smbpasswd - change a user's SMB password
When run by root:
smbpasswd [ options ] [ username ] [ password ]
smbpasswd [ options ] [ password ]
This tool is part of the Samba suite.
The smbpasswd program has several different functions, depending on whether it is run by
the root user or not. When run as a normal user it allows the user to change the password
used for their SMB sessions on any machines that store SMB passwords.
By default (when run with no arguments) it will attempt to change the current user's SMB
password on the local machine. This is similar to the way the passwd(1) program works.
smbpasswd differs from how the passwd program works however in that it is not setuid root
but works in a client-server mode and communicates with a locally running smbd(8). As a
consequence in order for this to succeed the smbd daemon must be running on the local
machine. On a UNIX machine the encrypted SMB passwords are usually stored in the smb-
When run by an ordinary user with no options. smbpasswd will prompt them for their old SMB
password and then ask them for their new password twice, to ensure that the new password
was typed correctly. No passwords will be echoed on the screen whilst being typed. If you
have a blank SMB password (specified by the string "NO PASSWORD" in the smbpasswd file)
then just press the <Enter> key when asked for your old password.
smbpasswd can also be used by a normal user to change their SMB password on remote
machines, such as Windows NT Primary Domain Controllers. See the (-r) and -U options
When run by root, smbpasswd allows new users to be added and deleted in the smbpasswd
file, as well as allows changes to the attributes of the user in this file to be made.
When run by root, smbpasswd accesses the local smbpasswd file directly, thus enabling
changes to be made even if smbd is not running.
-L Run the smbpasswd command in local mode. This allows a non-root user to specify the
root-only options. This is used mostly in test environments where a non-root user
needs to make changes to the local smbpasswd file. The smbpasswd file must have
read/write permissions for the user running the command.
-h This option prints the help string for smbpasswd.
-c smb.conf file
This option specifies that the configuration file specified should be used instead
of the default value specified at compile time.
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 smbpasswd. At level 0, only critical errors and serious warnings will
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 cryp-
-r remote machine name
This option allows a user to specify what machine they wish to change their pass-
word on. Without this parameter smbpasswd defaults to the local host. The remote
machine name is the NetBIOS name of the SMB/CIFS server to contact to attempt the
password change. This name is resolved into an IP address using the standard name
resolution mechanism in all programs of the Samba suite. See the -R name resolve
order parameter for details on changing this resolving mechanism.
The username whose password is changed is that of the current UNIX logged on user.
See the -U username parameter for details on changing the password for a different
Note that if changing a Windows NT Domain password the remote machine specified
must be the Primary Domain Controller for the domain (Backup Domain Controllers
only have a read-only copy of the user account database and will not allow the
Note that Windows 95/98 do not have a real password database so it is not possible
to change passwords specifying a Win95/98 machine as remote machine target.
-s This option causes smbpasswd to be silent (i.e. not issue prompts) and to read its
old and new passwords from standard input, rather than from /dev/tty (like the
passwd(1) program does). This option is to aid people writing scripts to drive smb-
-S This option causes smbpasswd to query a domain controller of the domain specified
by the workgroup parameter in smb.conf and store the domain SID in the secrets.tdb
file as its own machine SID. This is only useful when configuring a Samba PDC and
Samba BDC, or when migrating from a Windows PDC to a Samba PDC.
The -r options can be used as well to indicate a specific domain controller which
should be contacted. In this case, the domain SID obtained is the one for the
domain to which the remote machine belongs.
-t This option is used to force smbpasswd to change the current password assigned to
the machine trust account when operating in domain security mode. This is really
meant to be used on systems that only run winbindd Under server installations, smbd
handle the password updates automatically.
This option may only be used in conjunction with the -r option. When changing a
password on a remote machine it allows the user to specify the user name on that
machine whose password will be changed. It is present to allow users who have dif-
ferent user names on different systems to change these passwords. The optional
%pass may be used to specify to old password.
In particular, this parameter specifies the username used to create the machine
account when invoked with -j
NOTE: The following options are available only when the smbpasswd command is run as root
or in local mode.
-a This option specifies that the username following should be added to the local smb-
passwd file, with the new password typed. This option is ignored if the username
specified already exists in the smbpasswd file and it is treated like a regular
change password command. Note that the user to be added must already exist in the
system password file (usually /etc/passwd) else the request to add the user will
-d This option specifies that the username following should be disabled in the local
smbpasswd file. This is done by writing a 'D' flag into the account control space
in the smbpasswd file. Once this is done all attempts to authenticate via SMB using
this username will fail.
If the smbpasswd file is in the 'old' format (pre-Samba 2.0 format) there is no
space in the user's password entry to write this information and so the user is
disabled by writing 'X' characters into the password space in the smbpasswd file.
See smbpasswd(5) for details on the 'old' and new password file formats.
-e This option specifies that the username following should be enabled in the local
smbpasswd file, if the account was previously disabled. If the account was not dis-
abled this option has no effect. Once the account is enabled then the user will be
able to authenticate via SMB once again.
If the smbpasswd file is in the 'old' format, then smbpasswd will prompt for a new
password for this user, otherwise the account will be enabled by removing the 'D'
flag from account control space in the smbpasswd file. See smbpasswd (5) for
details on the 'old' and new password file formats.
-m This option tells smbpasswd that the account being changed is a MACHINE account.
Currently this is used when Samba is being used as an NT Primary Domain Controller.
-n This option specifies that the username following should have their password set to
null (i.e. a blank password) in the local smbpasswd file. This is done by writing
the string "NO PASSWORD" as the first part of the first password stored in the smb-
Note that to allow users to logon to a Samba server once the password has been set
to "NO PASSWORD" in the smbpasswd file the administrator must set the following
parameter in the [global] section of the smb.conf file :
null passwords = yes
This parameter is only available is Samba has been configured to use the experimen-
tal --with-ldapsam option. The -w switch is used to specify the password to be used
with the ldap admin dn Note that the password is stored in the private/secrets.tdb
and is keyed off of the admin's DN. This means that if the value of ldap admin dn
ever changes, the password will need to be manually updated as well.
-x This option specifies that the username following should be deleted from the local
This option is used to add a Samba server into a Windows NT Domain, as a Domain
member capable of authenticating user accounts to any Domain Controller in the same
way as a Windows NT Server. See the security = domain option in the smb.conf(5) man
This command can work both with and without the -U parameter.
When invoked with -U, that username (and optional password) are used to contact the
PDC (which must be specified with -r) to both create a machine account, and to set
a password on it.
Alternately, if -U is omitted, Samba will contact its PDC and attempt to change the
password on a pre-existing account.
In order to be used in this way, the Administrator for the Windows NT Domain must
have used the program "Server Manager for Domains" to add the primary NetBIOS name
of the Samba server as a member of the Domain.
After this has been done, to join the Domain invoke smbpasswd with this parameter.
smbpasswd will then look up the Primary Domain Controller for the Domain (found in
the smb.conf file in the parameter password server and change the machine account
password used to create the secure Domain communication.
Either way, this password is then stored by smbpasswd in a TDB, writeable only by
root, called secrets.tdb
Once this operation has been performed the smb.conf file may be updated to set the
security = domain option and all future logins to the Samba server will be authen-
ticated to the Windows NT PDC.
Note that even though the authentication is being done to the PDC all users access-
ing the Samba server must still have a valid UNIX account on that machine. The
winbindd(8) daemon can be used to create UNIX accounts for NT users.
-R name resolve order
This option allows the user of smbpasswd to determine what name resolution services
to use when looking up the NetBIOS name of the host being connected to.
The options are :"lmhosts", "host", "wins" and "bcast". They cause names to be
resolved as follows :
o lmhosts : Lookup an IP address in the Samba lmhosts file. If the line in lmhosts
has no name type attached to the NetBIOS name (see the lmhosts(5) for details)
then any name type matches for lookup.
o host : Do a standard host name to IP address resolution, using the system
/etc/hosts , NIS, or DNS lookups. This method of name resolution is operating
system dependent. For instance, on IRIX or Solaris this may be controlled by the
/etc/nsswitch.conf file). Note that this method is only used if the NetBIOS name
type being queried is the 0x20 (server) name type, otherwise it is ignored.
o wins : Query a name with the IP address listed in the wins server parameter. If
no WINS server has been specified this method will be ignored.
o bcast : Do a broadcast on each of the known local interfaces listed in the inter-
faces parameter. This is the least reliable of the name resolution methods as it
depends on the target host being on a locally connected subnet.
The default order is lmhosts, host, wins, bcast and without this parameter or any entry in
the smb.conf file the name resolution methods will be attempted in this order.
This specifies the username for all of the root only options to operate on. Only
root can specify this parameter as only root has the permission needed to modify
attributes directly in the local smbpasswd file.
This specifies the new password. If this parameter is specified you will not be
prompted for the new password.
Since smbpasswd works in client-server mode communicating with a local smbd for a non-root
user then the smbd daemon must be running for this to work. A common problem is to add a
restriction to the hosts that may access the smbd running on the local machine by speci-
fying a allow hosts or deny hosts entry in the smb.conf file and neglecting to allow
"localhost" access to the smbd.
In addition, the smbpasswd command is only useful if Samba has been set up to use
encrypted passwords. See the file ENCRYPTION.txt in the docs directory for details on how
to do this.
This man page is correct for version 2.2 of the Samba suite.
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.
The original Samba man pages were written by Karl Auer. The man page sources were con-
verted to YODL format (another excellent piece of Open Source software, available at
ftp://ftp.icce.rug.nl/pub/unix/ <URL:ftp://ftp.icce.rug.nl/pub/unix/>) and updated for the
Samba 2.0 release by Jeremy Allison. The conversion to DocBook for Samba 2.2 was done by
19 November 2002 SMBPASSWD(8)