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 user-
name, 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 dif-
ferent 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 dictio-
nary 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 asdisabled 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. 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 following 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
thesmb.conf(5) 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 sec-
onds 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.
SMBPASSWD(5)
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