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man pages section 5: File Formats

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Updated: Wednesday, July 27, 2022
 
 

smbpasswd (5)

Name

smbpasswd - The Samba encrypted password file

Synopsis

smbpasswd

Description

File Formats and Conventions                                      SMBPASSWD(5)



NAME
       smbpasswd - The Samba encrypted password file

SYNOPSIS
       smbpasswd

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:

                  o   U - This means this is a "User" account, i.e. an
                      ordinary user.

                  o   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.

                  o   D - This means the account is disabled and no SMB/CIFS
                      logins will be allowed for this user.

                  o   X - This means the password does not expire.

                  o   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.

           Other flags may be added as the code is extended in future. The
           rest of this field space is filled in with spaces. For further
           information regarding the flags that are supported please refer to
           the man page for the pdbedit command.

       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 part of version 4.13.17 of the Samba suite.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE     |
       +---------------+-----------------------+
       |Availability   | service/network/samba |
       +---------------+-----------------------+
       |Stability      | Volatile              |
       +---------------+-----------------------+

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.



NOTES
       Source code for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from
       https://download.samba.org/pub/samba/stable/samba-4.13.17.tar.gz.

       Further information about this software can be found on the open source
       community website at http://www.samba.org/.



Samba 4.13.17                     06/28/2022                      SMBPASSWD(5)