smbpasswd(5)
SMBPASSWD(5) FILE FORMATS 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 ithin
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
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SMBPASSWD(5) FILE FORMATS SMBPASSWD(5)
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 algo-
rithm. 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 ordi-
nary user.
•
N - This means the account has no password (the pass-
words in the fields LANMAN Password Hash and NT Pass-
word 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)
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SMBPASSWD(5) FILE FORMATS SMBPASSWD(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.
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 correct for version 3.0 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 Doc-
Book XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.
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