbclient, log.smbd, etc...). The log
file is never removed by the client.
Print a summary of command line options.
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.
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
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 security id
(SID) which is globally unique when the user or group is created. To
convert the Windows NT user or group into a unix user or group, a
mapping between SIDs and unix user and group ids is required. This is
one of the jobs that
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 and will be
WARNING: The SID to unix id database is the only location where the
user and group mappings are stored by winbindd. If this store 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.
o winbind separator
o idmap uid
o idmap gid
o idmap backend
o winbind cache time
o winbind enum users
o winbind enum groups
o template homedir
o template shell
o winbind use default domain
o winbind: rpc only Setting this parameter forces winbindd to use
RPC instead of LDAP to retrieve information from Domain
To setup winbindd for user and group lookups plus authentication from a
domain controller use something like the following setup. This was
tested on an early Red Hat 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_unix.so \
use_first_pass shadow nullok
The PAM module pam_unix has recently replaced the module pam_pwdb.
Some Linux systems use the module pam_unix2 in place of pam_unix.
Note in particular the use of the sufficient keyword and the
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
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
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
Finally, setup a smb.conf(5) containing directives like the following:
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.
The following notes are useful when configuring and running winbindd:
nmbd(8) must be running on the local machine for winbindd to work.
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, unless a
shared idmap backend is configured.
If the the Windows NT SID 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 SIGUSR2 signal will cause
winbindd to write status information to the winbind log file.
Log files are stored in the filename specified by the log file
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.
The UNIX pipe over which 'privileged' 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 /var/run/samba/winbindd_privileged 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
/var/run/samba/winbindd_privileged directory and
/var/run/samba/winbindd_privileged/pipe file are owned by root.
Implementation of name service switch library.
Storage for the Windows NT rid to UNIX user/group id mapping.
Storage for cached user and group information.
This man page is correct for version 3 of the Samba suite.
nsswitch.conf(5), samba(7), wbinfo(1), ntlm_auth(8), smb.conf(5),
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