SMBPASSWD(5) UNIX System V (19 November 2002) SMBPASSWD(5)
NAME [Toc] [Back]
smbpasswd - The Samba encrypted password file
SYNOPSIS [Toc] [Back]
smbpasswd
DESCRIPTION [Toc] [Back]
This tool is part of the Samba 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 [Toc] [Back]
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
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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. In the Samba 2.2
release 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 characters.
o U - This means this is a "User" account, i.e. an
ordinary user. Only User and Workstation Trust
accounts are currently supported in the smbpasswd
file.
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)
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config file.
o D - This means the account is disabled and no
SMB/CIFS logins will be allowed for this user.
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.
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 [Toc] [Back]
This man page is correct for version 2.2 of the Samba suite.
SEE ALSO [Toc] [Back]
smbpasswd(8) samba(7) and the Internet RFC1321 for details
on the MD4 algorithm.
AUTHOR [Toc] [Back]
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/
<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 Gerald Carter
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