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SMBPASSWD
Section: File Formats and Conventions (5)Updated: 01/25/2022
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NAME
smbpasswd - The Samba encrypted password fileSYNOPSIS
DESCRIPTION
This tool is part of the samba(7) suite.
smbpasswd is the Samba encrypted password file. It contains the username, Unix user id and the SMB hashed passwords of the user, as well as account flag information and the time the password was last changed. This file format has been evolving with Samba and has had several different formats in the past.
FILE FORMAT
The format of the smbpasswd file used by Samba 2.2 is very similar to the familiar Unix passwd(5) file. It is an ASCII file containing one line for each user. Each field within each line is separated from the next by a colon. Any entry beginning with '#' is ignored. The smbpasswd file contains the following information for each user:
name
- This is the user name. It must be a name that already exists in the standard UNIX passwd file.
uid
- This is the UNIX uid. It must match the uid field for the same user entry in the standard UNIX passwd file. If this does not match then Samba will refuse to recognize this smbpasswd file entry as being valid for a user.
Lanman Password Hash
-
This is the LANMAN hash of the user's password, encoded as 32 hex digits. The LANMAN hash is created by DES encrypting a well known string with the user's password as the DES key. This is the same password used by Windows 95/98 machines. Note that this password hash is regarded as weak as it is vulnerable to dictionary attacks and if two users choose the same password this entry will be identical (i.e. the password is not "salted" as the UNIX password is). If the user has a null password this field will contain the characters "NO PASSWORD" as the start of the hex string. If the hex string is equal to 32 'X' characters then the user's account is marked as
disabled
and the user will not be able to log onto the Samba server.
WARNING !! Note that, due to the challenge-response nature of the SMB/CIFS authentication protocol, anyone with a knowledge of this password hash will be able to impersonate the user on the network. For this reason these hashes are known as plain text equivalents and must NOT be made available to anyone but the root user. To protect these passwords the smbpasswd file is placed in a directory with read and traverse access only to the root user and the smbpasswd file itself must be set to be read/write only by root, with no other access.
NT Password Hash
-
This is the Windows NT hash of the user's password, encoded as 32 hex digits. The Windows NT hash is created by taking the user's password as represented in 16-bit, little-endian UNICODE and then applying the MD4 (internet rfc1321) hashing algorithm to it.
This password hash is considered more secure than the LANMAN Password Hash as it preserves the case of the password and uses a much higher quality hashing algorithm. However, it is still the case that if two users choose the same password this entry will be identical (i.e. the password is not "salted" as the UNIX password is).
WARNING !!. Note that, due to the challenge-response nature of the SMB/CIFS authentication protocol, anyone with a knowledge of this password hash will be able to impersonate the user on the network. For this reason these hashes are known as plain text equivalents and must NOT be made available to anyone but the root user. To protect these passwords the smbpasswd file is placed in a directory with read and traverse access only to the root user and the smbpasswd file itself must be set to be read/write only by root, with no other access.
Account Flags
-
This section contains flags that describe the attributes of the users account. This field is bracketed by '[' and ']' characters and is always 13 characters in length (including the '[' and ']' characters). The contents of this field may be any of the following characters:
-
- • U - This means this is a "User" account, i.e. an ordinary user.
- • N - This means the account has no password (the passwords in the fields LANMAN Password Hash and NT Password Hash are ignored). Note that this will only allow users to log on with no password if the null passwords parameter is set in the smb.conf(5) config file.
- • D - This means the account is disabled and no SMB/CIFS logins will be allowed for this user.
- • X - This means the password does not expire.
- • W - This means this account is a "Workstation Trust" account. This kind of account is used in the Samba PDC code stream to allow Windows NT Workstations and Servers to join a Domain hosted by a Samba PDC.
-
Last Change Time
- This field consists of the time the account was last modified. It consists of the characters 'LCT-' (standing for "Last Change Time") followed by a numeric encoding of the UNIX time in seconds since the epoch (1970) that the last change was made.
All other colon separated fields are ignored at this time.
VERSION
This man page is correct for version 3 of the Samba suite.
SEE ALSO
smbpasswd(8), Samba(7), and the Internet RFC1321 for details on the MD4 algorithm.
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.
The original Samba man pages were written by Karl Auer. The man page sources were converted to YODL format (another excellent piece of Open Source software, available at 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 Gerald Carter. The conversion to DocBook XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.
Index
This document was created by man2html, using the manual pages.
Time: 04:45:56 GMT, September 16, 2022 Content-type: text/html; charset=UTF-8
SMBPASSWD
Section: System Administration tools (8)Updated: 01/25/2022
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NAME
smbpasswd - change a user's SMB passwordSYNOPSIS
- smbpasswd [-a] [-c <config file>] [-x] [-d] [-e] [-D debuglevel] [-n] [-r <remote machine>] [-R <name resolve order>] [-m] [-U username[%password]] [-h] [-s] [-w pass] [-W] [-i] [-L] [username]
DESCRIPTION
This tool is part of the samba(7) 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 smbpasswd(5) file.
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 below.
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.
OPTIONS
-a
-
This option specifies that the username following should be added to the local smbpasswd file, with the new password typed (type <Enter> for the old password). This option is ignored if the username following already exists in the smbpasswd file and it is treated like a regular change password command. Note that the default passdb backends require the user to already exist in the system password file (usually
/etc/passwd), else the request to add the user will fail.
This option is only available when running smbpasswd as root.
-c
- This option can be used to specify the path and file name of the smb.conf configuration file when it is important to use other than the default file and / or location.
-x
-
This option specifies that the username following should be deleted from the local smbpasswd file.
This option is only available when running smbpasswd as root.
-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 the command will FAIL. See smbpasswd(5) for details on the 'old' and new password file formats.
This option is only available when running smbpasswd as root.
-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 disabled 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 FAIL to enable the account. See smbpasswd(5) for details on the 'old' and new password file formats.
This option is only available when running smbpasswd as root.
-D 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 smbpasswd. At level 0, only critical errors and serious warnings will be logged.
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.
-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 smbpasswd file.
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 option is only available when running smbpasswd as root.
-r remote machine name
-
This option allows a user to specify what machine they wish to change their password 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 username.
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 password change).
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.
-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:
-
- • 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.
- • 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 depended 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.
- • 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.
- • bcast: Do a broadcast on each of the known local interfaces listed in the interfaces parameter. This is the least reliable of the name resolution methods as it depends on the target host being on a locally connected subnet.
-
-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.
This option is only available when running smbpasswd as root.
-U username
- 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 different user names on different systems to change these passwords.
-h
- This option prints the help string for smbpasswd, selecting the correct one for running as root or as an ordinary user.
-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 smbpasswd
-w password
- This parameter is only available if Samba has been compiled with LDAP support. The -w switch is used to specify the password to be used with the m[blue]ldap admin dnm[]. Note that the password is stored in the 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.
-W
-
NOTE:
This option is same as "-w" except that the password should be entered using stdin.
This parameter is only available if Samba has been compiled with LDAP support. The -W switch is used to specify the password to be used with the m[blue]ldap admin dnm[]. Note that the password is stored in the 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.
-i
-
This option tells smbpasswd that the account being changed is an interdomain trust account. Currently this is used when Samba is being used as an NT Primary Domain Controller. The account contains the info about another trusted domain.
This option is only available when running smbpasswd as root.
-L
- Run in local mode.
username
- 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.
NOTES
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 specifying either allow hosts or deny hosts entry in the smb.conf(5) 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.
VERSION
This man page is correct for version 3 of the Samba suite.
SEE ALSO
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.
The original Samba man pages were written by Karl Auer. The man page sources were converted to YODL format (another excellent piece of Open Source software, available at 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 Gerald Carter. The conversion to DocBook XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.
Index
This document was created by man2html, using the manual pages.
Time: 04:45:59 GMT, September 16, 2022
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